Blue-black grassquit


The blue-black grassquit is a small bird in the tanager family, Thraupidae. It was previously classified in the bunting and American sparrow family, Emberizidae. It breeds from southern Mexico through Central America, and South America as far as northern Chile, Argentina and Paraguay, and on Trinidad and Tobago. It is the only member of the genus Volatinia.

Description

Adult blue-black grassquits are long and weigh. They have a slender conical black bill. The male is glossy blue-black, with a black tail and wings; the white inner underwing is visible in flight or display. Female and immature birds have brown upperparts and dark-streaked buff underparts.

Behavior

Social monogamous, extra-pair fertilizations, intraspecific parasitism, and quasi-parasitism are commonly found. During the breeding season, males defend small territories, about 13,0 - 72,5 m2, dominant males are normally lighter. The male has a jumping display, often performed for long periods, which gives rise to the local name "johnny jump-up". This is accompanied by a persistent wheezing jweeee call, jumping several times in a minute. The extravagant display also has a cost of call attention of predator, thus displays increase the nest predation. Predation are the main cause of breeding failure, and predator vocalizations can cause immune-related reaction to this species. Nests are small cups of rootlets found at herbaceous vegetation 10–50 cm high, clustered at landscape, and placed preferably at high complex habitat spots. Nests are built by both sexes.