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The common blackbird occurs at elevations of up to 1,000 m (3,300 ft) in Europe, 2,300 m (7,500 ft) in North Africa, and at 900–1,820 m (2,950–5,970 ft) in peninsular India and Sri Lanka, but the large Himalayan subspecies range much higher, with T. m. maximus breeding at 3,200–4,800 m (10,500–15,700 ft) and remaining above 2,100 m ...
A typical precocial mammal has a gestation period almost four times longer than a typical altricial mammal of the same body size. [20] Precocial mammal species generally have greater adult body weights than altricial mammals as precocial mammals have markedly longer gestation periods than altricial mammals. [21]
As the days grow longer, the longer periods of daylight cause the hormones that activate the breeding cycle to be released. As it happens, this benefits these animals in that, given a gestation period of about eleven months, it prevents them from having young when the cold of winter would make their survival risky.
The female lays three to seven eggs, with the norm being around four. The eggs are pale gray to bluish-white, measuring 2.3 cm × 1.6 cm (0.91 in × 0.63 in) on average. The incubation period is 12 to 14 days. Once the nestlings hatch, they are fed by regurgitation by both parents and brooded by the female for two weeks.
Ligon (1999) suggested with Vehrencamp (2000) that male incubation existed first and later gave way to shared and finally female only incubation. A possible evolutionary timeline by Kavanau suggests that basal theropod dinosaurs evolved into birds that evolved unique bi-parental care, after which avian birds evolved homeothermy and flight.
Gestation is the period of development during the carrying of an embryo, and later fetus, inside viviparous animals (the embryo develops within the parent). [1] It is typical for mammals, but also occurs for some non-mammals. Mammals during pregnancy can have one or more gestations at the same time, for example in a multiple birth. [2]
The red-winged blackbird (Agelaius phoeniceus) is a passerine bird of the family Icteridae found in most of North America and much of Central America. It breeds from Alaska and Newfoundland south to Florida, the Gulf of Mexico, Mexico, and Guatemala, with isolated populations in western El Salvador, northwestern Honduras, and northwestern Costa Rica.
Egg incubation is the process by which an egg, of oviparous (egg-laying) animals, develops an embryo within the egg, after the egg's formation and ovipositional release. Egg incubation is done under favorable environmental conditions, possibly by brooding and hatching the egg.