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The bluebirds are a North American [1] group of medium-sized, mostly insectivorous or omnivorous birds in the order of Passerines in the genus Sialia of the thrush family (Turdidae). Bluebirds are one of the few thrush genera in the Americas. Bluebirds lay an average of 4 to 6 eggs per clutch. They will usually brood two or three times in a year.
Eastern bluebirds measure 16–21 cm (6.3–8.3 in) long, span 25–32 cm (9.8–12.6 in) across the wings, and weigh 27–34 g (0.95–1.20 oz). [12] [11] Male bluebirds have a bright head, back, and wings. Their breast is a brownish red. [12] Females are lighter with gray on the head and back and some blue on their wings and tail.
Adult female in Livermore, California. The western bluebird is a small stocky bird with a length of 15 to 18 cm (5.9 to 7.1 in). The adult male is bright blue on top and on the throat with an orange breast and sides, a brownish patch on back, and a gray belly and undertail coverts.
The direct benefits of land transformation for the growing world population often make it ethically difficult to justify the tradeoff between biodiversity and human use. [14] Reconciled ecosystems are ones in which humans dominate, but natural biodiversity is encouraged to persist within the human landscape.
Out of all known bird species, (approximately 11,154), 159 (1.4%) have become extinct, with 226 (2%) being critically endangered. [1] There is a general consensus among ornithologists that if anthropogenic activities continue as current trends suggest, one-third of all bird species, and an even greater proportion of bird populations, will be ...
According to the International Union for Conservation of Nature (IUCN), 77 bird species in the United States are threatened with extinction. [1] The IUCN has classified each of these species into one of three conservation statuses: vulnerable VU, endangered EN, and critically endangered CR (v. 2013.2, the data is current as of March 5, 2014 [1]).
A threatened species is any species (including animals, plants and fungi) which is vulnerable to extinction in the near future. Species that are threatened are sometimes characterised by the population dynamics measure of critical depensation, a mathematical measure of biomass related to population growth rate.
Diagram of Lower Risk / near threatened in the older IUCN version 2.3, beside the former Lower Risk / conservation dependent subcategory.. Before 2001, the IUCN used the version 2.3 Categories and Criteria to assign conservation status, which included a separate category for conservation-dependent species ("Conservation Dependent", LR/cd).