Living Sanibel: Yellow warbler and palm warbler
Yellow warbler
This nearly solid yellow warbler can sometimes be confused with the goldfinch, but has a softer coloration that includes streaks of light brown. Like most warblers, the yellow warbler has a beautiful song that almost always begins with a rapid “sweet, sweet, I’m so sweet” followed by a dozen variations on that call. This is truly one of the most stunning of all the warblers.
Although the yellow warbler suffers from cowbird parasitism, it has evolved a fascinating countermeasure to deal with the problem. If a cowbird lays an egg in a yellow warbler’s nest, the female quickly builds a new nest over the old one, entombing the cowbird’s egg beneath it. If the cowbird lays another egg in the nest, the yellow warbler responds in kind by building yet another nest on top of the second egg. This process has been observed to create nests that are up to six layers high. Eventually the cowbird elects to choose another host bird for its egg deposit.
The yellow warbler forages in bushes, shrubs and trees. It eats mostly insects, caterpillars and fruit. It suffers from the use of herbicides and pesticides, which results in the poisoning of the bird and its chicks. As is true of all warblers, the adult is taken by kestrels and merlins, but the bird is in far more danger from habitat loss and the behavior of man than any of its other predators.
Palm warbler
A winter resident of the islands, the palm warbler in a way belies its namesake. During the summer it migrates to the distant north, far from its winter palms, breeding in the open boreal coniferous forest as far north as the open tundra. The palm warbler is the second most abundant winter warbler; only the yellow-rumped warbler can be as easily spotted. Although the palm warbler has a yellow rump as well, it is easily separated from the yellow-rumped warbler by its brown cap and yellow eyebrow and throat. It is also known to bob its little tail continuously.
Its primary diet consists of insects, beetles, caterpillars and grasshoppers, but during cold fronts when insects can prove scarce, it turns to small fruits and seeds for nourishment. The adult is sometimes taken by kestrels and merlins, but by and large it has a fairly stable population throughout Florida.
This is an excerpt from Living Sanibel – A Nature Guide to Sanibel & Captiva Islands by Charles Sobczak. The book is available at all the Island bookstores, Baileys, Jerry’s and your favorite online sites.