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Polioptila melanura
black-tailed gnatcatcher


By Hanna Coy

Kingdom: Animalia
Phylum: Chordata
Subphylum: Vertebrata
Class: Aves
Order: Passeriformes
Family: Polioptilidae
Genus: Polioptila
Species: Polioptila melanura
Members of this Species

Geographic Range

Black-Tailed Gnatcatchers are found throughout northern and central Mexico and the southwest deserts of the US. (Sibley 2000)

Biogeographic Regions
nearctic (Native )

Habitat

All gnatcatchers are found in open areas. Black-Tailed Gnatcatchers prefer arid scrublands. They are common in desert washes. (Sibley et al 2001)

Habitat Regions
temperate ; terrestrial

Terrestrial Biomes
desert or dune ; chaparral

Physical Description

Average mass
5 g
(0.18 oz)

Average length
11.4 cm
(4.49 in)

Average wingspan
14 cm
(5.51 in)

Black-Tailed Gnatcatchers are small blue-gray birds with a slender bill and tail. They are very active. The breeding male has a black cap which is not present in the basic plumage. Both males and females have a tail that is mostly black, with a small amount of white at the ends of the outer retrices. (Sibley 2000)

Other Physical Features
endothermic ; bilateral symmetry

Reproduction

It is thought that Black-tailed Gnatcatchers form monogomous pair bonds that last longer than the breeding season, but the duration of these bonds is not well known.

Mating System
monogamous

Range eggs per season
2 to 6

Range time to hatching
11 to 15 days

Range time to fledging
10 to 15 days

Average age at sexual or reproductive maturity (female)
1 years

Average age at sexual or reproductive maturity (male)
1 years

Black-Tailed Gnatcatchers form monogamous pair bonds for a given breeding season. The male defends a foraging territory. Numbers given for "number of offspring/eggs per season" are per nest. Double clutching is possible.

Key Reproductive Features
iteroparous ; seasonal breeding ; gonochoric/gonochoristic/dioecious (sexes separate); sexual ; fertilization (Internal ); oviparous

Both sexes perform nest-building, incubate, and feed during the nestling and fledgling stages. It is common for the parents to raise a second brood shortly after the first. Black-tailed Gnatcatcher chicks are altricial. (Sibley et al 2001, Smith 1967)

Parental Investment
altricial ; male parental care ; female parental care

Behavior

Black-tailed Gnatcatchers are active year-round throughout the desert regions they inhabit. They are less physically active during the summer, but they still may be observed foraging during the hottest periods in shady regions with a cooler microclimate.

They are not philopatric with respect to breeding grounds. When they are not breeding, they tend to wander throughout a region.

Black-tailed Gnatcatchers will dive-bomb another bird that approaches too close to an active nest. (Smith 1967)

Key Behaviors
flies; motile ; migratory ; territorial

Food Habits

In general, gnatcatchers feed by gleaning insects from the tips of branches. They mostly do this while perched; however, they are observed to do this while hovering near the branch tips as well. They also eat spiders. They occasionally catch insects in flight by making forays into the air from a perch. Collected specimens have been found with vegetable matter in the stomach, but this must account for only a tiny proportion of food eaten. Black-tailed Gnatcatchers obtain all of their water from the food they eat. (Sibley et al 2001, Smith 1967)

Animal Foods
insects; terrestrial non-insect arthropods

Ecosystem Roles

Black-tailed Gnatcatchers may be heavily parasitized by Cowbirds in some regions. (Smith 1967)

Economic Importance for Humans: Positive

None known.

Economic Importance for Humans: Negative

None known.

Conservation Status

IUCN Red List [Link]
Least Concern

US Migratory Bird Act [Link]
Protected

US Federal List [Link]
No special status

CITES [Link]
No special status

For More Information

Find Polioptila melanura information at

Contributors

Hanna Coy (author), University of Arizona, Jay Taylor (editor), University of Arizona.

References

Elphick, C., J. Dunning, D. Sibley. 2001. The Sibley Guide to Bird Life and Behavior. New York: Alfred A. Knopf, Inc..

Sibley, D. 2000. The Sibley Guide to Birds. New York: Alfred A. Knopf, Inc..

Smith, E. 1967. Behavioral Adaptations Related to Water Retention in the Black-tailed Gnatcatcher (*Polioptila melanura*). University of Arizona: Unpublished M.S. Thesis.

To cite this page: Coy, H. 2002. "Polioptila melanura" (On-line), Animal Diversity Web. Accessed February 12, 2012 at http://animaldiversity.ummz.umich.edu/site/accounts/information/Polioptila_melanura.html

Disclaimer: The Animal Diversity Web is an educational resource written largely by and for college students. ADW doesn't cover all species in the world, nor does it include all the latest scientific information about organisms we describe. Though we edit our accounts for accuracy, we cannot guarantee all information in those accounts. While ADW staff and contributors provide references to books and websites that we believe are reputable, we cannot necessarily endorse the contents of references beyond our control.

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