Recently, there have been endless incidents of replacing others to go to college, and the life of the replaced has been tampered with, and the attitude of the replacement is arrogant. However, among the cute and beloved birds, there are also shameless people who replace other people's lives, and "substitution" seems to be their way of survival.
Nest parasitism: You help me raise my children!
In the last issue we talked about nest encroachment, but nest parasitism is a more excessive "substitution method", nest parasitism refers to some birds, not only do not "build their own houses", but also secretly lay eggs in the nests of other birds, other birds do not know that they let them hatch and breed a breeding behavior. In this kind of behavior, the most "infamous" is perhaps the great cuckoo (cuculus canorus, also known as the cuckoo), the "Compendium of Materia Medica" says that "the dove can not be a nest, live in his nest to give birth", describing the "evil deeds" of the great cuckoo.
"Substitute repeat offender" big cuckoo
The crow, the reed warbler, the sparrow, the grey magpie, the berau, the brown-headed crow, the northern red-tailed plover, the brown fantail warbler, the gray-footed willow warbler, etc. are all "replacement" objects of the great cuckoo. The breeding period of the great cuckoo is generally from May to July, and during this breeding period, the female will put an egg in the nest when the birds are not paying attention, and take away one of the eggs of the owner of the nest.
The eggs of the great cuckoo and the eggs of the owner of the nest
The tragic fate of the "replaced"
The big cuckoo can be said to be a "natural villain", the chick is larger than the nest owner's chick as soon as the shell is broken, and it is common to squeeze the nest owner's own chick out of the nest and fall to death, monopolizing the love of the "parents". Nest owners not only have no knowledge, but also work hard to hatch and raise these chicks that are not their own. In the wild, smaller birds can often be seen feeding large cuckoo chicks that are much larger than their own size. When the big cuckoo chicks grow up, they fly away without turning back.
Male birds of the Northern Red-tailed Plover were observed in the Huayang Conservation Station feeding the Great Cuckoo Chicks
The male bird of the Northern Red-tailed Plover was observed at the Huayang Conservation Station feeding a large cuckoo chick
Cunning "replacement"
In addition to the great cuckoo, there are many birds with nest parasitic behavior, such as the four-voiced cuckoo (C. cuckoo). micropterus), hierococcyx sparverioides, birds of the genus Molothrus, birds of the genus Vidua, etc. In the process of choosing a host for these birds is very cunning, the great cuckoo will be judged and selected from a variety of factors, including the nest owner's ability to recognize eggs, the time of reproduction, the quality of the habitat, the characteristics of the nest site and the food type of the nest owner, etc., for example, the eggs of the oriental reed warbler are similar to the eggs of the great cuckoo, and the study found that more than half of the reed warblers cannot distinguish their own eggs and the eggs of the parasites. In addition, the large cuckoo lays eggs very quickly, only half the time (about 10 seconds) of the average bird, as long as the nest owner is slightly inattentive, it can "steal the day".
The silly reed warbler is feeding a large cuckoo chick that is much larger than itself
Is the "replaced" unaware of the substitution?
Doesn't the nest owner know anything about these cunning "substitutes"? On the one hand, some birds choose to build their nests in a more hidden place; on the other hand, some birds can gradually learn to recognize the eggs of the great cuckoo through acquired learning or parental inheritance, or when the chicks of the "replacement" grow up, they realize that "this child does not look like me" and refuse to continue feeding.
Females of the Northern Red-tailed Plover observed co-brooding at the Huayang Conservation Station refuse to continue feeding the Great Cuckoo Chicks
Despite the suspicions of the mates, the male has insisted on feeding the natives of Huayang
It is illegal to replace others to go to college, and it takes a price to replace others, but the "substitution" of birds is a phenomenon that exists in nature, and there is also a competitive and co-evolutionary relationship between the "substitute" and the "replaced", the parasite continues to improve the level of the egg's camouflage, and the host continues to improve its level of identifying the parasite's egg.
bibliography:
Campobello D, Sealy S G. Enemy recognition of reed warblers (Acrocephalus scirpaceus): threats and reproductive value act independently in nest defence modulation[J]. Ethology, 2010, 116(6): 498-508.
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