Blue-Gray Gnatcatcher

Polioptila caerulea

Blue-Gray Gnatcatcher - Male
Blue-Gray Gnatcatcher - Male. Ed Schneider

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, but birders who are experienced with birding by ear may hear these birds' distinct song and use those auditory clues to spot the birds.

Common Name: Blue-Gray Gnatcatcher, Little Mockingbird

Scientific Name: Polioptila caerulea

Scientific Family: Polioptilidae (formerly Sylviidae)

Appearance:

  • Bill: Thin, black or gray-black, relatively long for the bird size
  • Size: 4.25-4.5 inches long with 6-6.5-inch wingspan, long tail, long legs, short neck
  • Colors: White, black, blue-gray, gray
  • Markings: Dimorphic species. Males 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. 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.

    Species is polytypic.

Foods: Insects, larvae, spiders, caterpillars (See: Insectivorous)

Habitat and Migration:

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.

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 distribution, however, they are generally absent from the Great Plains region where there is no suitable woodland.

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.

Vocalizations:

These are noisy birds 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 warblers are also part of these birds' vocabulary. When males are fighting, bill snaps may also be heard.

Behavior:

These are active, energetic birds that are usually solitary or found in pairs. 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.

While small insects are immediately swallowed, blue-gray gnatcatchers may beat larger insects against a branch and pluck their wings off before eating them. Males can be particularly aggressive and will chase larger birds away from good feeding areas or nesting territory.

Reproduction:

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, lichen 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.

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 altricial young hatch, both parents continue to care for the chicks for an additional 10-12 days until they are ready to leave the nest.

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

Attracting Blue-Gray Gnatcatchers:

These birds are not common in backyards and do not typically visit bird feeders, but providing bird-friendly landscaping can help attract them, particularly if insecticides are eliminated in order to preserve the gnatcatchers' preferred food source.

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.

Similar Birds:

  • Black-Tailed Gnatcatcher (Polioptila melanura)
  • California Gnatcatcher (Polioptila californica)
  • Black-Capped Gnatcatcher (Polioptila nigriceps)
  • White-Lored Gnatcatcher (Polioptila albiloris)
  • Bushtit (Psaltriparus minimus)
  • Plumbeous Vireo (Vireo plumbeus)

Photo – Blue-Gray Gnatcatcher – Male © Ed Schneider
Photo – Blue-Gray Gnatcatcher – Female © Putneypics