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Female birds are able to produce more of a certain gender of birds that are more likely to survive under extreme conditions. In birds, the females' egg determines the gender of the offspring, not the male's sperm. In zebra finches, a study showed the effect of food on gender ratio production. For females, egg production is a metabolically ...
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.
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.
A boa constrictor in the U.K. gave birth to 14 babies — without a mate. The process is called parthenogenesis, from the Greek words for “virgin” and “birth.”
In birds, this parental care system is generally attributed to the ability of male birds to engage in most parental behaviours, with the exception of egg-laying. Due to their endothermy and small size at birth, there is a huge pressure for infant birds to grow up quickly to prevent energy loss.
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.
Altricial birds are less able to contribute nutrients in the pre-natal stage; their eggs are smaller and their young are still in need of much attention and protection from predators. This may be related to r/K selection; however, this association fails in some cases. [18] In birds, altricial young usually grow faster than precocial young.
Deep cup nest of the great reed-warbler. A bird nest is the spot in which a bird lays and incubates its eggs and raises its young. Although the term popularly refers to a specific structure made by the bird itself—such as the grassy cup nest of the American robin or Eurasian blackbird, or the elaborately woven hanging nest of the Montezuma oropendola or the village weaver—that is too ...