Things seem to be progressing nicely with the bird community in and around my meadow. The blue jays and northern cardinals are going through their “ugly duckling” phase and there are a couple of young jays that are particularly gruesome in appearance. One bird lost all of its head feathers at the same time, making it look like some strange little vulture. This hasn’t dampened their enthusiasm, however, and the energetic mob that arrives every morning at about 7 a.m. is always eager to see if I have any peanuts for them.
I’ve also noticed begun to notice increasing evidence of the great migration that is already underway. Last week I wrote about the brief appearance of a juvenile chestnut-sided warbler and this week I can report the similarly brief appearance of a female black-and-white warbler. She was the only representative of her species that I have seen all year and she was only visible for about 60 seconds. Had I not been in the right place at the right time I would never have known the bird was present. That’s the nature of birding.
The black-and-white warbler (Mniotilta varia) is another species of “wood warblers” that follows a similar pattern of migration and breeding that is exhibited by most of the neotropical migrants. In this case, the bird tends to arrive in our area in May as the main population pauses for a rest on its way north. Some birds stop when they reach the eastern half of the United States, but others continue up into the eastern half of Canada.
The most interesting variation in the general warbler pattern for the black-and-white warbler is probably its approach to nesting. This species prefers to build its nests on the ground at the base of a tree, a stump, a large rock, or along side a fallen tree. The nest is reliably cup-shaped and is built of bark, fallen leaves, dried grasses and pine needles; all typical materials found in the forests this species lives in.
Once the main foundation of the cup is complete, the female birds (who are entirely responsible for construction) will collect the softest possible materials with which to line the nest. This may include fine grasses, animal hair, and mosses. That last ingredient is so important to the species that it has been an integral component of the species’ scientific name. The genus name “Mniotilta” is a mash-up of the Greek words “mnion,” which means “moss,” and “tilo,” which means “to pluck or pull.”
During the summer months the bird is downgraded to “uncommon” and “occasional,” before once again showing a burst of activity in the second half of August and the first half of September. For that four-week window the species is described as being “common,” in Massachusetts, but it really depends on where you are. By then end of September the species will disappear. Insectivorous species like the black-and-white warbler can physically tolerate cooler temperatures, but as the insects prepare themselves for winter, the birds must flee to the warmer climes of Central and South America. These guys never experience the northern winter.
The individual that I noticed was an adult female. She may have been present and visible for a bit longer than I was aware, but her diminutive size and her distinctive coloration might have rendered her invisible for a moment. There were many chickadees, titmice and an active group of white-breasted nuthatches in the area and I was occupied with their collective antics. I suppose I have to characterize my observation of the warbler as “almost accidental.”
I have a treasured copy of “The Sibley Guide to Birds,” in my private library and the species account on page 446 mentions the fact that the black-and-white warbler often “creeps like a nuthatch.” This specific behavior is probably what allowed me to initially overlook this particular bird. I had been watching the nuthatches for so long that I didn’t realize there was another species imitating them; hiding in plain sight.
Once the bird had my full attention I was able to swing my big telephoto lens around and start taking photos. At one point the bird hung upside-down from a dead tree limb in a perfect example of its nuthatch behavior. There were many interesting photos to choose from for this week’s column, but I decided to go with the best profile shot of the collection. There can be no doubt that this bird was a black-and-white warbler. Her pure white chin and throat easily identified her as a female. Adult male would have had extensive intrusions of black feathers in this area.
The great migration is in full swing and birds are pouring out of Canada in huge numbers. As I write this column I am looking at last night’s migration map on BirdCast and the eastern half of the US is aglow with bird activity. At the height of the night’s activity there were 180 million birds in the air and one can only wonder how many of them were warblers. Get outside, even for just a little while, and you may notice a new face peeking at you from the underbrush.
Bill Danielson has been a professional writer and nature photographer for 28 years. He has worked for the National Park Service, the US Forest Service, the Nature Conservancy and the Massachusetts State Parks and he currently teaches high school biology and physics. For more information visit his website at www.speakingofnature.com, or go to Speaking of Nature on Facebook.