Scarlet Tanager

Bright Bird: Scarlet Tanagers Favor Forest Interior

Our spring newsmagazine featured Cliff’s top ten hidden gems of birding. Here is the first of a blog series on these birds, by guest blogger Ed Pope.

The male scarlet tanager is one of the most brightly colored birds you will ever see, if you can find one. Their preferred habitat is interior forest, and they spend much of their time up in the canopy. During the breeding season, the males have bright red plumage with black wings and tails. The females are more drab, with yellow-green plumage. The winter plumage for the males is similar to the female’s.

Scarlet tanagers’ breeding range is roughly from Tennessee to southern Canada, and east of the Mississippi. They migrate as far south as Bolivia for the winter.

The interior areas of deciduous forests are the favorite habitat of scarlet tanagers. A study of nests in the state of New York showed their chances of raising at least one chick to the fledgling stage was 64% in forest interiors, but only 22% in small patches of woods. Their young are preyed upon by raccoons, squirrels and a number of other birds. Forest interior areas offer better protection from predators. An area of at least 30 forested acres is needed to maintain a breeding population.

Brown-headed cowbirds are a major problem for scarlet tanagers, which lay four eggs of their own. Cowbirds lay one of their eggs in the scarlet tanager nest, who then raise the offspring along with their chicks. The cowbird chick usually outcompetes the scarlet tanager chicks for food, and is generally the only one to survive.

Some birds have learned to deal with cowbirds by a variety of tactics:

  • Abandoning the nest, along with their own eggs, and building a new nest.
  • Physically removing the cowbird egg from the nest.
  • Burying the egg with nesting material so that it doesn’t hatch.

Unfortunately, scarlet tanagers have evolved in forest interiors while cowbirds prefer forest edges. Because of this, they have not evolved any defense against cowbirds. As forest fragmentation occurs, they become more exposed to cowbirds. The North American Breeding Bird Survey shows that the scarlet tanager population decreased 14% from 1966 to 2014. Despite this, the breeding population is still estimated to be above two million.

Scarlet tanagers feed primarily on a wide variety of insects, which they usually catch in flight. They sometimes feed on spiders, earthworms and even snails. They also eat fruit such as blackberries and mulberries, and even orange halves that humans place outside to attract orioles. They are most likely to eat fruit when insects are less plentiful.

Scarlet tanagers are songbirds, with a size between a goldfinch and a cardinal. If you’re lucky, you might hear or see one at Blossom Hollow. Enjoy the male tanager’s song in this video.

Ed Pope

Guest Blogger

Ed Pope is a retired engineer from Rolls-Royce and a CILTI member since 2002.