Each fall millions of Nearctic-Neotropical migratory songbirds cross the Gulf of Mexico, a geographic barrier that requires non-stop flights of up to 1400 km to cross. We know that many birds are able to successfully accomplish this demanding task, because enormous numbers of migratory birds appear along the southern coasts of the gulf, e.g., Yucatan Peninsula and Veracruz, each fall. Yet, we know little about the basic aspects of these flights. For example, how long does it take a bird to cross the gulf? Where do birds depart from and arrive at? Is departure direction a good predictor of arrival location; in other words, are birds able to compensate for wind drift over the gulf? How much variation exists among species or among individuals within a species?

Many scientists and bird enthusiasts believe that most birds departing from the southeastern United States are headed to the Yucatan Peninsula, since migration through the peninsula offers the most direct route to many species' wintering areas. However, the proportion of birds departing the southeastern U.S. that use the peninsula and their specific migration routes are unknown. Manual tracking of three species in Alabama during fall migration shows a wide range of departure directions from their initial capture site, suggesting that birds use a variety of strategies and routes for crossing the gulf (Figures 1 and 2).

Figure 5. Picture of microphone attached to our telemetry tower at Holbox, Balam Flora and Fauna Protected Area, Quintana Roo.

Figure 11. Location of seven automated radio-telemetry receiving locations along the northern coast of the Yucatan Peninsula.

Towers were placed at the following locations in the Yucatan Peninsula (West to East)

• Sisal, Yucatan (Coox Mole plastic recycling collection center)
• Chicxulub, Yucatan (Montes Molina Residence)
• Dzilam de Bravo, Yucatan (Sayachuleb Visitor's Center)
• Rio Lagartos Field Station, Ria Lagartos Biosphere Reserve, Yucatan
• El Cuyo Field Station, Ria Lagartos Biosphere Reserve, Yucatan
• Holbox, Balam Flora and Fauna Protected Area, Quintana Roo
• Isla Contoy, Contoy Island National Park, Quintana Roo

Receiving tower on top of the Rio Lagartos Field Station, Ria Lagartos Biosphere Reserve, Yucatan.

OUR FIRST BIRD DETECTED IN YUCATAN
 
This Swainson's Thrush (transmitter frequency 164.523) was radio-tagged in Alabama on September 29, 2009 and departed that same day at about 18:30 hrs. The bird's departure direction was S-SE. It was detected the following day, September 30, at approximately 15:40 hrs by three receiving towers in the eastern Yucatan Peninsula (Figure 12), taking about 21 hrs to complete its flight across the gulf. Wind direction was toward the S-SE at the time of departure, and the bird had large fat deposits upon its capture earlier on the morning of the 29th.