5/6/2023 0 Comments Song sparrowSong Sparrows often lay two or more clutches of eggs per breeding season.A study found that male Song Sparrows from the coast of Washington state came into breeding condition two months earlier than Song Sparrows in the nearby mountains, where the daylight changes were the same, but temperatures were cooler and trees budded out two months later. But, other cues can be important too, such as local temperature and food abundance. The Song Sparrow, like most other North American breeding birds, uses increasing day length as a cue for when to come into breeding condition.The darker plumage contains more of a pigment called melanin, which makes feathers tougher and harder to degrade than lighter, unpigmented feathers. Some scientists think that Song Sparrows of wet, coastal areas have darker plumage as a defense against feather mites and other decay agents that thrive in humid climates.Males that used more learned components in their songs and that better matched their song tutors (the adult bird they learned their songs from) were preferred. Laboratory studies have shown that the female Song Sparrow is attracted not just to the song itself, but to how well it reflects the ability of the male to learn. Like many other songbirds, the male Song Sparrow uses its song to attract mates as well as defend its territory.High rates of immigration and emigration may keep populations genetically similar, while local selective conditions maintain the physical differences. Despite the large differences in size and coloration across the Song Sparrow’s range, genetic divergence is low.Field researchers working for many years on the same parcels of land have noticed that some choice spots – the base of a rose bush, or a particular hollow under a hummock of grass, for example – get used over and over again, even when entirely new birds take over the territory. Song Sparrows seem to have a clear idea of what makes a good nest.These Song Sparrows have white throats and chests with black streaks. There’s also an isolated population that lives on the plateau of central Mexico, about 900 miles from the next closest population. The range of the Song Sparrow is continuous from the Aleutians to the eastern United States.Song Sparrows of Alaska’s Aleutian Islands chain are even darker, and they’re huge: one-third longer than the eastern birds, and weighing twice as much. Song Sparrows of the Desert Southwest are pale, while those in the Pacific Northwest are dark and heavily streaked. The Song Sparrow is found throughout most of North America, but the birds of different areas can look surprisingly different.
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