Summer’s Warblers -July 2016

by: Virginia Andrews

photography by: Jeremiah Trimble

Nantucket is a bustling place in the summer. Often overlooked beyond the human throngs, the bird world is also burgeoning with life. The tiny, secretive birds known as wood warblers are among the most beautiful.

In bright new summer plumage, flying under their own muscular power, they traveled hundreds or even thousands of miles to get here. These little feathered jewels spent the winter in Florida, the Bahamas or Central America. They depend on the island’s natural areas for food and nesting materials. Seven species now breed here. The Common Yellowthroat, American Redstart and Yellow, Black-andwhite, Prairie and Pine Warblers have made their love-nests here every summer for over 30 years, raising generations of their families.

A more recent arrival is the Northern Parula.

It wasn’t always this way. As Nantucket’s landscapes have changed over time, so has the birdlife. In the mid-20th century only the Common Yellowthroat was really common, and Yellow and Pine Warblers were known to nest, but were limited to a scant handful of pairs. American Redstarts were irregular summer residents. The rest were considered rare vagrants, sometimes seen on migration in the fall, but not known to breed here.

At the end of the 19th century Nantucket was still a barren place, open and windswept, with poor, sandy soil. There were very few trees and little brush. Over the course of the 20th century, with a less agricultural, more tourist-based economy there was less pressure on the vegetative cover, and the island grew up. With bushes and trees came new bird life.

The Common Yellowthroat, once called the “black-masked ground warbler,” was apparently always here. They are still probably the most common warbler in any brushy tangle near water, in town or out. With wetlands protected, they adapted well to suburbia. The “masked bandit,” with his bright yellow throat and breast, sings his “wichety-wichety-wichety-which” song from the top of any low shrub. In this way he claims his territory, recording the deed to his nest every morning. He is always ready to scarf down a spider or a fly, or steal a leaf-munching caterpillar. The female also has a yellow throat, but a discretely plain brown head and back, enabling her to disappear easily in the bushes. Although still common, their numbers have dropped recently, and they are considered to need monitoring.

Less abundant but even more blatantly blazing yellow, Yellow Warblers are found in treetops near water. The male sports bright orange streaks on his chest and a pert dark eye. Living on the edge, males often sing “sweetsweet-sweet I am so sweet” high above even the densest parts of downtown Nantucket. Females show the same dark eye but are slightly more greenish, and usually remain hidden while they incubate their eggs.

Another inhabitant of moist woodland, the secretive Black-and-white Warbler needs dense, undisturbed natural habitat. After a slow start, by the late 1960s their numbers began to increase. Like little mice, they creep around trees, their stippled bodies remarkably hard to separate from light and shade falling through branches. They glean bark and branches for insects to feed their hungry young.

Pine Warblers and pine trees are inseparable. Their dry sweet rattle of a song makes them easier to hear than see at first. With pine-green heads and backs, they are well-camouflaged despite the bright yellow breast of the male. Sporting white wing-bars, they are the first choice of a tricky identification puzzle. Whether gleaning caterpillars in the tops of pitch pines, or picking spiders off the ground, they are one of our more numerous summer warblers. Although not always easy to see, watching for movement out of phase with the wind reveals the bird within the cluster of needles.

In the 1940s the absence of Prairie Warblers from Nantucket, while they were relatively common on Cape Cod, was a mystery. By 1975, however, some arrived to claim a small nesting footprint. Today a few pairs nest in low shrubs near grasslands maintained by the Nantucket Conservation Foundation. Their rising burble of song can be heard on summer mornings in the central moors and sometimes in Head of the Plains.

Only a few locations support American Redstarts on Nantucket. They prefer tall trees and wetland habitat. They too are more often heard than seen. Listen for their melody among the wind-shaped trees of Squam and Wauwinet. Flashing their brightly-marked ed and black tails to scare insects out of concealment, they were once compared to a candle or a dancing torch in the forest.

The Northern Parula is the most recent arrival on the island’s list of breeding warblers. Only confirmed in 2011, it too needs the combination of low shrub and dense tree cover provided by areas like Squam Swamp. With a rainbow necklace on a yellow breast, broken white eye-ring and blue head and wings, the male is a very handsome bird. Ascending the scale, his song cascades over the top like a bottle being over-filled.

All of these warblers are neotropical migrants. They spend roughly half the year in the tropics, coming north when insect food becomes available there. While some species are of greater concern than others, all have declined more than 80 percent since the 1940s. With more habitat disappearing every day, Nantucketers can be proud to have so much land protected in conservation, supporting important birds and bird areas in our changing world. ///

Virginia Andrews writes the weekly “Island Bird Sightings” column for The Inquirer and Mirror and is a regular feature writer for Nantucket Today.

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