15 May, 2012

Island Crossing the Isthmus of Tehauntepec

Sorry for the tardy posts but I have been re-orienting after my return from South America.

On 11 May, Island Girl continued on her traditional route north here, the same one we have documented over the last four years.

She climbed into the mountains of southern Mexico and roosted on a forested ridge at 1,988' elevation. Her perching area was only about 260' from what looks like a main road heading for the town of San Juan Guichicovi, not far from the main highway across the Isthmus, Ruta 185.

She flew 223 km (139 miles) for the day.

If you look at her route, you can see why she follows this heading. It is a perfect curve taking her towards the Gulf Coast. If she had continued NW, she would have been commited to a Pacific coastline route.

How does she determine when to cross? Is it all instinct? Does she remember the lay of the land? She has certainly passed this way many times before. How much a part does her experience play at this point? Why is it that she knew exactly what to do while Felipe made what now looks like a fatal error in stopping his migration and remaining for an extended period at 15,000 feet?

No comments: