Some birds are always a treat to see, whether they are brilliantly colored or less common. One of my favorites is the Scarlet Tanager (Piranga olivacea). Males are the reverse in coloration from the male Red-winged Blackbird (Agelaius phoeniceus). A male Scarlet Tanager is a deep red all over except for jet-black wings. The female Scarlet Tanager is a yellowish, olive-green with grayish-black wings and tail.
Scarlet Tanagers have recently arrived from spending the winter in the mature, mountain forests of western and northern South America. To see one here, visit a large tract (minimum 70 acres, or about 28 hectares) of mature oak, oak-hickory, or mixed hardwood-hemlock forest in Connecticut. A good way to find a Scarlet Tanager is to listen for its song first and then locate it. It is usually high in the tree canopy. The song is like that of a hoarse American Robin (Turdus migratorius), so it is often called “the robin with the sore throat.” Tanagers also have a very characteristic “chick-burr” note in their call.
A Scarlet Tanager’s diet is mostly made up of insects, including ants, sawflies, dragonflies, cicadas, moths and butterflies, and their larvae. Like its southern cousin the Summer Tanager (Piranga rubra), which is better known for this behavior, the Scarlet Tanager will engage in “bee bashing.” It will hit and rake a bee or wasp against a branch to remove the stinger before eating it. When passing through our area during the spring migration, Scarlet Tanagers can often be found in large oak trees feeding on moth larvae (caterpillars). Oaks host over 400 species of these larvae, making these trees an important keystone species for wildlife.
Scarlet Tanagers will also eat native fruits, including raspberries and blackberries (Rubus spp.), shadbush (Amelanchier spp.), chokeberries (Aronia spp.), and Red Mulberries (Morus rubra).
Nests are usually on a horizontal branch high off the ground, often as high as 50 feet (about 15 meters) or more. Female tanagers lay an average of four light blue eggs. Eggs will hatch in about 10 to 14 days and the young can fly after a few weeks.
For these young birds to successfully fledge they need large tracts of forest. In smaller, fragmented forests these birds are not as successful due in part to nest brood parasitism from the Brown-headed Cowbird (Molothrus ater), which is more common in these edge habitats. Female cowbirds lay their eggs in tanager nests. The female tanager cannot distinguish the cowbird chicks from her own and will try to feed both, but the cowbirds will outcompete the tanager chicks for food. In a study in western New York State, tanager fledgling success was only 22% in patches of woods compared to 64% in an undisturbed hardwood forest.
By helping to protect large tracts of forest and wildlife corridors, you can keep these spectacular birds safe in the future. Plant a native oak tree to give them an important migration “fuel stop.”