The black-tailed gnatcatcher (''Polioptila melanura'') is a small, insectivorous bird which ranges throughout the Sonoran and

Chihuahuan Desert The Chihuahuan Desert ( es, Desierto de Chihuahua, ) is a desert ecoregion designation covering parts of northern Mexico and the southwestern United States. It occupies much of far West Texas, the middle to lower Rio Grande Valley and the lo ...

s of the southwestern United States and northern

Mexico Mexico (Spanish: México), officially the United Mexican States, is a country in the southern portion of North America. It is bordered to the north by the United States; to the south and west by the Pacific Ocean; to the southeast by Guatema ...

. It is nonmigratory and found in arid desert areas year-round.

Taxonomy

The black-tailed gnatcatcher was described by American ornithologist

George Newbold Lawrence George Newbold Lawrence (October 20, 1806 – January 17, 1895) was an American businessman and amateur ornithologist. Early life Lawrence was born in the city of New York on October 20, 1806. From his youth, Lawrence was a lover of birds and s ...

in 1857. Meaning 'black-tailed', its specific name is derived from the

Ancient Greek Ancient Greek includes the forms of the Greek language used in ancient Greece and the ancient world from around 1500 BC to 300 BC. It is often roughly divided into the following periods: Mycenaean Greek (), Dark Ages (), the Archaic p ...

''melano-'' 'black' and ''oura'' 'tail'.

Description

The black-tailed gnatcatcher reaches about 4.5 to 5 inches in length, much of it taken up by a long black tail lined with white outer

feathers Feathers are epidermal growths that form a distinctive outer covering, or plumage, on both avian (bird) and some non-avian dinosaurs and other archosaurs. They are the most complex integumentary structures found in vertebrates and a premier ...

. The body is blue-grey, with white underparts, and while it is similar to the

blue-grey gnatcatcher The blue-gray gnatcatcher or blue-grey gnatcatcher (''Polioptila caerulea'') is a very small songbird native to North America. Description It is in length, 6.3 in (16 cm) in wingspan, and weighing only . Adult males are blue-gray on the upperpa ...

, the two birds are differentiated by the amount of black in the tail feathers. The male has a black cap during the summer that extends to the eyes. Females and winter males, lacking the black cap, are difficult to distinguish from the blue-grey gnatcatcher. The best way to tell the two apart is the tail; that of the blue-grey is mostly white when viewed from below, and the black-tailed is predominantly black underneath. Like other gnatcatchers, it may give harsh, scolding calls while foraging for small insects and spiders in desert shrubs.

Behaviour

Black-tailed gnatcatchers live in pairs all year, defending their territory and foraging in trees and low shrubs for a wide variety of small insects and some spiders. Unlike the blue-grey gnatcatcher, the black-tailed variety rarely catches insects in midair.

Breeding

The

nest A nest is a structure built for certain animals to hold eggs or young. Although nests are most closely associated with birds, members of all classes of vertebrates and some invertebrates construct nests. They may be composed of organic materi ...

is an open-cup, built by both sexes, and is typically found in low shrubs less than five feet off the ground. If available at the nesting site, desert mistletoe, ''

Phoradendron californicum ''Phoradendron californicum'', the desert mistletoe or mesquite mistletoe, is a hemiparasitic plant native to southern California, Nevada, Arizona, Sonora, Sinaloa and Baja California. It can be found in the Mojave and Sonoran Deserts at elev ...

'', is often used as the substrate for the nest, which provides nice concealment. It is constructed of a variety of materials including

weed A weed is a plant considered undesirable in a particular situation, "a plant in the wrong place", or a plant growing where it is not wanted.Harlan, J. R., & deWet, J. M. (1965). Some thoughts about weeds. ''Economic botany'', ''19''(1), 16-24. ...

grass Poaceae () or Gramineae () is a large and nearly ubiquitous family of monocotyledonous flowering plants commonly known as grasses. It includes the cereal grasses, bamboos and the grasses of natural grassland and species cultivated in lawns a ...

, strips of bark,

spider Spiders ( order Araneae) are air-breathing arthropods that have eight legs, chelicerae with fangs generally able to inject venom, and spinnerets that extrude silk. They are the largest order of arachnids and rank seventh in total species ...

webs and plant fibers. It is lined with finer, softer matter. Three to five bluish-white

eggs Humans and human ancestors have scavenged and eaten animal eggs for millions of years. Humans in Southeast Asia had domesticated chickens and harvested their eggs for food by 1,500 BCE. The most widely consumed eggs are those of fowl, especial ...

with red-brown dots are incubated by both parents and take 14 days to hatch. The young are fed by both parents, and leave the nest 10 to 15 days after hatching. Even though

cowbirds Cowbirds are birds belonging to the genus ''Molothrus'' in the family Icteridae. They are of New World origin, and are obligate brood parasites, laying their eggs in the nests of other species. The genus was introduced by English naturalist Will ...

often lay eggs in this species' nests, and the pair end up raising cowbird young, the black-tailed gnatcatcher population seems to be holding up well.

References

External links

Black-tailed Gnatcatcher

Black-tailed Gnatcatcher
at birdfriends.com

VIREO ttp://vireo.acnatsci.org/species_image.php?species=Polioptila+melanura Photo-High Res--(Close-up) {{Taxonbar, from=Q901899 black-tailed gnatcatcher Endemic birds of Southwestern North America Birds of Mexico Fauna of the Sonoran Desert Fauna of the Chihuahuan Desert Fauna of the Lower Colorado River Valley Birds of the Rio Grande valleys Native birds of the Southwestern United States black-tailed gnatcatcher black-tailed gnatcatcher