A gray streak bounds around the branches of a tree. A flick of the tail, a flash of white, and a wheezy call are the clues needed to identify this lively bird. This energetic puffball is recognized by birders as the Blue-gray Gnatcatcher (Polioptila caerulea). Found across nearly three-quarters of the United States, many bird watchers are familiar with the hyperactive gnatcatcher.
The Blue-gray Gnatcatcher, a member of the family Polioptilidae, is one of four gnatcatcher species in the US. Weighing only a few grams, this bird is scarcely larger than a hummingbird. They can be identified by their gray, white, and black plumage. The head and back are a cool, blue-gray, which fades into a white belly. The gnatcatcher also has a small bill and complete, white eyering. One of the most recognizable features is the black tail outlined by stark white outer retices (tail feathers). This color scheme is rather similar to the much larger Northern Mockingbird (Mimus polyglottos). Because the two species look so similar, the Blue-gray Gnatcatcher is sometimes referred to as “Little Mockingbird.” Breeding males sport additional markings. Their distinct black eyebrows lend them a serious air, which is amusing given the gnatcatcher’s ebullient personality.
In the East, gnatcatchers can be found bouncing around trees and shrubs in forests and edges. They seem to move constantly, hardly giving birdwatchers a chance to focus their binoculars. With tails held perkily upwards, these birds frequently can be seen snacking on insects. Despite their name, gnats actually do not make up a large part of their diet. Instead, they hunt for a variety of other insects. The white outer tail feathers are flashed while foraging, which flushes bugs out of hiding. This strategy is seen in other birds as well. The Northern Mockingbird flaunts its white wing patches for the same purpose – scaring up a nutritious insect meal.
When not foraging, they might be busy collecting nesting materials. Keep an eye out for deep-cupped nests made primarily of plant matter. The outside is garnished in lichens for camouflage and wrapped with spider webs or silk threads. The gnatcatcher is a common breeder across most of the country. In fact, its range has been expanding northward across the United States. One estimate places total range expansion at an astounding 200 miles north over just a couple decades. This change corresponds with the average increase in global temperature. Such a small bird is susceptible to many dangers, which can make nesting a difficult endeavor. To save time and energy, Blue-gray Gnatcatcher parents recycle material from previous nests for reuse in successive attempts. They can build (or rebuild, rather) up to seven nests in a single breeding season!
Their miniature size and endless movement can make them tricky to spot. It is often easier to locate them by their wheezy calls. They are capable of a variety of short utterances, all of which have a distinct raspy quality. Songs are given mostly during the breeding season. Gnatcatchers are able to mimic sounds, and their songs are generally embellished with snippets of mimicked phrases. Territorial disputes spur songs, aggressive calls, and non-vocal sounds like bill snaps.
While several subspecies of the Blue-gray Gnatcatcher are currently recognized, the species shows little morphological variation across its range in the US. Western individuals tend to be more drab than their Eastern counterparts. Several other species resemble the Blue-gray Gnatcatcher. The California, Black-tailed, and Black-capped Gnatcatchers display slight differences in plumage and reside in restricted regions of the American Southwest. Golden- and Ruby-crowned Kinglets can be easily mistaken for gnatcatchers at first glance. They both share an incredibly exuberant behavior packed into a micro-bird body. However, range, time of year, and plumage can be used to separate gnatcatchers and kinglets. Several vireo species can also be misidentified as gnatcatchers. Range, vocalization, and behavior can clue birdwatchers into correctly identifying gnatcatchers in the field.
Charming, spunky, and indefatigable are just a few words that describe this tireless bird. They are genuinely entertaining and provide a range of intriguing behaviors – a joy for birders of any level of experience. Go out to your yard or local park and find some gnatcatchers near you!