Ocean-hopping with CH24

Post date: Nov 19, 2013 7:22:54 PM

The migration continues, with a particularly exciting twist! Let me back up a bit...

One of the questions that interested us last summer was why we were seeing a small fraction of breeding Brown Pelicans in Texas with red pouches. This is a characteristic of the Pacific subspecies of Brown Pelicans (Pelecanus occidentalis californicus); the Atlantic subspecies, P. o. carolinensis, has a greenish-yellow pouch in breeding plumage.

P. o. californicus (Phillip Colla: oceanflight.com)

P. o. carolinensis, Shamrock Island, TX

At the annual meeting of the Waterbird Society this September, I met Clay Green, a researcher the University of Texas at Austin, who has been using satellite telemetry to track Reddish Egrets from a colony in Texas just south of where we worked last summer. While we were comparing notes, Dr. Green mentioned that a few of his tracked egrets had crossed Mexico to winter on the Pacific side. This was exciting, because it provided a potential answer to the mystery of the red pouches: if there is some level of interchange between Atlantic and Pacific pelican populations, as there is among egrets, then we might expect to see Pacific pelicans in Texas! To support this theory, however, I needed to have some evidence that Gulf pelicans might follow the same trans-Mexican migration route as reddish egrets.

This weekend, I got the confirmation I had hope for as CH24, a male from Chester Island, made the journey along the coastline and across the Mexican isthmus.

CH24 at capture (5/25/13)

Track for CH24 from 10/1 - 11/18/13

His migration took him across about 200 km (100 miles) of land at Mexico's narrowest point, from Coatzacoalcos on the Gulf to Salina Cruz on the Pacific. From there, he continued south and is currently in the La Encrucijada Biosphere Reserve, near the Mexico/Guatemala border.

Reserva Biosfera La Encrucijada, Chiapas, Mexico (Mundo Maya Official Website: http://www.mundomaya.travel/)

Although this doesn't necessarily indicate that Pacific pelicans are making the same movements, nor that some of them might stay in the Gulf to breed, it's a start!

And, as a bonus, check out this graphic showing the male/female breakdown for our 6 study sites and 3 regions:

Can't wait to see what's next...