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Two main types of polyandry exist: simultaneous polyandry and sequential polyandry. An even rarer subtype called cooperative simultaneous polyandry also exists in some species. In simultaneous polyandry, the female will dominate a certain territory which contains several small nests with two or more males, who take care of the offspring.
For example, the mallard (Anas platyrhynchos) is known to interbreed with at least 40 different species. The ecological and evolutionary consequences of multispecies hybridization remain to be determined. [2] In the wild, some of the most frequently reported hybrids are waterfowl, [3] gulls, [4] hummingbirds, [5] and birds-of-paradise. [6]
[9] [23] Most birds, including passerines (perching birds), have their young born blind, naked and helpless (altricial), totally dependent for their survival on parental care. The young are typically raised in a nest; the parents catch food and regurgitate it for the young.
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.
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]
Paternal care may be provided in concert with the mother (biparental care) or, more rarely, by the male alone (so called exclusive paternal care). The provision of care, by either males or females, is presumed to increase growth rates, quality, and/or survival of young, and hence ultimately increase the inclusive fitness of parents.
Some animals starve to death shortly after birthing their young while others are eaten by their own young -- but these mothers make the ultimate sacrifice. Click through for 10 animal mothers that ...
[22] [4] Ground-nesting birds employ different defensive behaviors as part of their antipredator strategies because they nest where a wide range of predators have access. It has been shown that for Kentish plovers there is a positive correlation between male and female defense behaviors within pairs and that nests in which parents invested more ...