Wednesday, June 12, 2013

Yellow Warblers

Many warblers have at least some yellow, but I imagine if there's one that deserves the name of the color, it's the Yellow Warbler (Setophaga petechia).

The spring migration has come and gone, and now we have to be content with the summer residents that remain. Robins seem to be everywhere, and unfortunately so are the starlings and grackles. High in the tree tops, you might hear an oriole; they seem to prefer big cottonwoods here. If you have orioles near you, what trees do they prefer?  Orioles can be relatively common, but seldom do we get a good look at the male's flashy orange and black.

male Yellow Warbler at the Allegany Nature Pilgrimage (southwestern New York,
always the first weekend after Memorial Day) during a bird-banding demonstration

Another colorful songster, though relatively common, is likely to be overlooked unless you’re in the habit of scanning shrubby wetlands and thickets while listening for its "sweet, sweet, sweeter than sweet" song. Check the tops of shrubs and dwarf willows for a bright but tiny spot of yellow. With binoculars, look for rusty-red streaking on the breast. This is the male Yellow Warbler, one of 51 North American species of wood warblers – many of which are now uncommon or quickly pass through on their way north. The Yellow Warbler on the other hand is relatively common and a widespread nester from coast to coast across the northern 2/3rds of the U.S., Alaska and most of Canada with breeding populations extending down through coastal California and central Mexico. (If you're submitting an eBird report, you can use the "Add Details" button, and then the "Breeding Code" button to record any breeding behavior you observe or hear.)

female Yellow Warbler at Montezuma National Wildlife Refuge, NY

Warblers are small birds, generally four to five inches long, with slender, straight-pointed bills used like tweezers to collect insects. Warblers are very active and it’s hard to get a good look at any of them. Most prefer woodlands in various stages of growth from scrub to mature forest and for this reason they are referred to as wood warblers. Within these habitats, some warblers stay in the treetops (giving birders "warbler neck"), some hide on the ground and the majority travel in-between. Yellow Warblers are somewhat unusual in preferring more open settings. Willow thickets and isolated shrubs in cattail marshes seem more to their liking, but any thicket will do in a pinch.

male Yellow Warbler checking its reflection for a rival in our camper window

The Yellow Warbler is a common summer resident that begins returning at the end of April. The remainder trickles in throughout May. Aptly named, they are yellow on the head and underneath, olive-yellow on the back, and a mix of olive and yellow on the wings. Males are brighter with reddish streaks on the breast. The more aggressive and dominant males have darker streaks. Females are duller with faint rusty streaks on the sides. If you get a close view, look for yellow tail spots that are usually missed.

Brown-headed Cowbird egg in Yellow Warbler nest (Bradford County, PA)

The Yellow Warbler is one of the species most frequently parasitized by cowbirds, but they have developed a defensive strategy against the blackbirds. After a cowbird egg is deposited, the Yellow Warbler builds a new nest on top of the old and lays a new batch of their own eggs. If the cowbird returns, the warbler repeats the process. The record is a six-story nest (although there is an unconfirmed report of a 10-story nest near Cayuga Lake, NY, in 1923).

As a species, the Yellow Warbler is perhaps the most widespread of the warblers, but there are three distinct groups with four subspecies. Together they span the continent and range from the Arctic down through Mexico and the Caribbean to the northern reaches of South America. You can find an interactive range map on eBird.
pair of Yellow Warblers at Montezuma National Wildlife Refuge, NY

On their territories, Yellow Warblers sing two types of songs with a number of individual variations. One song type is used to attract a mate, while the other is used to defend territories against other males. With wetlands being a limited resource, there is intense competition for prime nesting space. After mating, recognition of individuals becomes important, so minor variations in songs become important. You can find more information along with a static range map and recordings of Yellow Warbler songs on All About Birds.

Yellow Warblers have only one brood per year and as soon as the young are independent, the species begins its southward migration. They are one of the earliest summer nesters to leave. Some are gone by the end of July and (almost) all have left by the time goldenrod is in full bloom.

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Donna said...

I see these birds gathering nesting materials in my wildlife gardens and meadow as they are nesting behind me in a forever wild area along with many birds. Those that nest on my property are tree swallows, bluebirds, robins, and chipping sparrows. I see the yellow warblers at Beaver Lake Nature Center in the bog area.

Anonymous said...

We banded a female Yellow Warbler just this past Saturday in Delevan, NY

Gustav Bodner said...

Once saw a yellow warbler AND a Lucy's warbler feeding the same cowbird chick. The chick was on a branch and got fed over 6 times by each bird in 10 minutes. (Gila River, New Mexico).