Of a Feather: Who is that masked warbler?

By BILL CHAISSON
By Bill Chaisson

We had only one resident warbler in my neighborhood when I was growing up. Apparently it was too urban. What passed for woodland were only relatively recently abandoned lots that were filled with monocultures of Norway maples. These trees are fast growing and, like all maples, very shallow rooted. Unlike native maple species, Acer platanoides is so greedy for water, and its canopy is so dense that little can or will grow under it. This means there were no understory trees and nothing growing on the “forest” floor except a few invasive plants tolerant of deep shade and dry conditions. This is a classic instance of a disturbed landscape that is inhospitable to native woodland birds like warblers.

The riverfront habitat tended toward early succession species, native and non-native. There was more variety there and more vertical structure to the vegetative assemblage. Old landfilled dumps took the form of peninsulas built out into the shallows of the river. These proved to be excellent stopping over places for warblers on both the spring and fall migrations up and down the Hudson River. Warblers migrate at night, so the best time to be out there looking for them was very early in the morning, when they were ravenous with hunger and paid little mind to a boy with binoculars staring at them. It was an opportunity to learn my “confusing fall warblers.”

There are railroad tracks along the river bank. The peninsulas jut out beyond them, but between the tracks and the cliffs that line the river through much of the mid-Hudson Valley there is a band of wetlands. Many of these have been filled, but thousands of acres of them have been left more or less intact albeit dotted with wrecked barges and ruins of industrial sites with forgotten purposes.

Directly in front of Beacon, where I grew up, the wetlands had been filled and only small ponds had been left along the tracks. These forlorn bodies of water were full of shopping carts, 55-gallon drums, discarded major appliances and the other detritus of a dumping ground at the edge of a city. But they were also filled with cattails and reeds (Phragmites) and lined with goldenrod and bush honeysuckle. Shopping carts etc. aside, it was good habitat for the common yellowthroat, and this is where I found the only resident warbler in my neighborhood.

Geothlypis trichas used to be the only member of its genus that ranged up into the United States; all of the other species called “yellowthroat” are found in Latin America. Recently, however, the Kentucky, mourning, and MacGillveray’s warblers have been reassigned from Oporornis to Geothlypis.

G. trichas is among the more wide-ranging warblers in the United States. It was once called the “Maryland yellowthroat” only because it was first identified in that state. It breeds from the Yukon to Newfoundland and south across the entire U.S., excepting the Great Valley of California, pieces of the Southwest and much of Texas. As with many wide-ranging bird species there are regional variants. Sibley presents only four, but up to 14 subspecies have been recognized over the years.

Arthur Cleveland Bent, writing in the early 20th century, recognized four eastern subspecies. However, there are few impediments in the eastern U.S. to a bird attracted to scrubby wetlands, and Sibley lists only one eastern subspecies in his field guide. He describes the male as “fairly dark brownish with medium extent of yellow; grayish frontal band.” The Southwestern males are the smallest and brightest subspecies, with yellow from their throats to their bellies and a bright white frontal band.

I first noticed the yellowthroat as a boy, when poking my way along the railroad tracks, I heard its voice. Its song is a loud, rhythmic “witchery, witchery, WITCHERY, which,” repeated sometimes over 100 times per hour. The species is often described as “furtive” because you hear it much more often than you see it. They favor dense undergrowth and, unlike yellow warblers (which often haunt the same territory), the yellowthroat tends to sing from a hidden perch.

Like a lot of warblers during the breeding season, when its hormones are surging, the male yellowthroat can be lured out toward the edge of the open by pishing. They may be furtive, but they are also staunch defenders of their territory, and the male will come out to face all comers. When he sees that the interloper is just a human with binoculars, he will jump from twig to twig in an aggravated manner for about 30 seconds, staring at you with apparent impatience, uttering his jip call, and then disappear back into the underbrush.

The black mask or “domino” of the male yellowthroat is distinctive. As Peterson points out the only other species it can be confused with is the Kentucky warbler, which turns out to be a relative. He also notes that the yellow-throat’s—he hyphenates the name—behavior is quite wren-like. Because of his insouciant personality, his mask does not make you think of the Lone Ranger, but Zorro.

The female yellowthroat lacks the black mask and frontal band above it. Her throat is a paler yellow and her back and sides tend to be browner than the male’s. And while the brown of the males tends to have an olivaceous wash, this is reduced or absent in the female. The immature birds seen in late summer and fall are even more subdued, sometimes lacking even a trace of yellow on the throat.

According to Bent, “The nest is a rather large, bulky structure composed of dead grass, weed stems, dead leaves, grape vine bark, dead ferns, etc. all loosely put together. The lining consists of fine grasses, tendrils, delicate fibers of bark, and often a quantity of hair.”

Look for it within a few feet or inches from the ground or water, but always in the middle of an impenetrable tangle.

Bill Chaisson has been a birdwatcher from the age of 10. He is a former managing editor of the Eagle Times and now lives and works in the town of Wilmot. Contact him at [email protected].