May is an exciting time to visit our local woodlands. Birdsong fills the air as our returning neotropical migrants exuberantly lay claim to their breeding territories. (Neotropical migrants are those that migrate south to spend the winter in Central and South America, and come north to breed. It is interesting to note that a majority of “our” bird species spends more of their lives in the tropics than they do here on their breeding grounds.)
The Scarlet Tanager (Piranga olivacea) has recently returned from the tropical forests of Colombia, Peru, and Bolivia. The breathtaking male is a glorious scarlet, with black wings and tail. You may be lucky enough to observe a male performing his courtship display as he spreads his wings and hops about on a branch below a prospective mate, showing off his brilliant back. But don’t expect the female to stand out in a crowd. Her drab olive back and yellow undersides help to camouflage her while nesting and feeding among the leafy branches of this woodland habitat.
The male Scarlet Tanager will perch high in the treetops to belt out his song – a raspy rendition of the American Robin’s song. Jeeyeet, jeeay, jeeoo, jeeyeer is tirelessly repeated, over and over. The female will sing, but more softly. Both also give a short call that is best described as chip-BURR. Once you learn to recognize this distinctive call, a leisurely walk in the woods may quickly become a ‘find the tanager’ quest.
The female Scarlet Tanager will build a nest of twigs, rootlets, and grasses toward the tip of a horizontal branch 10 to 75 feet high in a tree. Oak trees in mature forests are preferred and most nests are found 20 to 30 feet above the forest floor. Three to five light blue eggs with brown splotches are incubated for about two weeks by the female alone. During this time the male may bring her food. Both adults feed the nestlings a diet of insects that are gleaned from leaves and branches, or caught in midair. The tanager’s thick bill is perfect for capturing large insects, as well as for picking cherries, berries, and grapes in late summer.
In Connecticut, surveys have found that Scarlet Tanagers require forests of at least 30 acres in which to breed, and are generally absent from urban and overdeveloped suburban areas. Their populations continue to decline in the Northeast, due in part to Brown-headed Cowbirds. Though Scarlet Tanagers recognize parasitic Brown-headed Cowbirds as a threat, the Cowbird females are frequently successful in laying their eggs in tanager nests. The larger Cowbird nestlings outcompete the tanager nestlings for food and are often the only survivors when it is time to fledge. Cowbird parasitism is a direct result of forest fragmentation; as a forest diminishes in size, less “deep forest” nesting area remains and more “edge” is created. Cowbirds will enter a forest from its edge, but are not found within deep forest tracts.
Feeling the need for a touch of the tropics? Take yourself to the deep woods and you may be rewarded with a flash of a Scarlet Tanager.
[Audubon’s Climate Report lists Scarlet Tanagers as Climate Threatened.]