20 April, 2014

Heart of the Atacama Desert

Island Girl flew north for 344 km (214 miles) on Friday, her third day of this migration. She is flying hard and has covered 623 miles so far, an average of 211 miles per day. Serious migration going on here.

She passed Copiapo, Huasco and Caldera, and eventually trended west until she arrived on the Pacific coastline near Chanaral.

Island Girl is now back in the heart of the Atacama Desert, an area she knows well after successfully navigating it so many times before. No trees, no water, no vegetation, very few birds.

I suspect the reason she came back down to the coastline was to hunt shorebirds or seabirds as there is so little to feed on out in the desert. It takes lots of energy to migrate.

Yesterday, one of her fans asked what she eats out there. The quick answer is very little. I have followed this route many times, driving from La Serena all the way north as far as Ecuador and I can report that you can literally drive parts of this desert for days without seeing a plant or a bird.

In fact, your question remains one of the mysteries of peregrine migration in the Atacama region. We know that Island Girl will stop off in the river valleys where there is lots of water/agriculture and abundant bird life. She definitely likes those areas for obvious reasons.

We also know that she often visits or detours to the coast, presumably to hunt there too. Lots of birds live along the edge of the ocean of course.

But when she travels inland through that dry, desolate place, there is no apparent food available. I have discussed this issue with my friend, Chilean peregrine expert Christian Gonzalez, many times and we are both still wondering what the answer might be.

Best guess so far, based on some scant evidence, is that she eats large insects taken high in the air over the desert. We know that peregrines eat insects fairly regularly. For example, my friend, Kate Davis, reports a nesting pair of peregrines taking those famous, huge, orange salmon flies over a river during the breeding season in Montana. I have observed an adult peregrine eat a huge moth in Salinas, Ecuador. Others report this behavior as well.

Obviously we need more observations to answer your question definitively.

Good question by the way.

But back to Island Girl...

On Friday afternoon, she left the coast again and flew back inland to sleep, spending the night on the shoulder of a small, rocky ridge above a broad, open plain of dirt and rock that is so typical of the Atacama..

The site was NE of Chanaral at 1,972' elevation and 6 km (3.8miles) west of the Pan Am Highway. Once again, she could see, if not hear, the traffic all night.

The Pacific Ocean was 12 km (7.5 miles) to her west. So she was not far from the extraordinarily beautiful Pan de Azucar National Park.

1 comment:

Susan Miller said...

Bud, many thanks for your response regarding what Island Girl may be eating as she flies through such barren terrain. Several of us (all over the U.S.) have been watching her journey and were concerned. Obviously she knows what she is doing, but still, one wonders. Her migration seems so energy-intensive, yet the migration route doesn't seem to offer much in the way of obvious sustenance.