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This concentration of birds during migration can put species at risk. Some spectacular migrants have already gone extinct, the most notable being the passenger pigeon . During migration the flocks were a mile (1.6 km) wide and 300 miles (500 km) long, taking several days to pass and containing up to a billion birds.
[34] [35] However most bird migration is in the range of 150 to 600 m (490–2,000 ft). Bird strike Aviation records from the United States show most collisions occur below 600 m (2,000 ft) and almost none above 1,800 m (5,900 ft). [36] Bird migration is not limited to birds that can fly. Most species of penguin (Spheniscidae) migrate by ...
It is greatest before migration at the end of the breeding season. The female is generally slightly heavier than the male. [9] It is streaked brown with a white eyestripe, and, in the male, a white chin. As befits its migratory nature, it has long wings, unlike the typically short-winged gamebirds.
The common nighthawk winters in southern South America, but distribution in this range is poorly known due to difficulties in distinguishing the bird from the lesser nighthawk and in differentiating between migrants and overwintering birds. In some South and Central American countries, a lack of study has led to restricted and incomplete ...
Other fruit bat species include the greater and lesser short-nosed fruit bat, Blanford's fruit bat and the cave nectar bat. Fruit bats are sometimes considered pests by fruit farmers, and are hunted and eaten in parts of Guangdong, Guangxi and Hainan. [237] They also help pollinate certain species of tropical fruit trees. [238]
Like all bats in the United States, [54] big brown bats can be affected by rabies. The incubation period for rabies in this species can exceed four weeks, [55] though the mean incubation period is 24 days. [54] Rabid big brown bats will bite each other, which is the primary method of transmission from individual to individual.
The black kite was described by the French polymath Georges-Louis Leclerc, Comte de Buffon in his Histoire Naturelle des Oiseaux in 1770. [3] The bird was also illustrated in a hand-coloured plate engraved by François-Nicolas Martinet in the Planches Enluminées D'Histoire Naturelle which was produced under the supervision of Edme-Louis Daubenton to accompany Buffon's text. [4]
Straw-coloured fruit bats travel in massive colonies of at least 100,000 bats and sometimes massing up to 1 million. From October to end of December every year, in the largest migration of mammals on the planet, up to 10 million straw-coloured fruit bats congregate in Kasanka National Park , Zambia , roosting in a 2 hectares (4.9 acres) area of ...