It's September and migrating birds are showing up on Ambergris by the hundreds, some just passing through and some here for the winter. Winter seems to have started sooner this year. Bubba got a report from his birder buddy, Susan Lala at Caribbean Villas that this year El Niño is causing an earlier and colder winter up north. She has been spotting migratory avafana since the middle of August.
I quizzed Bubba last September about 'Flyways' (the paths birds use in travelling to and from) and I discovered Ambergris to be directly in the Mississippi Flyway and the Belize mainland to be in a bottleneck of the Central, Pacific and Mississippi Flyways, a unique vantage point to observe migration.
This year I asked him about 'how and why' birds migrate.
Bubba said, "Why it's easy. They fly from breeding grounds in the north, when winter threatens their food supplies, to warmer and richer sources in the south, then back again in the spring. For some, like the Black Poll Warbler, a journey of 25,000 miles.
'How' is the big mystery! Scientists don't know exactly how the migrating birds find their way over long distances, but they are discovering that birds tune into an astonishing variety of sensory cues that may be used for navigation.
Observers have long theorized that migrants use mountain ranges, rivers, and coastlines for guidance. Scientific research suggests that some birds may also set their courses by the sun, by the patterns of stars, even by the lines of force in the Earth's magnetic field, perhaps in combination with gravity.
Some birds respond to ultraviolet and polarized light and can hear low-frequency sound that travels thousands of miles. Thus upland sandpipers flying high above the Mississippi could hear surf from both the Atlantic and Pacific coasts.
How migrants process these clues is a mystery. But the incredible facts remain: the birds know where they are, and they know where they're going. This month if you keep your eyes open you should catch sight of yellow-billed cuckoos, American Redstarts or a ruby-throated hummingbird."
