Blue-Gray Gnatcatcher

Polioptila caerulea

Blue-Gray Gnatcatcher - Male

Ed Schneider/Flickr/Used With Permission

The most widespread gnatcatcher in North America, the blue-gray gnatcatcher is an energetic bird that is often overlooked because it stays high in tree foliage. Birders who are experienced with birding by ear may hear these birds' distinct song and use those auditory clues to spot the birds in order to see their more distinct characteristics, including their tail flicking postures and aggressive foraging. Blue-gray gnatcatchers are classified in the bird family Polioptilidae along with more than a dozen other gnatcatcher and gnatwren species, and were formerly considered members of the Sylviidae family with babblers and parrotbills. There are many more interesting facts birders can discover about these exciting birds, including how to bring them right to the backyard.

Fast Facts

  • Scientific Name: Polioptila caerulea
  • Common Name: Blue-Gray Gnatcatcher, Blue-Grey Gnatcatcher, Little Mockingbird
  • Lifespan: 3-4 years
  • Size: 4.25-4.5 inches
  • Weight: 5-7 grams
  • Wingspan: 6-6.5 inches
  • Conservation Status: Least concern

Blue-Gray Gnatcatcher Identification

These male gnatcatchers have soft blue-gray upperparts and the head shows a bright white eye ring and a distinct black eyebrow that meets at the top of the bill to give the bird a menacing glare. The wings are darker, and the underparts are paler whitish-gray. The black tail has white outer tail feathers. Females are similar but lack the black eyebrow and are overall paler than males, with plumage that is more gray than blue. Juveniles are similar to adult females but molt into their adult plumage in late summer or early fall the same year they hatch.

These noisy birds are more often heard than seen, and their raspy "speee" notes are strung together with 3-4 syllables making a distinct song, though different syllables may vary in pitch. The calls have a nasal quality, and some harsh warbles are also part of these birds' vocabulary. When males are fighting, bill snaps may also be heard.

Blue-Gray Gnatcatcher Habitat and Distribution

These gnatcatchers prefer open wooded habitats ranging from swamps and riparian thickets in the eastern part of their range to drier chaparral and pinyon-juniper forests in the west. Oak forests and shrubby areas are also suitable for blue-gray gnatcatchers.

These birds are year-round residents in southern California and along the Baja peninsula, as well as throughout much of Mexico as far south as the Yucatan peninsula. Their year-round range also stretches along the Gulf Coast and into Florida, as well as north along the Atlantic Coast as far as North Carolina. Blue-gray gnatcatchers are also found year-round in the Bahamas.

Migration Pattern

In summer, these small birds extend their breeding range further north and are found throughout California, Nevada, and Utah in the west, and in the east they are seen in eastern and central Texas as well as throughout Oklahoma, eastern Kansas, Iowa, southern Wisconsin, and throughout the eastern United States. Despite their extensive summer range, however, they are generally absent from the Great Plains region where there is no suitable woodland for safe nesting.

In winter, these birds migrate slightly further south and can be found in western Mexico and into Central America as far south as western Honduras. They are also seen in Cuba and other parts of the Caribbean.

Behavior

These are active, energetic birds that are usually solitary or found in pairs. Males can be particularly aggressive and will chase larger birds away from good feeding areas or nesting territory. Blue-gray gnatcatchers are generally arboreal, preferring to stay higher in the tree canopy and flitting from branch to branch, very rarely coming down low or landing on the ground.

Diet and Feeding

Blue-gray gnatcatchers are primarily insectivorous, feeding on a wide variety of bugs. While the exact prey they catch will depend on what insects are most abundant nearby, they often prey on larvae, spiders, and caterpillars, as well as their namesake gnats. They can be acrobatic as they move around in the upper foliage of trees gleaning and hawking for insects, and they often flick their tails open and closed or from side to side as they hunt. While small insects are immediately swallowed, blue-gray gnatcatchers may beat larger insects against a branch and pluck the bugs' wings off before eating them.

Nesting

These are monogamous birds and both males and females work together to build a cup-shaped nest from 3-25 feet high in a tree, though some nests can be found much higher. The nest is made from a variety of soft, fine material, including feathers, moss, lichens, and plant fibers, and it is bound together with spider silk. Blue-gray gnatcatchers may begin constructing several nests before starting to lay eggs, and nesting material may be recycled between nests.

These birds are susceptible to brood parasitism from brown-headed cowbirds. Young gnatcatchers cannot easily compete if the much larger brown-headed cowbird fledgling takes over the nest.

Eggs and Young

The oval-shaped eggs are either pale blue or bluish-white and are speckled with dark spots. There are 3-5 eggs in each brood, and only one brood is raised each year, though a second brood may be raised in southern populations with longer breeding seasons. Both parents share incubation duties for 11-13 days, and after the chicks hatch, both parents continue to care for the young birds for an additional 10-12 days until they are ready to leave the nest.

Blue-Gray Gnatcatcher Conservation

Blue-gray gnatcatchers are not considered threatened or endangered, and in fact their range is expanding as climate change warms the northern parts of their range and makes more areas suitable for breeding. These birds will easily abandon their nests if disturbed, however, so it is important to protect nesting areas from interference or local populations can suffer.

Tips for Backyard Birders

These birds are not common in yards and do not typically visit bird feeders, but providing bird-friendly landscaping can help attract them. Mature, deciduous trees are essential for blue-gray gnatcatchers to forage, and shrubby brush areas are also useful habitat. Insecticides should be eliminated in order to preserve the gnatcatchers' preferred food source, and spiderwebs can be left intact to provide nesting material.

How to Find This Bird

Because these are small birds that like to stay high in trees, they can be more challenging to find in the field. Visiting the appropriate habitat and watching for movement in the canopy while listening for the birds' distinctive voices is the best way to find blue-gray gnatcatchers. They can be active at any time of day, but are generally easier to find in the later afternoon when insects are more active and easier to hunt.

Explore More Species in This Family

Gnatcatchers are all interesting birds, and birders who want to learn more about them should read up similar species such the bushtit. Be sure to visit all our bird species profiles to get more facts and information about your favorite birds!