Chicken Cuckoo just left the nest
Spring is approaching and within a few days will begin to hear the familiar call of the cuckoo (Cuculus canorus ) in our fields. The cuckoo is a species known worldwide for its particular form of reproduction, since they do not raise their chickens but lay their eggs in the nests of other insectivorous birds for them to care for them. This task is not simple and contrary to what might appear to require much effort to search for nests and monitoring appropriate partners of prospective adoptive parents. And of course the cuckoo females should ensure that they put their eggs at the right time, just before the start of incubation.
Over millions of years of co-evolution, parasites and guests have struggled to win the battle. About trying to get their eggs are not recognized and the other trying to unmask the impostor and avoid deception. The cuckoos have been almost perfectly mimic the size and pigmentation of eggs parasitized species and for its part, the guests have increased their ability to identify and prevent fraud, attacking on sight cuckoos near its territory and ultimately left the nest, even with the full set if you have any doubt that a suspect is egg in it (Pozgayová et al, 2010). Always be less expensive to conduct a fantastic replacement to miss a breeding season feeding the son of a stranger.
But once the female cuckoo has an egg in the appropriate nest success is still not insured. You should now be the little cuckoo who has to fight for their survival. The parasite egg is incubated by adoptive parents until they hatch, and within minutes of being freed from the shell instinctively expel the contents of the nest. The newborn will support your feet on the bottom of the nest and bear eggs on their backs, and even other chicks of their adoptive parents and throw them out.
Movements expulsion of eggs and chicks from the nest (taken from Anderson et al, 2009)
This task can take over an hour and will cause a huge loss of energy which will recover quickly (Anderson et al, 2009). Anyway, this effort will be richly rewarded, because from that moment the little cuckoo is the owner and master of the nest, and their foster parents work tirelessly to provide all the food necesariohasta to complete its development.
But all this strategy is a small limitation. Ritualized behavior and innate expulsion of the contents of the nest only lasts a few hours after hatching so it is essential that the cute little their siblings born before or little after, as otherwise these would be too large to be expelled from the nest.
development of newly laid cuckoo eggs (above) and zebra finches recent positions (middle) and after 24 hours of incubation.
In a recent article by Tim Birkhead group , these researchers examined the degree of development of eggs of several species of cuckoo in the time of release and compared it to the state of development of eggs other species of birds (zebra finches, doves, etc) at different times of incubation.
The results were surprising, because it found that the parasitic bird species retained the egg for 24 hours in the oviduct Once formed, so at the time of commissioning stage of development was similar to eggs that had been incubated for a day or even longer. This incubation intracorporeal was achieved in part through these parasite species had an interval between egg laying and egg 48 hours, while non-parasitic species of passerine put an egg a day. This fantastic range allowed the eggs remain inside the mother at a temperature of 40 º C for an extra day so that the incubation period by the adoptive parents was reduced. References
Anderson MG, Moskát C, Ban M, Grim T, Cassey P, & Hauber ME (2009). Egg eviction impossible in Recoverable cost of virulence in chicks of a brood parasite. PloS one, 4 (11) PMID: 19907639
Birkhead TR, Hemming N, Spottiswoode CN, Mikula O, Moskát C, Ban M, & Schulze-Hagen K (2011). Internal incubation and early hatching in brood parasitic birds. Proceedings. Biological sciences / The Royal Society, 278 (1708), 1019-24 PMID: 20880882
Pozgayova, M., Prochazka, P., Polacikova, L., & Honza, M. (2010). Closer inspection clutch - quick egg ejection: timing of host responses parasitic eggs Toward Behavioral Ecology, 22 (1), 46-51 DOI: 10.1093/beheco/arq163
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