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Black-tailed Gnatcatcher

Polioptila melanura ORDER: PASSERIFORMES FAMILY: POLIOPTILIDAE

IUCN Conservation Status: Least Concern

Black-tailed Gnatcatcher Photo

Black-tailed Gnatcatchers are tiny, high-strung songbirds of the arid southwestern U.S. and northern Mexico. They’re at home in parched arroyos and thorny scrublands featuring mesquite, creosote bush, ocotillo, and cactus, where they flit among thorns and leaves to grab insects and spiders. These dark-gray birds have a neat white eyering and flashes of white on the underside of the tail. Males sport a black cap in summer. They form lasting pairs and protect the same patch of scrub year-round, scolding intruders with a scratchy zhee-zhee-zhee.

At a GlanceHelp

Measurements
Both Sexes
Length
4.3–5.1 in
11–13 cm
Wingspan
5.5–5.9 in
14–15 cm
Weight
0.2–0.2 oz
5.1–6 g
Relative Size
Larger than a Costa’s Hummingbird; smaller than a Black-throated Sparrow.
Other Names
  • Pisita colinegra, perlita colinegra (Spanish)
  • Gobemoucheron á queue noire (French)

Cool Facts

  • The Black-tailed Gnatcatcher is one of the smallest songbirds of North America, weighing about as much as one nickel.
  • Black-tailed Gnatcatchers typically occur in areas with less than 8 inches of rainfall per year, and may build nests several miles away from the nearest water source. They can get most of the water they need from the insects they eat.
  • Biologists use Black-tailed Gnatcatchers as an indicator of the health of an ecosystem, since these birds cannot survive on land dominated by human structures or non-native vegetation.
  • Some Black-tailed Gnatcatchers may stick with one mate for life, a rare strategy among songbirds. This may be a better option to them since they do not migrate, but rather spend the whole year in one small area.

Habitat


Scrub

Black-tailed Gnatcatchers live year-round in semiarid and desert thorn scrub at elevations up to 7,000 feet, often among creosote bush, salt bush, mesquite, palo verde, ocotillo, and spiny hackberry, as well as cacti such as saguaro, prickly pear, cholla, and barrel cactus. Along the lower Colorado River they may use willows as well as the invasive species tamarisk (salt cedar). They are well adapted to dry habitats and tend to be most common in areas with less than 8 inches of annual rainfall. They often live far away from streams and other bodies of water.

Food


Insects

Black-tailed Gnatcatchers eat almost entirely insects, occasionally supplemented with fruit or seeds. They forage energetically amid the thorns and leaves of shrubs, gleaning a wide variety of insects including caterpillars, walking sticks, beetles, ants, flies, bugs, grasshoppers, spiders, and insect eggs. Sometimes subdues larger prey by beating them against a branch.

Nesting

Nesting Facts
Clutch Size
3–5 eggs
Number of Broods
1-2 broods
Egg Length
4.7–5.9 in
12–15 cm
Egg Width
3.9–4.7 in
10–12 cm
Incubation Period
14–15 days
Nestling Period
9–15 days
Egg Description
Pale-white to pale-blue, variably speckled in red.
Condition at Hatching
Born naked, blind, and helpless.
Nest Description

Black-tailed Gnatcatchers build a deep, compact cup out of woody fibers, which they line with plant down, cactus wool, spiderweb, feather, or fur. Both sexes work on building the nest, a process that takes 2–4 days.

Nest Placement

Shrub

Nests are placed in forks of branches in dense thorny or leafy trees or shrubs, with plenty of vegetation overhead and around the sides to shield the nest from the hot desert sun.

Behavior


Foliage Gleaner

Black-tailed Gnatcatchers hop quickly from branch to branch as they search for insects on leaves and branchlets, with a near-constant flicking of the tail both up and down and from side to side. They move from shrub to shrub in short bursts of undulating flight. Black-tailed Gnatcatchers form monogamous pair bonds, and pairs often remain together year-round defending permanent territories. Once the breeding season has ended, they sometimes forage in loose groups and even roost together at night to stay warm. Their nests are frequently parasitized by much larger Brown-headed Cowbirds. These small birds don’t hesitate to attack larger birds (including Cactus Wrens, Curve-billed Thrashers, Canyon Towhees, Northern Mockingbirds, Pyrrhuloxias, and Brown-headed Cowbirds) that get too close to their nests. Where their range overlaps with California Gnatcatcher, the two species defend territories against each other.

Conservation

status via IUCN

Least Concern

Black-tailed Gnatcatchers are numerous, but their populations decline. Partners in Flight estimates the global breeding population at 15 million individuals, with 30% in the U.S. and 70% in Mexico. They are a U.S.-Canada Stewardship Species and rate a 10 out of 20 on the Continental Concern Score. They are not on the 2014 State of the Birds Watch List. Black-tailed Gnatcatchers show low tolerance for disturbance: they typically nest only in native vegetation, don’t occur in areas with exotic or introduced plants, and are substantially less common in urban areas than in undeveloped areas.

Credits

Range Map Help

Black-tailed Gnatcatcher Range Map
View dynamic map of eBird sightings

Migration

Resident (nonmigratory).

Backyard Tips

Black-tailed Gnatcatchers don’t visit feeders or nest in boxes. The best way to attract them to your property is by hosting native trees and shrubs, such as creosote bush, salt bush, and mesquite. You can find more planting tips for your region at the Cornell Lab's citizen science project, YardMap.

Find This Bird

Any time you’re looking for a desert bird it’s a good idea to get out early in the morning while it’s still cool and bird activity is high. You can find Black-tailed Gnatcatchers by walking through dry desert scrub. Gnatcatchers may stay hidden in the denser parts of the vegetation, but they’ll tend to stay fairly low (around eye level) and call frequently. Listen for their scratchy zhee-zhee-zhee notes to help guide you to them. Also be on the lookout for other species whose habitat they share, such as Verdin, Bewick’s Wren, and Lucy’s Warbler.

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