Pine Warbler

Pine Warbler
Photo: Inge Curtis

These cute warblers are resident in this region year-round but seen more often in fall and winter when more northerly breeders join their brethren in this warmer clime. As they feed on seeds instead of insects, they don’t need to migrate further for wintering in the sub-tropics.

Tracking Whimbrel

Whimbrel on the beach
Photo: Inge Curtis

An elegant shorebird with a lovely piping call of the wild. After they leave their breeding grounds in the tundra,  Whimbrels stop to feed on fiddler crabs in the mudflats of the Eastern Shore of Virginia. By October, they leave here for wintering grounds in the Caribbean basin and South America. The journey is thought to be along the Western Atlantic Flyway with other shorebirds, including Red Knot.

Dominion Energy is planning to build wind turbines about 23 nautical miles off our shores as a major contribution to reducing greenhouse gas emissions. To study the risks for migratory birds, the Nature Conservancy and the Center for Conservation Biology have attached GPS transmitters and altimeters to 15 whimbrels this year for mapping their route(s) on fall and spring migrations. Planners will be relieved if the birds avoid the wind farm and fly higher than the towering turbines.    

Scarlet Tanager

Scarlet Tanager
Photo: Inge Curtis

Spotting a Scarlet Tanager in the upper story of an Eastern Forest transports me to the tropics. And it is a tropical forest dweller in our winter months.

Our Northern Cardinal is almost as rosy and House Finches a bit less. Their red plumage is thought to come from carotenoids obtained in the diet (originally beta-carotene, the abundant precursor in plants—think carrots). Since tanagers are mostly insectivorous and insects have a lot of carotenoids, there is an easy explanation for why tanagers are bright red, except for an awkward fact.

While cardinals remain much the same color the year round, male Scarlet Tanagers are much less rouge when they go south, although they still have black wings and a black tail. They look like female tanagers, olive-yellow. Their diet is still based on insects in the tropics, so that is unlikely to account for the change. Since their testosterone levels plummet to female levels after the breeding season, does that suppress gene expression in the liver where carotenoids are converted to pigments (by p450 cytochrome enzymes)? Please enlighten me, readers.

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