North America has more than 50 species of warblers, but few combine brilliant color and easy viewing quite like the Yellow Warbler. In summer, the buttery yellow males sing their sweet whistled song from willows, wet thickets, and roadsides across almost all of North America.
Black-and-white Warblers act more like nuthatches than warblers, foraging for hidden insects in the bark of trees by creeping up, down, and around branches and trunks. Despite their arboreal foraging habits, they nest on the ground at the bases of trees.
Black-and-white Warblers have an extra-long hind claw and heavier legs than other wood-warblers, which help them hold onto and move around on bark.
The Swallow-tailed Kite is unmistakable in flight, with long, pointed wings and a deeply forked tail. This graceful bird rarely flaps its wings while flying but almost continuously moves its tail, sometimes to nearly 90 degrees, enabling the bird to maintain a flight path, make a sharp turn, or circle.
The Swallow-tailed Kite’s main prey are flying insects such as dragonflies and cicadas, which they capture and eat on the wing. This is such an aerial species that the birds even drink on the wing, skimming across the water’s surface like a large swallow to collect water in their beaks.
These aerial acrobats snag snakes, lizards, and even nestlings and eggs as they skim across the treetops. Unusual for a raptor, the birds eat fruit, especially on their wintering grounds.
The Swallow-tailed Kite’s U.S. breeding range formerly included at least 16 states, but is now restricted to just six states in the Southeast, with most of the population breeding in Florida. Only a small percentage of the world’s population breeds in the U.S.; while the species is still of conservation concern there, surveys show that its former population decline has stabilized, and may even be increasing slightly.
On the wintering grounds in South America the Scarlet Tanager joins mixed species foraging flocks with flycatchers, antbirds, woodcreepers, and resident tropical tanagers.
The female Scarlet Tanager sings a song similar to the male’s, but softer, shorter, and less harsh. She sings in answer to the male’s song and while she is gathering nesting material.
Red-shouldered hawks, Buteo lineatus, are probably the most common raptor in the skies above South Florida. They can be seen in and near swampy woods and even in the ‘burbs throughout the region and throughout the year.
But despite their familiarity, they remain as magnificent a sight as if seeing one for the first time.
This is mostly a bird of eastern North America, with the greatest portion of its population within the United States. It is largely nonmigratory, and Florida has a year-round population of resident red-shouldereds. But there is also a small percentage that do move to the northern U.S. and southern Canada to breed each summer and winter, and return south to Florida and Mexico. There’s also a population of red shouldered hawks that live along California’s coast, south into the Baja Peninsula of Mexico.
Around lake shores and tidal flats, especially in the wide-open spaces of the west, flocks of elegant American Avocets wade in the shallows. They often feed while leaning forward, with the tips of their bills in the water and slightly open, filtering tiny food items from just below the surface. Sometimes a flock will feed this way in unison, walking forward, swinging their heads rhythmically from side to side.
Influences outside the breeding season can matter a lot for the population health of migratory birds, but it’s tough to track what happens once species scatter across South America for the winter months. A study from The Condor: Ornithological Applications tries a new approach for determining what declining migratory grassland birds called Bobolinks eat after they head south for the winter—analyzing the carbon compounds in their plumage, which are determined by the types of plants the birds consume while growing their feathers during their winter molt.
Rice could be beneficial by providing the birds with needed calories as they prepare for their journey north, but it could also increase Bobolinks’ exposure to pesticides and threats from farmers who see them as pests. According to Renfrew and her colleagues, maintaining native grasslands, encouraging integrated pest management programs to reduce toxic pesticide applications, and compensating farmers for crops lost to feeding birds all would be helpful.
“As Bobolink populations continue to decline, Renfrew and her colleagues use state-of-the-art isotope analysis techniques to assess the Bobolink’s diet on its South American wintering grounds,” according to John McCracken of Bird Studies Canada, an expert on grassland bird conservation who was not involved with the study. “The authors conclude that rice may have negative effects on Bobolinks, owing to its relatively low nutritional quality and from exposure to insecticides.”
Bobolinks molt while in South America for the winter, and the new feathers they grow there reflect their diet. Credit: R.M. Jensen