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An audio recording of a house sparrow. The house sparrow (Passer domesticus) is a bird of the sparrow family Passeridae, found in most parts of the world. It is a small bird that has a typical length of 16 cm (6.3 in) and a mass of 24–39.5 g (0.85–1.39 oz).
With an increase in available mates in some birds (such as the rock sparrow), female desertion rate increases leading to more mono-parental care. When female rock sparrows were exposed to an abundant number of male mates approximately 50% of the females deserted their first nest when the hatchlings were on average 14.3 days old.
Allofeeding evolved for different reasons in different species of birds. While sagebrush Brewer's sparrows allofeed to reduce predation during incubation, Sichuan jays allofeed to increase a female's nutritional level prior to egg laying, and chinstrap penguins allofeed to strengthen the bond between the pair during chick guarding. [4] [5] [6]
In general smaller birds tend to hatch faster, but there are exceptions, and cavity nesting birds tend to have longer incubation periods. It can be an energetically demanding process, with adult albatrosses losing as much as 83 g of body weight a day. [6] Megapode eggs take from 49 to 90 days depending on the mound and ambient temperature.
The other significant advantage is the chance for the healthiest young animals to be favored from a group. Rather than it being a conscious decision on the part of the parents, the fittest and strongest baby competes most successfully for food and space, leaving the weakest young, or runts, to die through lack of care.
A fecal sac (also spelled faecal sac) is a mucous membrane, generally white or clear with a dark end, [1] that surrounds the feces of some species of nestling birds. [2] It allows parent birds to more easily remove fecal material from the nest.
Humans have a long history of eating eggs, both wild bird eggs and farm-raised bird eggs. [citation needed] Brood parasitism occurs in birds when one species lays its eggs in the nest of another. In some cases, the host's eggs are removed or eaten by the female, or expelled by her chick.
The span between precocial and altricial species is particularly broad in the biology of birds. Precocial birds hatch with their eyes open and are covered with downy feathers that are soon replaced by adult-type feathers. [17] Birds of this kind can also swim and run much sooner after hatching than altricial young, such as songbirds. [17]