Friday, December 30, 2011

Wintertime is great for observing Florida 'snowbirds'

We have two sorts of "snowbirds" on Florida beaches - human and avian.

Many come long distances to enjoy the mild oceanic weather of the low latitudes during winter. Some of the birds breed in northern Canada so the contrast between their summer and winter habitats is considerable.

It is fascinating to compare the different modes of feeding employed by various shorebirds. It can also be difficult for the uninitiated to distinguish among the species, some of which are confusingly similar. I recommend learning a few of the more common types of gulls, terns, egrets/herons, plovers and sandpipers to enhance your knowledge of beach ecology.

One of the most treasured birds is the common loon, which is not strictly speaking a beach bird, but it will feed just adjacent to the beach. This loon was swimming a few feet off the beach at Don Pedro Island, allowing it to trap small fish up against the sand.

Loons breed in northern freshwater lakes and have a marvelous call that has been used in movie sound tracks (notably "On Golden Pond") for years as a call of the wild. It is a special treat to see them in their winter saltwater habitat although their non-breeding plumage is drab compared with their summer finery. You will notice most of the birds are quite inconspicuous in winter to better blend in with the surroundings.

On the beach, especially in muddy areas, you will often see the dunlin, a mid-sized sandpiper with a long down-turned bill. It goes around probing the sediment for small invertebrates.

In comparison the red knot is slightly larger and has a shorter straight bill, which is used to pick food off the surface.

These two birds breed in the Arctic and illustrate how body size and bill length define the life styles of shorebirds. Red knots are famous for staging with millions of other shorebirds in Delaware Bay to fatten up on the eggs of horseshoe crabs before they fly north.

The plovers are a an interesting group of small- to medium-sized birds with short bills and a distinctive upright profile that picks up food from the surface. The largest is the black-bellied plover (only black in summer), which breeds in the Arctic north of Hudson Bay.

Two smaller plovers, the snowy and Wilson's, breed in Florida, including right here on Gasparilla Island.

Some of our wintering snowy plovers have been banded and found to breed on beaches in the Florida Panhandle. Many Wilson's plovers breed in our area. It is intriguing that the Wilson's has a larger bill than the snowy, apparently the better to catch and eat small ghost crabs.

One should not neglect to look overhead to observe birds such as gulls, terns and some exciting tropical visitors such as the magnificent frigate bird soaring overhead. Frigate birds are the ultimate flying machine with the longest wings relative to body mass of any bird.

They are parasites on other fish-eating birds and virtually never land on the surface. They breed in the Caribbean and the males have a bizarre red pouch under the throat, which is inflated and used to attract females.

To illustrate the amazing design of the frigate bird, I took a photo in the Yucatan of a rarely seen perched adult female. This illustrates the huge wings and giant hooked beak, which is used to pick up food from the surface without landing, or to attack other birds to steal their food.

The next time you go to the beach, look around to see what birds are there and you will begin to learn the major categories and species. It will enrich your experience to know a bit more about beach ecology and allow you to compare beaches at different times and observe changes. There is so much more to beaches than just sun, sand and waves.

Source: http://www.bocagrandetalk.com/page/content.detail/id/516375.html

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