Arena arrived at her present location on 3 June, 21 days ago. She was the first of our radio-tagged peregrines to head north from Chile and apparently the first to arrive on her breeding range in Canada.
During the last three weeks, her signals show that she wandered about the area for awhile but has generally favored the site where she arrived first. The latest cluster of signals (one per day over the last 10 days) indicate the most probable location of her nest site. It is necessary to zoom in to separate the location dots on Google Earth. There is a wide spread around the central point, possibly due to her continued flights about the area. Most are within a short distance of the central area.
While we all like to think that she is successfully breeding there, I have to stress that we can't know for certain without an actual visit to the site.
Showing posts with label "Arena". Show all posts
Showing posts with label "Arena". Show all posts
June 24, 2007
June 14, 2007
Important Notice:Duty Cycles Winding Down
There will be a major change tomorrow involving the satellite transmitter duty cycles. We are going to be transitioning from the current daily signals to a previously-programmed interval of one signal every ten days. This change will only impact the five female peregrines, i.e. Linda and Arena in North America and La Serena, Coquimba and Houdini in Chile.
The signals from the two males will remain the same, i.e. one signal every 52 hours.
This new program will generate locations for the female falcons only one time every 10 days until the fall season, when they will switch back on for the autumn migration.
For those considering putting satellite transmitters on peregrines in the future, it is important to know that we had deliberately programmed our transmitters in this manner. Based on the literature and interviews with other peregrine people working in the far north, we had anticipated that all of the migrant birds would be on territory by now. And perhaps they are. We felt that once we learned the location of the nest sites, additional signals from the area would be redundant.
In addition, we were overly conservative in setting the falcon departure dates from Chile. We thought migrant peregrines would be heading north by mid-March, when in reality, they all departed in April.
Finally, as the migration period begins to wind down, we would encourage our readers to stay tuned to this site next fall when we plan to follow the birds south via satellite.
In fact, I would encourage all of you to check in with this site periodically as we may have some interesting suprises in store for the future.
The signals from the two males will remain the same, i.e. one signal every 52 hours.
This new program will generate locations for the female falcons only one time every 10 days until the fall season, when they will switch back on for the autumn migration.
For those considering putting satellite transmitters on peregrines in the future, it is important to know that we had deliberately programmed our transmitters in this manner. Based on the literature and interviews with other peregrine people working in the far north, we had anticipated that all of the migrant birds would be on territory by now. And perhaps they are. We felt that once we learned the location of the nest sites, additional signals from the area would be redundant.
In addition, we were overly conservative in setting the falcon departure dates from Chile. We thought migrant peregrines would be heading north by mid-March, when in reality, they all departed in April.
Finally, as the migration period begins to wind down, we would encourage our readers to stay tuned to this site next fall when we plan to follow the birds south via satellite.
In fact, I would encourage all of you to check in with this site periodically as we may have some interesting suprises in store for the future.
Arena Still at Ungava
Arena arrived at her present location on 3 June and has remained in the area over the last 9 days (12 June). This is strong evidence that she has arrived at her nesting area. She is moving back and forth between two places separated by about 16 km (10 miles).
We'll continue to monitor her movements and expect that if she puts down eggs, her signal will become stationary at a cliff site.
We'll continue to monitor her movements and expect that if she puts down eggs, her signal will become stationary at a cliff site.
June 8, 2007
Arena Remaining in Ungava
As most of you have noticed, Arena has spent the last 6 days in the same general area on the Ungava Peninsula. We strongly suspect that she is at or near her nest site but we need more data to be certain.
Since this is the first time that we have done this, we are debating how to determine if she is truly "home". Our best approach is to give her more time and see if she remains there. We are all acutely aware that she could easily move on at any moment and follow Sparrow King on to Baffin Island. So we are waiting to see what happens next. We expect all of you are doing the same thing.
On another subject, the duty cycle for the two female transmitters will change radically on 15 June, a week from today. We had expected the females to be on territory by mid-June, based on all of the Arctic breeding data that we examined from Alaska, Greenland and Canada. However, our best estimates appear to be too early for Linda. She may still be migrating at that time.
However, we will still get signals every ten days throughout the summer, so even if she is still moving, we should be able to pinpoint her breeding territory.
The male transmitters will stay the same.
Since this is the first time that we have done this, we are debating how to determine if she is truly "home". Our best approach is to give her more time and see if she remains there. We are all acutely aware that she could easily move on at any moment and follow Sparrow King on to Baffin Island. So we are waiting to see what happens next. We expect all of you are doing the same thing.
On another subject, the duty cycle for the two female transmitters will change radically on 15 June, a week from today. We had expected the females to be on territory by mid-June, based on all of the Arctic breeding data that we examined from Alaska, Greenland and Canada. However, our best estimates appear to be too early for Linda. She may still be migrating at that time.
However, we will still get signals every ten days throughout the summer, so even if she is still moving, we should be able to pinpoint her breeding territory.
The male transmitters will stay the same.
June 5, 2007
Is Arena At Her Eyrie?
Arena left the Belcher Islands and headed northeast across the base of the Ungava Peninsula and on a line towards Baffin Island. There was rampant speculation that this route might even take her to Greenland, However, for the last three days, she has paused in a beautiful area of lakes and streams, well inland from the coast.
So we are now confronted with the question of how to tell if she is at her nest or eyrie. She could just as well be taking a break and feeding up. The only way to tell is to just wait and see. Alastair Franke, one of the Canadian peregrine biologists working in this area, tells us that eggs are due at this latitude about now. So maybe she is home, maybe not.
So we are now confronted with the question of how to tell if she is at her nest or eyrie. She could just as well be taking a break and feeding up. The only way to tell is to just wait and see. Alastair Franke, one of the Canadian peregrine biologists working in this area, tells us that eggs are due at this latitude about now. So maybe she is home, maybe not.
June 1, 2007
Arena and the Belcher Islands
I had a closer look at the data from Arena this morning and discovered that she had likely roosted on the ice on two different nights. On the night of 30 May, the GPS signal indicates that she roosted offshore about 510 meters (557 yards) SW of a small island in the southern Belcher Group. I think that it is a good assumption she was sleeping on the ice as I can't really think of what else would be there.
The following night at 1 AM, she was near another small island and yet she apparently slept on the ice once more, this time about 886 meters (969 yards) offshore.
Why she would prefer to sleep on the ice and not on the islands is unknown to me. Are there predators in the area? What could kill a migrant peregrine in Hudson Bay?
I'll have to ask our arctic colleagues whether there are records of migrant peregrines sleeping on ice floes.
We do know that there is still alot of ice in Hudson Bay at this time. I'm told that, in general, it begins to melt in May and should be mostly ice-free by August.
You can see what these very unusual islands look like at http://www.oceandots.com/arctic/canada/belcher.htm.They have no trees, little surface soil and are classified as tundra. The wildlife includes walrus, Snowy Owls, Beluga whales and Polar Bears.
Arena is definitely a long way from the Atacama Desert in Chile
The following night at 1 AM, she was near another small island and yet she apparently slept on the ice once more, this time about 886 meters (969 yards) offshore.
Why she would prefer to sleep on the ice and not on the islands is unknown to me. Are there predators in the area? What could kill a migrant peregrine in Hudson Bay?
I'll have to ask our arctic colleagues whether there are records of migrant peregrines sleeping on ice floes.
We do know that there is still alot of ice in Hudson Bay at this time. I'm told that, in general, it begins to melt in May and should be mostly ice-free by August.
You can see what these very unusual islands look like at http://www.oceandots.com/arctic/canada/belcher.htm.They have no trees, little surface soil and are classified as tundra. The wildlife includes walrus, Snowy Owls, Beluga whales and Polar Bears.
Arena is definitely a long way from the Atacama Desert in Chile
May 30, 2007
Arena Moving through Hudson Bay
Arena re-commenced her northward movement out of Minnesota crossing into Canada (her 11th country) just SE of Winnipeg, Manitoba, on 23 May. As Don McCall writes "she blasted past the border" flying 244 miles on Wednesday and committing to a strong move towards home. That night, she roosted in the adjacent province, Ontario.
She continued north and roosted again in Ontario the next night.
On 25 May, she flew right along the Ontario/Manitoba, paralleling it almost exactly, and the following day, she arrived at the shores of Hudson's Bay.
Our Canadian colleague, Alastair Franke, had just left for the famous peregrine study area of Rankin Inlet in the Hudson Bay area with Gordon Court. They have produced some of the finest peregrine breeding data in existence and were excited about the tagged falcons passing through their area. We are all hoping that one of the satellite birds will nest near their study area.
On 28 May, the satellite data showed that Arena was perched 65 km (40 miles) offshore in Hudson Bay. We could see no islands at this point on Google Earth and wondered what she was doing there. We then realized that she was perching on ice! At this time of year, the waters there still have winter ice.
The following day, Arena did a remarkable jump, flying 426 km (265 miles) in 8 hours, nearly reaching the NE shore of the Bay.
I queried Alastair about the situation up there at present and he kindly wrote..
"She's likely sitting on the floe edge hunting guillemot, longtail duck or anything else that tickles her fancy - the Hudson Bay still has land fast ice at this time of year. We've been sitting here in Rankin talking about your site and the data that are daily available - it is awesome! Very surprising that Seven is still in southern Mexico, Linda in northern Mexico and Sparrow King not yet in Canada. These birds are really cutting it fine if they are going to breed...in Rankin, initiation of egg laying is June 8 - only a week away now. Most sites are occupied with pairs, we're seeing lots of copulation and territorial defence. I can't wait to see what your birds do."
Thanks for your comments Alastair. As always, there is nothing like having a report from an expert in the field where this is all happening.
Since her jump, Arena has curved to the south along the eastern shore of Hudson Bay.
Don McCall writes...
"Arena had nearly crossed Hudson Bay by mid-morning. As Bud pointed out to me, she doesn't need any islands to perch offshore since Hudson Bay is now covered with ice. I had no idea that was true of southern Hudson Bay in May (I've been in Seattle too long). Unless she changes course (which she has done frequently) she appears headed for the southern tip of Baffin Island or perhaps Greenland. Of course, nobody has predicted anything correctly about her yet so that's probably wrong."
What Don states it true. Most of what we (and me especially) have predicted for this bird has been wrong. However, without meaning to put a spin on this, I would say that therein lies the complete value of satellite tagging. The new technology allows us to identify our prejudices and our expectations. It forces us to confront how little we really know about what happens to peregrines on migration. And it corrects our thinking as it happens. This is how science moves forward.
She continued north and roosted again in Ontario the next night.
On 25 May, she flew right along the Ontario/Manitoba, paralleling it almost exactly, and the following day, she arrived at the shores of Hudson's Bay.
Our Canadian colleague, Alastair Franke, had just left for the famous peregrine study area of Rankin Inlet in the Hudson Bay area with Gordon Court. They have produced some of the finest peregrine breeding data in existence and were excited about the tagged falcons passing through their area. We are all hoping that one of the satellite birds will nest near their study area.
On 28 May, the satellite data showed that Arena was perched 65 km (40 miles) offshore in Hudson Bay. We could see no islands at this point on Google Earth and wondered what she was doing there. We then realized that she was perching on ice! At this time of year, the waters there still have winter ice.
The following day, Arena did a remarkable jump, flying 426 km (265 miles) in 8 hours, nearly reaching the NE shore of the Bay.
I queried Alastair about the situation up there at present and he kindly wrote..
"She's likely sitting on the floe edge hunting guillemot, longtail duck or anything else that tickles her fancy - the Hudson Bay still has land fast ice at this time of year. We've been sitting here in Rankin talking about your site and the data that are daily available - it is awesome! Very surprising that Seven is still in southern Mexico, Linda in northern Mexico and Sparrow King not yet in Canada. These birds are really cutting it fine if they are going to breed...in Rankin, initiation of egg laying is June 8 - only a week away now. Most sites are occupied with pairs, we're seeing lots of copulation and territorial defence. I can't wait to see what your birds do."
Thanks for your comments Alastair. As always, there is nothing like having a report from an expert in the field where this is all happening.
Since her jump, Arena has curved to the south along the eastern shore of Hudson Bay.
Don McCall writes...
"Arena had nearly crossed Hudson Bay by mid-morning. As Bud pointed out to me, she doesn't need any islands to perch offshore since Hudson Bay is now covered with ice. I had no idea that was true of southern Hudson Bay in May (I've been in Seattle too long). Unless she changes course (which she has done frequently) she appears headed for the southern tip of Baffin Island or perhaps Greenland. Of course, nobody has predicted anything correctly about her yet so that's probably wrong."
What Don states it true. Most of what we (and me especially) have predicted for this bird has been wrong. However, without meaning to put a spin on this, I would say that therein lies the complete value of satellite tagging. The new technology allows us to identify our prejudices and our expectations. It forces us to confront how little we really know about what happens to peregrines on migration. And it corrects our thinking as it happens. This is how science moves forward.
May 20, 2007
Arena Pauses at the Canadian Border
Arena moved north over the central plains of the US last week. She passed through Nebraska, South Dakota, North Dakota and into the northwest tip of Minnesota by 17 May. However, for some reason, she held up just south of the Canadian border. Despite unruly comments from some of our readers, it did not involve an expired passport or more stringent immigration policies in Canada.
She spent two nights in Minnesota before inexplicably flying south 150 km into North Dakota. We have no idea why.
We also noticed that she has veered substantially from what we expected to be an overall NW vector. She just sort of curved over to the NNE.
Arena continues to confound us all with her wonderful behavior, seldom doing what we predict so confidently.
She spent two nights in Minnesota before inexplicably flying south 150 km into North Dakota. We have no idea why.
We also noticed that she has veered substantially from what we expected to be an overall NW vector. She just sort of curved over to the NNE.
Arena continues to confound us all with her wonderful behavior, seldom doing what we predict so confidently.
May 15, 2007
Arena Sets Another New Record Crossing the US
On 10 May, Arena arrived in the United States. On her first night in Texas , she roosted in an oilfield. The following day, (11 May) she continued north and covered another 357 km (222 miles). It is clear that she is "racing" for home at this time. She appears to have roosted that night in a tree in hill country about 7 km (5 miles) from Kimble, Texas. The next day (12 May), she continued to migrate north through Texas and flew a distance of 402 km (250 miles), increasing her distances substantially. She was flying over some extensive agricultural areas as can be seen on Google Earth. The patchwork quilting formed by the various fields and agriculture "circles" are stunning to examine by satellite photos. That night she put down in fields NE of Lubbock, Texas and more precisely, 8 km (5 miles) SE of the small town of Petersburg, Texas. Her roost site looks quite interesting. From the satellite image, it would appear that she might have slept on the ground. The image shows a furrowed field apparently devoid of perches. No trees are visible within the normal 20 meter range of accuracy. Since these satellite images are not real time, there could easily be something that we cannot see. But the possibility of a ground roost is still intriguing.
The following day (13 May), Arena set a new distance record for the season. She flew an amazing 631 km (391 miles), leaving Texas, crossing over the panhandle of Oklahoma and winding up well north into Kansas. Don McCall comments,
"Arena, meanwhile, has set yet another 1-day distance record. Even without including her final position for the day (and she was still flying at 74 km/hr, 46 mph at her late afternoon fix), she had already flown 563 km (349 miles). That speed and distance seem extraordinary, so I looked up a weather map showing prevailing winds. That entire region of the country (she's now in northern Kansas) has had uniformly strong southerly winds around 15-20 knots (this would be a tailwind for Arena). Interestingly, the prevailing wind direction matches Arena's course very closely, slightly east of north. Is she using the tailwind to maximum effect to cover the greatest possible distance while she flies? Or does she really want to be trending slightly eastward now? My wild guess is that she's using the wind and will eventually turn back to the west. We shall see.
Speaking of distances -- Arena has now passed the 6000 mile mark. And she still has a very long way to go. "
At this rate, Arena will be leaving the US in two or three days. Once again, she seems to be making a beeline north.
After her record flight, she slept within an "agricultural circle" near Colby, Kansas, just north of Interstate 70. This site is located about the same latitude as Denver, Colorado. We can't identify any specific roosting structures in this satellite photo either. So it is possible that she may have slept directly on the sprinkler equipment, but again, it is hard to say with any certainty.
F. Prescott Ward, a friend and one of the leading authorities on peregrine migration, has e-mailed us the following comments regarding Arena. I quote with his permission...
"In the 1980's when we were doing peregrine telemetry tracking from Padre Island via fixed-wing aircraft, we found that once an individual bird set a route from Padre, it followed it without deviation to its high Arctic breeding place. In other words, if you got a departure vector from Padre by following the bird for a few hundred miles, you could draw a straight line to her Arctic nest -- 'Arena' seems to have set a vector of about 300 degrees (NNW) and will likely nest in the northern Northwest Territories or Nunavut. We'll see ...
Years ago, we were tracking one female up the Mississippi flyway when a huge storm blew her hundreds of miles west off the 'migration line' she had established (she was headed toward Quebec). She laid up in Missouri for a couple days until the storm passed, then promptly flew east until she intersected her imaginary line, then turned unerringly toward her destination.It'll be interesting to see how much Arena deviates from her 'departure vector'."
Thanks for the insightful comments Scott. We appreciate them.
There are only two band returns from Chile that involve peregrines banded as nestlings. One is from the Bathurst Inlet area in Nunavat, the other from the Northwest Territories. It looks as though she may be headed there as Scott suggests.
The following day (13 May), Arena set a new distance record for the season. She flew an amazing 631 km (391 miles), leaving Texas, crossing over the panhandle of Oklahoma and winding up well north into Kansas. Don McCall comments,
"Arena, meanwhile, has set yet another 1-day distance record. Even without including her final position for the day (and she was still flying at 74 km/hr, 46 mph at her late afternoon fix), she had already flown 563 km (349 miles). That speed and distance seem extraordinary, so I looked up a weather map showing prevailing winds. That entire region of the country (she's now in northern Kansas) has had uniformly strong southerly winds around 15-20 knots (this would be a tailwind for Arena). Interestingly, the prevailing wind direction matches Arena's course very closely, slightly east of north. Is she using the tailwind to maximum effect to cover the greatest possible distance while she flies? Or does she really want to be trending slightly eastward now? My wild guess is that she's using the wind and will eventually turn back to the west. We shall see.
Speaking of distances -- Arena has now passed the 6000 mile mark. And she still has a very long way to go. "
At this rate, Arena will be leaving the US in two or three days. Once again, she seems to be making a beeline north.
After her record flight, she slept within an "agricultural circle" near Colby, Kansas, just north of Interstate 70. This site is located about the same latitude as Denver, Colorado. We can't identify any specific roosting structures in this satellite photo either. So it is possible that she may have slept directly on the sprinkler equipment, but again, it is hard to say with any certainty.
F. Prescott Ward, a friend and one of the leading authorities on peregrine migration, has e-mailed us the following comments regarding Arena. I quote with his permission...
"In the 1980's when we were doing peregrine telemetry tracking from Padre Island via fixed-wing aircraft, we found that once an individual bird set a route from Padre, it followed it without deviation to its high Arctic breeding place. In other words, if you got a departure vector from Padre by following the bird for a few hundred miles, you could draw a straight line to her Arctic nest -- 'Arena' seems to have set a vector of about 300 degrees (NNW) and will likely nest in the northern Northwest Territories or Nunavut. We'll see ...
Years ago, we were tracking one female up the Mississippi flyway when a huge storm blew her hundreds of miles west off the 'migration line' she had established (she was headed toward Quebec). She laid up in Missouri for a couple days until the storm passed, then promptly flew east until she intersected her imaginary line, then turned unerringly toward her destination.It'll be interesting to see how much Arena deviates from her 'departure vector'."
Thanks for the insightful comments Scott. We appreciate them.
There are only two band returns from Chile that involve peregrines banded as nestlings. One is from the Bathurst Inlet area in Nunavat, the other from the Northwest Territories. It looks as though she may be headed there as Scott suggests.
May 11, 2007
Arena Enters the United States
After spending several days around the dunes near Veracruz, apparently fattening up and resting, Arena started north again in a serious fashion. She flew up the Gulf of Mexico coastline covering 399 km (248 miles) in a day and crossing the Tropic of Cancer. She flew inland to roost and selected a grove of trees in the coastal hills. I drove through this area last fall and it is beautiful with rolling hills and lush green forest.
Yesterday, Arena turned on the speed and flew a record 537.1 km (333 miles) north, entering the US in the afternoon and roosting SE of Laredo. Surprisingly, she chose an inland route and bypassed Padre Island completely. We were all hoping she would stop off there but she obviously has her own agenda and is totally immune to our preferences. She roosted in a south Texas oilfield as you can see from all of the roads and drilling sites.
It appears that Arena is starting to increase her speed now that she is getting closer to her eyrie or nest site.I am wondering if her inland direction indicates she will head in a more westerly direction from here. Only time will tell.
Yesterday, Arena turned on the speed and flew a record 537.1 km (333 miles) north, entering the US in the afternoon and roosting SE of Laredo. Surprisingly, she chose an inland route and bypassed Padre Island completely. We were all hoping she would stop off there but she obviously has her own agenda and is totally immune to our preferences. She roosted in a south Texas oilfield as you can see from all of the roads and drilling sites.
It appears that Arena is starting to increase her speed now that she is getting closer to her eyrie or nest site.I am wondering if her inland direction indicates she will head in a more westerly direction from here. Only time will tell.
May 7, 2007
Comments on Panama by Karl Kaufmann
Karl Kaufmann of the Panama Audubon Society sent these comments to us this morning.
"I've often seen Peregrines harassing the shorebirds at the Upper Bay of Panama WHSRN site where I live. This site is a stretch of mudflats and mangroves extending from Panama City for 70 km to the east. During spring and fall migration it hosts from 1,000,000 to 2,000,000 shorebirds, the great majority being Western Sandpipers. Migration is now over, but there is still a substantial population of first year Western Sandpipers that do not migrate, and moderate quantities of larger shorebirds. Last April I counted a flock of about 25,000 peeps there. When the tide is low, the birds are spread thinly over the mudflats that are up to 2 km wide, but when the tide gets to be over 400cm ( I guess the 0 datum is MLWS), the birds are concentrated in a band of mud about 100 m wide and above 500cm the birds often have to come ashore to roost. It is during these spring tides that we see the falcons flying over the flocks. Perhaps it is just as easy for a falcon to catch a shorebird when it is isolated on the mudflats at low tide as when it it in a flock of thousands. Do you know which part of the tidal cycle they prefer? I suspect they have better success when the birds are concentrated, and if they do, you could make an estimate of the probability of the falcon catching prey by knowing the state of the tide and the location of the shorebirds.
In the case of Arena, she was at Punta Garachine at 5PM EST (22 UTC) on April 20 after flying along a stretch of coast bordered by mountains and no mudflats. Behind Punta Garachine is an extensive mudflat, and an above average spring high tide of 511cm was due at 6:03 PM. (These times and heights are all based on the Naos tide table near Panama City, but the times are within a few minutes of each other along the entire coast and the heights are similar). So whatever birds are there at that time, probably a few small sandpipers, medium sized dowitchers, and larger Willets, and Whimbrels, were concentrated on the mud from about 4PM on. I've never been there so I don't know for sure. So there might have been an opportunity for a meal of shorebirds, but then she roosted for the night another 42 km further along the coast at a spot about 10 km from the closest mud-flat. The next morning high tide was at 6:37 AM so again there was a chance to catch a shorebird, if she does in fact like catching them near high tide. That afternoon she apparently flew right over the mudflats close to Panama City, the most heavily used part of the UBP site during migration, but was well past the coast by 5PM, about 2 hours before high tide at 6:53PM. So she was probably not at the coast at the time the birds were most concentrated. She then spent the next two days around forested areas or on the Caribbean coast where there are far fewer shorebirds. On April 24 and 25 she was near Punta Chame on the Pacific side but the tides were not particularly high, only 387 and 370cm, so there were probably not any times when shorebirds would have been concentrated along the shore. The rest of the time in Panama was spent either in the mountains or along the Caribbean coast.
Karl Kaufmann
Panama Audubon Society"
Always nice to know what is going on locally. Thank you for the comments Karl.
.
"I've often seen Peregrines harassing the shorebirds at the Upper Bay of Panama WHSRN site where I live. This site is a stretch of mudflats and mangroves extending from Panama City for 70 km to the east. During spring and fall migration it hosts from 1,000,000 to 2,000,000 shorebirds, the great majority being Western Sandpipers. Migration is now over, but there is still a substantial population of first year Western Sandpipers that do not migrate, and moderate quantities of larger shorebirds. Last April I counted a flock of about 25,000 peeps there. When the tide is low, the birds are spread thinly over the mudflats that are up to 2 km wide, but when the tide gets to be over 400cm ( I guess the 0 datum is MLWS), the birds are concentrated in a band of mud about 100 m wide and above 500cm the birds often have to come ashore to roost. It is during these spring tides that we see the falcons flying over the flocks. Perhaps it is just as easy for a falcon to catch a shorebird when it is isolated on the mudflats at low tide as when it it in a flock of thousands. Do you know which part of the tidal cycle they prefer? I suspect they have better success when the birds are concentrated, and if they do, you could make an estimate of the probability of the falcon catching prey by knowing the state of the tide and the location of the shorebirds.
In the case of Arena, she was at Punta Garachine at 5PM EST (22 UTC) on April 20 after flying along a stretch of coast bordered by mountains and no mudflats. Behind Punta Garachine is an extensive mudflat, and an above average spring high tide of 511cm was due at 6:03 PM. (These times and heights are all based on the Naos tide table near Panama City, but the times are within a few minutes of each other along the entire coast and the heights are similar). So whatever birds are there at that time, probably a few small sandpipers, medium sized dowitchers, and larger Willets, and Whimbrels, were concentrated on the mud from about 4PM on. I've never been there so I don't know for sure. So there might have been an opportunity for a meal of shorebirds, but then she roosted for the night another 42 km further along the coast at a spot about 10 km from the closest mud-flat. The next morning high tide was at 6:37 AM so again there was a chance to catch a shorebird, if she does in fact like catching them near high tide. That afternoon she apparently flew right over the mudflats close to Panama City, the most heavily used part of the UBP site during migration, but was well past the coast by 5PM, about 2 hours before high tide at 6:53PM. So she was probably not at the coast at the time the birds were most concentrated. She then spent the next two days around forested areas or on the Caribbean coast where there are far fewer shorebirds. On April 24 and 25 she was near Punta Chame on the Pacific side but the tides were not particularly high, only 387 and 370cm, so there were probably not any times when shorebirds would have been concentrated along the shore. The rest of the time in Panama was spent either in the mountains or along the Caribbean coast.
Karl Kaufmann
Panama Audubon Society"
Always nice to know what is going on locally. Thank you for the comments Karl.
.
Arena in Veracruz
Arena is continuing to teach us about peregrine migration behavior in the most fascinating ways. At last report, she was roosting on some sort of structure in the Gulf of Mexico. Christian Gonzalez writes,
"Many thanks for the info..I´ve been talking to some Mexican friends, and they say that there are oil platforms out there. There are also several Petromex ports on the coast of that area which means that there are platforms in a regular distribution off shore. I´m confirming that with Mexican friends, one is ready to go and check the passage of Arena near Veracruz".
The transmitter altimeter indicates heights of 36m (118 feet) and 96m (316 feet), so if the readings are accurate, she was on a quite a tall object. Her speed was 0 in both readings indicating that she was perched there.
The following morning (5 May), she got an early start as she was flying west over the Gulf of Mexico at 83 kmh(50 mph)and an elevation of 204 feet by 0900. She continued to fly west all the way to the coast of Veracruz. We don't know exactly where she made landfall but by 5 PM local time she was perched on the famous coastal dune fields north of Veracruz. If she flew over water the entire way, then her maximum distance for the day was 392 km (245 miles). Keep in mind that it is equally possible that she put ashore further south and then flew up the coastline over the city of Veracruz.
At any rate and by any direction, she arrived at a remarkable and perfect place to stop. She is now perching in the region of the largest raptor migration in the world, the famous Veracruz River of Raptors discovered and developed by Ernesto Ruelas and the ProNatura organization of Mexico. Each fall, over 4 million raptors pass this location and are counted by the experienced and dedicated crews of the project. It is a spectacle unmatched anywhere else on earth and well worth a visit to witness and experience this unforgettable migration. I am hoping that Ernesto or Norma Ferriz may contribute some insights to the area for us.
So Arena selected this famous coastal dune system lying north of the city of Veracruz. For those of you that have been to Cardel to watch the migration in fall, the dunes are visible to the NE from the top of the Hotel Bienvenido, one of the main observation points for the migration.
This extensive dune system is bisected by an east-west road known to all Veracruz hawk migration visitors. It leads to Playa Juan Angel (Johnny Angel Beach)on the Gulf Coast, a standard stop on most raptor and birding tours in the Veracruz area. The main draw here is Aplomado Falcons, a rare bird for northern hawkwatchers.
I have been to this site many times and it is amazing to think about having been in the same area with my friend, Bill Clark, just last October. We watched several Aplomado Falcons chasing each other where Arena was now perching.
This is one of the first extensive sand-dune areas that she will encounter if she continues on her way up the Gulf coast. She is "in the pipeline" to reach the extensive dune systems and barrier islands of Padre Island, Texas, to the north. Padre is one of the most famous peregrine migration points in the world and she is heading right for it.
Once again, Arena has passed into a new time zone as she gradually moves west. She is now in the US Central Time Zone. I should point out that when you click on one of her GPS points on Google Earth and a data box opens up, please keep in mind that all of her siganls are still coming in at the same time of day, i.e. one at 0100, the second at 0900 and the third at 1500. We programmed them in this way so we would always have a roost site, a morning location and an evening location. Even though she changes time zones, the signals are generated at the same time locally.
Finally, I am reminded that the elevations shown in the data boxes are in meters, not feet. I apologize if I have made any errors.
"Many thanks for the info..I´ve been talking to some Mexican friends, and they say that there are oil platforms out there. There are also several Petromex ports on the coast of that area which means that there are platforms in a regular distribution off shore. I´m confirming that with Mexican friends, one is ready to go and check the passage of Arena near Veracruz".
The transmitter altimeter indicates heights of 36m (118 feet) and 96m (316 feet), so if the readings are accurate, she was on a quite a tall object. Her speed was 0 in both readings indicating that she was perched there.
The following morning (5 May), she got an early start as she was flying west over the Gulf of Mexico at 83 kmh(50 mph)and an elevation of 204 feet by 0900. She continued to fly west all the way to the coast of Veracruz. We don't know exactly where she made landfall but by 5 PM local time she was perched on the famous coastal dune fields north of Veracruz. If she flew over water the entire way, then her maximum distance for the day was 392 km (245 miles). Keep in mind that it is equally possible that she put ashore further south and then flew up the coastline over the city of Veracruz.
At any rate and by any direction, she arrived at a remarkable and perfect place to stop. She is now perching in the region of the largest raptor migration in the world, the famous Veracruz River of Raptors discovered and developed by Ernesto Ruelas and the ProNatura organization of Mexico. Each fall, over 4 million raptors pass this location and are counted by the experienced and dedicated crews of the project. It is a spectacle unmatched anywhere else on earth and well worth a visit to witness and experience this unforgettable migration. I am hoping that Ernesto or Norma Ferriz may contribute some insights to the area for us.
So Arena selected this famous coastal dune system lying north of the city of Veracruz. For those of you that have been to Cardel to watch the migration in fall, the dunes are visible to the NE from the top of the Hotel Bienvenido, one of the main observation points for the migration.
This extensive dune system is bisected by an east-west road known to all Veracruz hawk migration visitors. It leads to Playa Juan Angel (Johnny Angel Beach)on the Gulf Coast, a standard stop on most raptor and birding tours in the Veracruz area. The main draw here is Aplomado Falcons, a rare bird for northern hawkwatchers.
I have been to this site many times and it is amazing to think about having been in the same area with my friend, Bill Clark, just last October. We watched several Aplomado Falcons chasing each other where Arena was now perching.
This is one of the first extensive sand-dune areas that she will encounter if she continues on her way up the Gulf coast. She is "in the pipeline" to reach the extensive dune systems and barrier islands of Padre Island, Texas, to the north. Padre is one of the most famous peregrine migration points in the world and she is heading right for it.
Once again, Arena has passed into a new time zone as she gradually moves west. She is now in the US Central Time Zone. I should point out that when you click on one of her GPS points on Google Earth and a data box opens up, please keep in mind that all of her siganls are still coming in at the same time of day, i.e. one at 0100, the second at 0900 and the third at 1500. We programmed them in this way so we would always have a roost site, a morning location and an evening location. Even though she changes time zones, the signals are generated at the same time locally.
Finally, I am reminded that the elevations shown in the data boxes are in meters, not feet. I apologize if I have made any errors.
May 5, 2007
Arena in Mexico
Arena had a record day yesterday. She flew north from her roost in Nicaragua and crossed Guatemala in a single day, continuing on to the Gulf coast in Campeche, Mexico. She roosted on the south end of the largest bay on the Yucatan coast, the Laguna de Terminos. During her flight, she covered an incredible 543 km (337 miles) in a single day, so her pace is quickening as she moves north.
The following day, she flew over the Gulf of Mexico. The signal indicates that she stopped somewhere at 31 km (22 miles) offshore. Although I checked the Google Earth image of the area, I could not see any oil drilling platforms there. Migrant peregrines are often sighted using these structures as perches in the Gulf. I can easily imagine that she might have landed on a ship, perhaps to enjoy a morning meal. But, of course, we'll never know for certain.
The following day, she flew over the Gulf of Mexico. The signal indicates that she stopped somewhere at 31 km (22 miles) offshore. Although I checked the Google Earth image of the area, I could not see any oil drilling platforms there. Migrant peregrines are often sighted using these structures as perches in the Gulf. I can easily imagine that she might have landed on a ship, perhaps to enjoy a morning meal. But, of course, we'll never know for certain.
May 3, 2007
Arena in Honduras
Arena is moving strongly once again. She has left Costa Rica, traversed Nicaragua and roosted in Honduras last night.
From Costa Rica, Marco Saborio has added some new information, including digital pictures, on her movements there. He writes...
"Hi All,
I know Don kept you very well informed of whatever happened here in Costa Rica the past weekend, but I want to explain in more detail what happened in the field. It is so unfortunate that Arena decided to have a long stay in Panama and just two nights here.
As Don explained before, on April 30th, I started driving at 3:15 AM (local time) to the location where Arena was roosting. The coordinates indicated 134 kms from my home and turned into a 187 kms drive and 2 hours and 34 minutes. I arrived at the location at 5:50. It was very clear and I had seen some Turkey Vultures and Crested Caracaras already flying by 5:30, which surprised me, but then I realized that at this time of the year the sun rises earlier.
When my two GPS units indicated I had arrived to the site, I was exactly in front of this tall Ceibo tree on a little hill of an open area in a farm. The GPS indicated that I was around 600 meters from the reference, which ended to be some 300 meters behind that tree.
I moved a little bit backward and forward observing carefully in all the trees in this area, but did not find any perching raptors and the only birds flying were Vultures, Swifts and parrots. This picture shows a little bit more of the area having the Ceibo tree as reference (right) and in dark green in the back ground the forest on the other side of the Corobici river which runs very close to the road.
This area is very close to the city of Canas which is located by the Pan-American road and this other roads goes to the town of Upala at the base of the Tenorio Volcano (in the background). Next step was to get permission to enter the farm to be able to get to the real reference. Once this was solved I walked into the farm and the GPS took me to the back of the hill where the river canyon was seen more clearly. The isolated tree at right (blue arrow) was the final point, at the edge of the canyon in an even more open area that had been subject to controlled burning.
In this place I found a worker that had arrived there at 5:30 AM to remove some bushes with his machete. I interviewed him but he had not seen any raptors there. After doing walking around observing and talking to Don about my plans to stay in the area I abandoned the place at 11:00 AM.
Next step was to wait for information about any new roosting place for Arena on that day, and try again to find her. Since no information was received by 4:00 AM next day I drove back home. Around 11:00 AM, I received a call from Don with the coordinates of the roosting place for the previous night. I explained to him that even when there is a road marked in the map, it is a very bad one. But here comes a happy coincidence, I had been in that area in April looking for whales and photographing some interesting formation in the rocks there. The following picture shows how is the area Arena where was roosting for the last time in Costa Rica.
The following map fragment shows my boat track and the exact place where the picture was taken (10.56.944N,-85.50.882) and Arena's roost place according to information provided by Don.
I hope some of the six other falcons still on their way North will give me a better chance to find at least one of them. But if at least I can provide information to you on the areas they visit I'll be very pleased to do it.
Best,
Marco T. SaboríoApartado 292-2300,San José, Costa Rica.Tel: (506) 253-1738Cel: (506) 361-7803Fax: (506) 224-7091msaborio@conexion.co.cr"
I think that Marco's e-mail is a perfect example of what we can all achieve by working together. It allows everyone with an interest in migrant peregrines to see and to understand more and more about their incredible stories in each country. This is one of the major goals of our work and we'd like to encourage other peregrine people in these countries to contribute to this effort. So, once again, thanks go to Marco and his great efforts.
Personally, I really enjoyed seeing the habitat in his pictures, particularly the remarkable Punta Santa Elena, her last roost site in Costa Rica. I had no idea that this area (a National Park) even existed and what a beautiful place it is. Now I have to go there and see it someday.
From Santa Elena, Arena went on another completely unexpected flight. This time she flew 65 km (40 miles) SW out over the Pacific Ocean. We have no idea why she did this. We can speculate that she was continuing on her most recent westerly heading. We can suggest that perhaps she was hunting out to sea. We can even guess that she might have landed on a ship. Equally plausible, she may have just plain flown the wrong way. At any rate, she later changed course and flew north. Did she somehow "realize" her error or was this just a normal part of her flight? There are still so many unanswered questions.
Of course, the hard data like these are great teachers and show us what we need to be thinking about next. In looking at the detailed GPS locations, for example, I have come to realize that I've always had the unconscious idea that peregrines migrated unerringly and in the absolute optimal direction. Sort of like they always select the straightest distance between two points. Well, this is certainly not what we are seeing. In fact, I have been amazed at how Arena is sort of bouncing back and forth between the two coastlines of Central America. The general trend is there but the detailed movements do not follow the optimal line. So it is really wonderful to see the reality of peregrine migration and have to identify and give up my erroneous ideas. And I think that is one of the most wonderful things about field biology and science in general. We continue to learn new facts, discard old prejudices and then develop new ways of looking at the world.
So Arena corrected her course and again flew north, crossing the border into Nicaragua. Once again, she flew inland from the coastline, traversing the lower slopes of a mountain range. Check out the mountain town of Diriamba (1,800 feet) above her route. It appears that she might have been gaining lift from the onshore flow of air up the mountains situated between the ocean and Lake Nicaragua.
She continued north and roosted approximately 41 km (25 miles) west of the capitol city of Managua. From the Google Earth image, it looks like she selected a tree in some pretty dry forest. The elevation was around 100 meters(300 feet).
Yesterday, she started her day by flying 12 km (7 miles) down to the Pacific coastline. Knowing peregrines, it is a good bet that she went there to hunt but we can't know for certain. The Google Earth image shows her at a gorgeous coastal estuary with beaches, an extensive lagoon, dunes and forest, all providing perfect habitat for her prey, especially shorebirds.
From there, she flew strongly to the NW and by 4 PM local time had covered 302 km (187 miles). Her line crossed the Bay of Fonseca, where three countries come together, El Salvador, Honduras and Nicaragua. She may have passed over this area but then moved inland behind the coastal range. So last night, she was in western Honduras and closing in rapidly on Guatemala.
I would like to ask for some assistance from our readership at this point. We would very much like to make contact any raptor people in Honduras, El Salvador and Nicaragua. If anyone reading this post has colleagues or co-workers living there, please let us know so we can expand our network of friends. Thanks.
From Costa Rica, Marco Saborio has added some new information, including digital pictures, on her movements there. He writes...
"Hi All,
I know Don kept you very well informed of whatever happened here in Costa Rica the past weekend, but I want to explain in more detail what happened in the field. It is so unfortunate that Arena decided to have a long stay in Panama and just two nights here.
As Don explained before, on April 30th, I started driving at 3:15 AM (local time) to the location where Arena was roosting. The coordinates indicated 134 kms from my home and turned into a 187 kms drive and 2 hours and 34 minutes. I arrived at the location at 5:50. It was very clear and I had seen some Turkey Vultures and Crested Caracaras already flying by 5:30, which surprised me, but then I realized that at this time of the year the sun rises earlier.
When my two GPS units indicated I had arrived to the site, I was exactly in front of this tall Ceibo tree on a little hill of an open area in a farm. The GPS indicated that I was around 600 meters from the reference, which ended to be some 300 meters behind that tree.
I moved a little bit backward and forward observing carefully in all the trees in this area, but did not find any perching raptors and the only birds flying were Vultures, Swifts and parrots. This picture shows a little bit more of the area having the Ceibo tree as reference (right) and in dark green in the back ground the forest on the other side of the Corobici river which runs very close to the road.
This area is very close to the city of Canas which is located by the Pan-American road and this other roads goes to the town of Upala at the base of the Tenorio Volcano (in the background). Next step was to get permission to enter the farm to be able to get to the real reference. Once this was solved I walked into the farm and the GPS took me to the back of the hill where the river canyon was seen more clearly. The isolated tree at right (blue arrow) was the final point, at the edge of the canyon in an even more open area that had been subject to controlled burning.
In this place I found a worker that had arrived there at 5:30 AM to remove some bushes with his machete. I interviewed him but he had not seen any raptors there. After doing walking around observing and talking to Don about my plans to stay in the area I abandoned the place at 11:00 AM.
Next step was to wait for information about any new roosting place for Arena on that day, and try again to find her. Since no information was received by 4:00 AM next day I drove back home. Around 11:00 AM, I received a call from Don with the coordinates of the roosting place for the previous night. I explained to him that even when there is a road marked in the map, it is a very bad one. But here comes a happy coincidence, I had been in that area in April looking for whales and photographing some interesting formation in the rocks there. The following picture shows how is the area Arena where was roosting for the last time in Costa Rica.
The following map fragment shows my boat track and the exact place where the picture was taken (10.56.944N,-85.50.882) and Arena's roost place according to information provided by Don.
I hope some of the six other falcons still on their way North will give me a better chance to find at least one of them. But if at least I can provide information to you on the areas they visit I'll be very pleased to do it.
Best,
Marco T. SaboríoApartado 292-2300,San José, Costa Rica.Tel: (506) 253-1738Cel: (506) 361-7803Fax: (506) 224-7091msaborio@conexion.co.cr"
I think that Marco's e-mail is a perfect example of what we can all achieve by working together. It allows everyone with an interest in migrant peregrines to see and to understand more and more about their incredible stories in each country. This is one of the major goals of our work and we'd like to encourage other peregrine people in these countries to contribute to this effort. So, once again, thanks go to Marco and his great efforts.
Personally, I really enjoyed seeing the habitat in his pictures, particularly the remarkable Punta Santa Elena, her last roost site in Costa Rica. I had no idea that this area (a National Park) even existed and what a beautiful place it is. Now I have to go there and see it someday.
From Santa Elena, Arena went on another completely unexpected flight. This time she flew 65 km (40 miles) SW out over the Pacific Ocean. We have no idea why she did this. We can speculate that she was continuing on her most recent westerly heading. We can suggest that perhaps she was hunting out to sea. We can even guess that she might have landed on a ship. Equally plausible, she may have just plain flown the wrong way. At any rate, she later changed course and flew north. Did she somehow "realize" her error or was this just a normal part of her flight? There are still so many unanswered questions.
Of course, the hard data like these are great teachers and show us what we need to be thinking about next. In looking at the detailed GPS locations, for example, I have come to realize that I've always had the unconscious idea that peregrines migrated unerringly and in the absolute optimal direction. Sort of like they always select the straightest distance between two points. Well, this is certainly not what we are seeing. In fact, I have been amazed at how Arena is sort of bouncing back and forth between the two coastlines of Central America. The general trend is there but the detailed movements do not follow the optimal line. So it is really wonderful to see the reality of peregrine migration and have to identify and give up my erroneous ideas. And I think that is one of the most wonderful things about field biology and science in general. We continue to learn new facts, discard old prejudices and then develop new ways of looking at the world.
So Arena corrected her course and again flew north, crossing the border into Nicaragua. Once again, she flew inland from the coastline, traversing the lower slopes of a mountain range. Check out the mountain town of Diriamba (1,800 feet) above her route. It appears that she might have been gaining lift from the onshore flow of air up the mountains situated between the ocean and Lake Nicaragua.
She continued north and roosted approximately 41 km (25 miles) west of the capitol city of Managua. From the Google Earth image, it looks like she selected a tree in some pretty dry forest. The elevation was around 100 meters(300 feet).
Yesterday, she started her day by flying 12 km (7 miles) down to the Pacific coastline. Knowing peregrines, it is a good bet that she went there to hunt but we can't know for certain. The Google Earth image shows her at a gorgeous coastal estuary with beaches, an extensive lagoon, dunes and forest, all providing perfect habitat for her prey, especially shorebirds.
From there, she flew strongly to the NW and by 4 PM local time had covered 302 km (187 miles). Her line crossed the Bay of Fonseca, where three countries come together, El Salvador, Honduras and Nicaragua. She may have passed over this area but then moved inland behind the coastal range. So last night, she was in western Honduras and closing in rapidly on Guatemala.
I would like to ask for some assistance from our readership at this point. We would very much like to make contact any raptor people in Honduras, El Salvador and Nicaragua. If anyone reading this post has colleagues or co-workers living there, please let us know so we can expand our network of friends. Thanks.
May 1, 2007
Arena Migrates Through Costa Rica
After spending five days in Panama, Arena began moving again last week. On Friday, she committed to her current flight line and flew to the west, thereby selecting the direction that will take her up through Central America. By that evening, she had reached the Caribbean coastline and roosted there. She covered 144 km (89 miles) that day, not a great distance but definitely a major change in direction.
The next day, Saturday the 28th, she was moving along the Caribbean coast in the morning and moved inland past the Bocas Del Toro region of Panama. She slept in the forest in a remarkable area of lakes and salt-water bays, her last known site in Panama.
The next day, by 10 AM local time, Arena had entered Costa Rica for the first time this year. She was flying along a well-known raptor migration route on the Caribbean coast and may have passed over the hawk counting station at Kekoldi in the Kekoldi Indigenous Reserve.
At this point, I'd like to mention an important new book written by one of the leading experts on hawk migration, Dr. Keith Bildstein. It is titled Migrating Raptors of the World: Their Ecology and Conservation. It was published last year by Cornell Universtiy Press.
Keith has spent his life studying raptors and is currently the Sarkis Acopian Director of Conservation Science at the Hawk Mountain Sanctuary in Pennsylvania.
He has written an excellent book that covers many of the facets of hawk migration and I would recommned it strongly to any of you that would like to learn more about this subject.
Keith worked with Costa Rican migration expert Marco Saborio in Costa Rica in the spring of 1999. Their intent was to locate a good hawk migration site in that country. They found several but eventually selected the site discovered earlier by Charles Duncan and Pablo Porras. Sponsored by the Costa Rican Asociacion ANAI and Hawk Mountain this eventually morphed into the Kekoldi raptor count site. Keith provides an excellent description of the history and location in his new book.
In terms of the total counts, Kekoldi is one of the top three hawk migration sites in the world. Over a million raptors pass by the lookout each year. Keith reports that it is also one of the best places to see migrant peregrines in the world.
So it is not surprising that Arena passed along this coastline last Sunday. We had hoped that the counters might have seen her but no such luck.
Earlier, Keith had suggested that we contact his friend, Marco Saborio, so we did. We found that Marco had a strong interest in this satellite tagged peregrine flying through his country. So we established a working relationship and decided to see if he could intercept Arena on her flight through Costa Rica.
On Sunday he wrote "I just got a report from Kekoldi raptor counting site, 13 Peregrines have passed this morning from 700 to 1100 (local time: GMT -6), eleven of them in the last hour (1000 to 1100). Unfortunately none was identified as Arena, lets see what happen this afternoon."
This is a pretty high number of peregrines so late in the season. It adds support to Tom Maechtle's theory that alot of spring migrant peregrines are missed at Padre Island, Texas, in May. The banding study there has traditionally ended by 1 May and therefore would not have documented this May passage.
We suspect that the majority of these late migrating peregrines would be "deep" falcons, birds that "winter" south of the Tropic of Capricorn in South America.
Back to Marco Saborio. When the GPS data comes in here each day, Don McCall is the first team member to see it. So Don and Marco started working together to see if they could intercept Arena in Costa Rica. Marco positioned himself along her tentative route. Calling each other by cell phone at all hours of the night, Marco made an excellent attempt to see her on Monday morning.
In the meantime, Arena had left the Caribbean coast and flown due west towards the Pacific. She crossed over the chain of volcanos that extend through northern Costa Rica and eventually landed just west of Lago Arenal.
Marco made a pre-dawn dash for her roost site. Don reports that...
"I just spoke again with Marco Saborio in Costa Rica. The 0600Z GPS fix (10.51333, -85.11283) led him to a specific tree in an open farm field near a river, but the sky was already becoming light when he arrived, no bird was in sight, and a farm worker had arrived a few minutes earlier; Marco wonders if the arrival of the worker caused the bird to fly away, because there wasn't a lot of other cover around. He said it was raining in the hills which would probably drive Arena toward the beach in the west. "
Don later added...
"Marco just called again. He thinks there's a chance that Arena might stay near the beach tonight, inside Costa Rica, so he's going to get a hotel room in a nearby town and we'll stay in touch tonight for another attempt. He wants to try to get to her position while it's still dark, if possible. Of course I'll call him immediately if we learn that she has continued north into Nicaragua."
Unfortunately, despite a great attempt, the bird evaded Marco's efforts. We all thank him for trying. It's wonderful to have new friends in far away places.
So Arena is migrating once more and looks to be headed for the Pacific coastline. She made the necessary change in course and completed the western component of the Central American route. Now we will see how she proceeds through what Keith calls the "Meso-American land bridge".
The next day, Saturday the 28th, she was moving along the Caribbean coast in the morning and moved inland past the Bocas Del Toro region of Panama. She slept in the forest in a remarkable area of lakes and salt-water bays, her last known site in Panama.
The next day, by 10 AM local time, Arena had entered Costa Rica for the first time this year. She was flying along a well-known raptor migration route on the Caribbean coast and may have passed over the hawk counting station at Kekoldi in the Kekoldi Indigenous Reserve.
At this point, I'd like to mention an important new book written by one of the leading experts on hawk migration, Dr. Keith Bildstein. It is titled Migrating Raptors of the World: Their Ecology and Conservation. It was published last year by Cornell Universtiy Press.
Keith has spent his life studying raptors and is currently the Sarkis Acopian Director of Conservation Science at the Hawk Mountain Sanctuary in Pennsylvania.
He has written an excellent book that covers many of the facets of hawk migration and I would recommned it strongly to any of you that would like to learn more about this subject.
Keith worked with Costa Rican migration expert Marco Saborio in Costa Rica in the spring of 1999. Their intent was to locate a good hawk migration site in that country. They found several but eventually selected the site discovered earlier by Charles Duncan and Pablo Porras. Sponsored by the Costa Rican Asociacion ANAI and Hawk Mountain this eventually morphed into the Kekoldi raptor count site. Keith provides an excellent description of the history and location in his new book.
In terms of the total counts, Kekoldi is one of the top three hawk migration sites in the world. Over a million raptors pass by the lookout each year. Keith reports that it is also one of the best places to see migrant peregrines in the world.
So it is not surprising that Arena passed along this coastline last Sunday. We had hoped that the counters might have seen her but no such luck.
Earlier, Keith had suggested that we contact his friend, Marco Saborio, so we did. We found that Marco had a strong interest in this satellite tagged peregrine flying through his country. So we established a working relationship and decided to see if he could intercept Arena on her flight through Costa Rica.
On Sunday he wrote "I just got a report from Kekoldi raptor counting site, 13 Peregrines have passed this morning from 700 to 1100 (local time: GMT -6), eleven of them in the last hour (1000 to 1100). Unfortunately none was identified as Arena, lets see what happen this afternoon."
This is a pretty high number of peregrines so late in the season. It adds support to Tom Maechtle's theory that alot of spring migrant peregrines are missed at Padre Island, Texas, in May. The banding study there has traditionally ended by 1 May and therefore would not have documented this May passage.
We suspect that the majority of these late migrating peregrines would be "deep" falcons, birds that "winter" south of the Tropic of Capricorn in South America.
Back to Marco Saborio. When the GPS data comes in here each day, Don McCall is the first team member to see it. So Don and Marco started working together to see if they could intercept Arena in Costa Rica. Marco positioned himself along her tentative route. Calling each other by cell phone at all hours of the night, Marco made an excellent attempt to see her on Monday morning.
In the meantime, Arena had left the Caribbean coast and flown due west towards the Pacific. She crossed over the chain of volcanos that extend through northern Costa Rica and eventually landed just west of Lago Arenal.
Marco made a pre-dawn dash for her roost site. Don reports that...
"I just spoke again with Marco Saborio in Costa Rica. The 0600Z GPS fix (10.51333, -85.11283) led him to a specific tree in an open farm field near a river, but the sky was already becoming light when he arrived, no bird was in sight, and a farm worker had arrived a few minutes earlier; Marco wonders if the arrival of the worker caused the bird to fly away, because there wasn't a lot of other cover around. He said it was raining in the hills which would probably drive Arena toward the beach in the west. "
Don later added...
"Marco just called again. He thinks there's a chance that Arena might stay near the beach tonight, inside Costa Rica, so he's going to get a hotel room in a nearby town and we'll stay in touch tonight for another attempt. He wants to try to get to her position while it's still dark, if possible. Of course I'll call him immediately if we learn that she has continued north into Nicaragua."
Unfortunately, despite a great attempt, the bird evaded Marco's efforts. We all thank him for trying. It's wonderful to have new friends in far away places.
So Arena is migrating once more and looks to be headed for the Pacific coastline. She made the necessary change in course and completed the western component of the Central American route. Now we will see how she proceeds through what Keith calls the "Meso-American land bridge".
April 27, 2007
Raining in Panama
Arena is still holding up in Panama although she is moving short distances around the country. Today, I received this e-mail from our colleague, Marco Saborio, in Costa Rica. He writes....
"The weather here and in Panama has changed in the last two days. We are having rain all around the country. I don't know how this will affect the advance of Arena, my experience with other raptors is that they will stop. However, this morning three Peregrines flew over Kekoldi [a hawkwatching site in Costa Rica] under light rain. I think the rains could stay for the next two days, I hope I'm wrong."
This is a really good example of what we would like to create for this project, a network of raptor people in each of the countries along the Pacific coast of the western hemisphere. Marco has contributed a timely observation about what is currently happening in his geographic area. Arena's slowdown makes more sense to us all now.
It is fun to sit at a computer and speculate endlessly about what is going on with these birds but obviously, nothing beats someone being there "on the ground" with them.
Thanks for the post Marco. We all appreciate it.
"The weather here and in Panama has changed in the last two days. We are having rain all around the country. I don't know how this will affect the advance of Arena, my experience with other raptors is that they will stop. However, this morning three Peregrines flew over Kekoldi [a hawkwatching site in Costa Rica] under light rain. I think the rains could stay for the next two days, I hope I'm wrong."
This is a really good example of what we would like to create for this project, a network of raptor people in each of the countries along the Pacific coast of the western hemisphere. Marco has contributed a timely observation about what is currently happening in his geographic area. Arena's slowdown makes more sense to us all now.
It is fun to sit at a computer and speculate endlessly about what is going on with these birds but obviously, nothing beats someone being there "on the ground" with them.
Thanks for the post Marco. We all appreciate it.
April 26, 2007
Arena pauses on migration
Arena is remaining in Panama for the moment, apparently taking a break from her northern migration.
In 1980, Grainger Hunt, Brenda Johnson and Scott Ward discovered that spring migrant peregrines were pausing at Padre Island, Texas, for varying amounts of time. Using tail-mounted transmitters and a Cessna airplane, Grainger and Brenda found that some individual falcons stayed at the island for up to a month before proceeding north. Grainger theorized that the falcons were fattening up on Gulf migrants so they could produce the best eggs possible. I also thought that there was great value in laying on fat reserves before arriving at their eyries (nests). The females will have to set and incubate/brood for 7 weeks in the arctic, perhaps experiencing the coldest temperatures of their annual cycle. The extra fat could provide more energy to keep them warm during incubation.
So Arena is now "staging" in Panama. Her signals show that she is hanging out at a large bay on the south shore of Panama. It has a strand of sandy beach bordered by an enormous mudfalt, in some places extending a full mile out into the Pacific.
In my experience, extensive mudflats in spring mean large numbers of shorebirds. So we can speculate that she is likely there feeding up on migrants or some other prey species unknown to us at this point.
We'd love to hear from anyone in Panama that might be able to confirm this idea.Also keep in mind that she just migrated nearly 5,000 km and has expended alot of energy to get to Panama. It would be most interesting to compare her weight when we caught her in Chile with her weight now. How much, if any, body mass has she lost on her flight north?
The Google Earth image suggests that she roosted in a grove of trees on a low ridge near, perhaps overlooking, the bay.
In 1980, Grainger Hunt, Brenda Johnson and Scott Ward discovered that spring migrant peregrines were pausing at Padre Island, Texas, for varying amounts of time. Using tail-mounted transmitters and a Cessna airplane, Grainger and Brenda found that some individual falcons stayed at the island for up to a month before proceeding north. Grainger theorized that the falcons were fattening up on Gulf migrants so they could produce the best eggs possible. I also thought that there was great value in laying on fat reserves before arriving at their eyries (nests). The females will have to set and incubate/brood for 7 weeks in the arctic, perhaps experiencing the coldest temperatures of their annual cycle. The extra fat could provide more energy to keep them warm during incubation.
So Arena is now "staging" in Panama. Her signals show that she is hanging out at a large bay on the south shore of Panama. It has a strand of sandy beach bordered by an enormous mudfalt, in some places extending a full mile out into the Pacific.
In my experience, extensive mudflats in spring mean large numbers of shorebirds. So we can speculate that she is likely there feeding up on migrants or some other prey species unknown to us at this point.
We'd love to hear from anyone in Panama that might be able to confirm this idea.Also keep in mind that she just migrated nearly 5,000 km and has expended alot of energy to get to Panama. It would be most interesting to compare her weight when we caught her in Chile with her weight now. How much, if any, body mass has she lost on her flight north?
The Google Earth image suggests that she roosted in a grove of trees on a low ridge near, perhaps overlooking, the bay.
April 23, 2007
Arena sizing things up?
From the signal it appears that Arena spent the night roosting in a tree overlooking the Caribbean Sea. She crossed the Panama Canal yesterday and is just west of the city of Colon, not far from the famous Gatun Locks.
At this point, her northern progress is blocked by the Caribbean. Since she hasn't moved very far in the last two days, it is tempting to speculate that she has been resting up for a major water crossing. We are wondering if she is going to simply head straight north over the sea.
Peregrines are capable of the most amazing over-water travels. For example, a migrant adult was known to have "wintered" every year in the Galapagos Islands, 725 miles offshore from Costa Rica. There is only one island, Cocos Island, between Costa Rica and the Galapagos Islands as a mid-point landfall. The distance from Salinas, Ecuador is 580 miles across the Pacific.
Last year in April, I saw an adult female peregrine fly right in front of me on the Kona side of the big island of Hawaii, 2,330 miles off of the coast of California. Peregrines have been reported from Hawaii many times.
So Arena may be poised for such a flight or she may continue up the Central American corridor, perhaps passing near the Kekoldi hawkwatch site in Costa Rica. Our colleague, Marco Saborio, will be looking for her in his country. Good luck Marco!
At this point, her northern progress is blocked by the Caribbean. Since she hasn't moved very far in the last two days, it is tempting to speculate that she has been resting up for a major water crossing. We are wondering if she is going to simply head straight north over the sea.
Peregrines are capable of the most amazing over-water travels. For example, a migrant adult was known to have "wintered" every year in the Galapagos Islands, 725 miles offshore from Costa Rica. There is only one island, Cocos Island, between Costa Rica and the Galapagos Islands as a mid-point landfall. The distance from Salinas, Ecuador is 580 miles across the Pacific.
Last year in April, I saw an adult female peregrine fly right in front of me on the Kona side of the big island of Hawaii, 2,330 miles off of the coast of California. Peregrines have been reported from Hawaii many times.
So Arena may be poised for such a flight or she may continue up the Central American corridor, perhaps passing near the Kekoldi hawkwatch site in Costa Rica. Our colleague, Marco Saborio, will be looking for her in his country. Good luck Marco!
Linda and Arena - April 23rd
Linda continues to travel up the spine of the Andes Mountains. Yesterday she flew 254 km (158 miles) over the high, dry mountains of the Puna region of Peru. The transmitter indicates that she roosted on a ridge overlooking a deep valley about 18 miles NW of the famous town of Ayacucho, elevation 3,000 meters (9,000 feet). To see the habitat, you can click on the symbols at Ayacucho on Google Earth. You will see brown, dry, rolling hills with little vegetation, again perfect hunting habitat for falcons.
Linda is moving closer to the east side of the Andes now and is only about 60 km (40 miles) from the Amazon basin. You can see the rapid transition to the green tropical forests on the maps.
She is currently about 2,400 km (1,500 miles) behind Arena.
Arena flew 157 km (98 miles) yesterday. She passed along the southern edge of the famous Darien Gap of Panama, the wild and roadless area that still effectively separates the two continents. According to the GPS signal, she winged her way over the eastern outskirts of Panama City at an altitude of 80 meters (250') .
Panama can be incredibly hot and humid. And, as I think about it, it is possible that this may be the warmest area that she will encounter on her migration north. The heat and humidity may have something to do with the relatively short distance that she traveled today.
Arena eventually roosted in the forest overlooking a large lake – Madden Lake. She slept about 20 miles east of the Panama Canal and just south of the Caribbean Sea. I wish I could see exactly what her roost looked like. Was it a tree, cliff, power tower, antenna or what?
We don't think about this much but here she is, dropping out of the sky, looking for a safe place to sleep. She is in a new location, a new habitat, new environmental conditions, new sounds, new predators, new types of trees. And she has to select a roost where she will be safe at night. Maybe the best analogy for us to think about would be arriving in an entirely new country at dusk and trying to find a safe place to stay.
She also has to avoid an entirely new host of predators, many of them arboreal. We're talking everything from snakes and owls to Jaguars. This is one of the reasons that biologists consider migration to be so "expensive". It costs the bird energy to make the long migration and it also exposes them to a much greater risk, as you can understand by imagining Arena tucking up into some giant tree.
In contrast, the peregrines living here in my home town of Seattle (47 N. latitude) don't migrate. They remain here all year and so they are not exposed to the same dangers and costs as Arena.
Her flight path has continued to trend to the northwest but if she wants to migrate up through Central America, she will have to alter her course today. I expect that she will back-track and fly WSW from here. Now let's see what she really does....
Linda is moving closer to the east side of the Andes now and is only about 60 km (40 miles) from the Amazon basin. You can see the rapid transition to the green tropical forests on the maps.
She is currently about 2,400 km (1,500 miles) behind Arena.
Arena flew 157 km (98 miles) yesterday. She passed along the southern edge of the famous Darien Gap of Panama, the wild and roadless area that still effectively separates the two continents. According to the GPS signal, she winged her way over the eastern outskirts of Panama City at an altitude of 80 meters (250') .
Panama can be incredibly hot and humid. And, as I think about it, it is possible that this may be the warmest area that she will encounter on her migration north. The heat and humidity may have something to do with the relatively short distance that she traveled today.
Arena eventually roosted in the forest overlooking a large lake – Madden Lake. She slept about 20 miles east of the Panama Canal and just south of the Caribbean Sea. I wish I could see exactly what her roost looked like. Was it a tree, cliff, power tower, antenna or what?
We don't think about this much but here she is, dropping out of the sky, looking for a safe place to sleep. She is in a new location, a new habitat, new environmental conditions, new sounds, new predators, new types of trees. And she has to select a roost where she will be safe at night. Maybe the best analogy for us to think about would be arriving in an entirely new country at dusk and trying to find a safe place to stay.
She also has to avoid an entirely new host of predators, many of them arboreal. We're talking everything from snakes and owls to Jaguars. This is one of the reasons that biologists consider migration to be so "expensive". It costs the bird energy to make the long migration and it also exposes them to a much greater risk, as you can understand by imagining Arena tucking up into some giant tree.
In contrast, the peregrines living here in my home town of Seattle (47 N. latitude) don't migrate. They remain here all year and so they are not exposed to the same dangers and costs as Arena.
Her flight path has continued to trend to the northwest but if she wants to migrate up through Central America, she will have to alter her course today. I expect that she will back-track and fly WSW from here. Now let's see what she really does....
April 21, 2007
April 21st update
Arena covered 263 km (164 miles) yesterday and officially left South America. She continued to fly well into Panama and the signal shows that she was still migrating after 5 PM local time. You can see that location where she was about a mile offshore and still heading north.
She has made her "decision" to continue migrating up through Central America, at least for awhile, at this point.
If you have never been there, Panama is shaped a bit like a crescent moon on its side. It is actually situated on an east-west axis, not north-south as many people expect. To continue flying north, Arena will actually have to fly west for a bit.
Let's see if she continues flying up the coastline or does a short-cut across the Pacific to the Pearl Islands.
Linda has left the coastal terrace and moved up into the high country of the Andes. She roosted on a ridgeline above a river valley last night. If you have Google Earth, zoom in to this area and you will see why she is there. It is covered with high altitude lakes and ponds. This is very open country and is ideal habitat for peregrines to hunt. These abundant water sources support high populations of prey species. It is likely that some are migrating north with the falcons. Click on some the blue circle icons to see photographs of this remarkable area.
The transmitters are confirming that the high country or Puna area of Peru seems to be quite important for migrating peregrines.
Seven has returned to the coastal route and is moving north at an accelerated rate. He is near Ecuador and should arrive there today.
She has made her "decision" to continue migrating up through Central America, at least for awhile, at this point.
If you have never been there, Panama is shaped a bit like a crescent moon on its side. It is actually situated on an east-west axis, not north-south as many people expect. To continue flying north, Arena will actually have to fly west for a bit.
Let's see if she continues flying up the coastline or does a short-cut across the Pacific to the Pearl Islands.
Linda has left the coastal terrace and moved up into the high country of the Andes. She roosted on a ridgeline above a river valley last night. If you have Google Earth, zoom in to this area and you will see why she is there. It is covered with high altitude lakes and ponds. This is very open country and is ideal habitat for peregrines to hunt. These abundant water sources support high populations of prey species. It is likely that some are migrating north with the falcons. Click on some the blue circle icons to see photographs of this remarkable area.
The transmitters are confirming that the high country or Puna area of Peru seems to be quite important for migrating peregrines.
Seven has returned to the coastal route and is moving north at an accelerated rate. He is near Ecuador and should arrive there today.
Subscribe to:
Posts (Atom)
