by by Gary Pendleton
Where is the Scarlet Tanager?
The forest interior is a shady world. But on sunny days, light breaks through the canopy of trees. In spring, dappled greens and yellows create a mosaic of bright and shady, warm and cool. In this place in early May you will hear from above a burry, rolling melody that resembles the song of a robin. The song will go on, interrupted by the same bird with a loud call that sounds like chick-brr, chick-brr. It is an emphatic call, with the accent on the first syllable. That is the scarlet tanager.
The males of the species are North America’s most brilliantly colored bird as well as loud and persistent singers, but they are not often seen. In their niche, in the tops of the trees, their movements are deliberate. The sounds they make alert you to their presence, and you will need to search and crane your neck. You should be patient.
But if you catch a glimpse, sun-struck by a shaft of light, the color contrast of not merely red but scarlet against a backdrop of cool green will shock your eyes.
Locating the tanager is not too difficult. That is, if you know their sounds and if you are in the right habitat, which is the forest interior. Chandler Robbins, a highly respected ornithologist and author, is the dean of Maryland bird scientists. In a 1989 study, Chandler and his co-authors reported that in Maryland the probability of finding a tanager increased as the size of a forest patch increased and as it became less isolated from other patches.
The study is referenced in an interesting publication: A Land Manager’s Guide to Improving Habitats for Tanagers and Other Interior Forest Dwelling Birds, published by Cornell University and available on-line at www.birds.cornell.edu. Even if you are not a land manager, it is recommended reading if you seek explanation of the ecological importance of preserving forest tracts.
You will also learn about the impact of fragmentation. Roads and other disturbances can break up large tracts of forest, making them less hospitable to birds like tanagers. One of the problems of fragmentation is that nestlings become more vulnerable to predation from feral cats and blue jays.
Another problem is the brown-headed cowbird, a brood parasite that lays eggs in the nests of smaller birds like tanagers and vireos. The young cowbirds will out-compete the smaller birds for food, reducing their survival rates. Fragmentation increases the penetration of cowbirds into forest interiors.
Scarlet tanagers represent an entire community of forest-dwelling migratory birds that shares habitat and geographic distribution. Satisfying the habitat requirements of scarlet tanagers will improve conditions for dozens of other forest dwelling bird species.