For males and females blue forty (Cyanopica cyanus) the collapse of the pair carries different implications, and they depend on how experienced the new partners birds reported in Current Zoology. From the point of view of reproductive success is better if the females after the rupture of ties with the old male find a new inexperienced. Males new contacts with inexperienced females at the same time on favor does not go — but sometimes they have no choice.
For animals the formation of long-term couples is primarily a way to share resources on growing offspring. If the contribution of some partners is greatly reduced (for example, he is older and cannot produce as much food as before), it may be rational to break an Alliance with him, than to spend resources on maintenance.
Blue magpies — corvids birds living on the Iberian Peninsula and in East Asia. They form groups in which to settle very close to each other (20-180 nests per hectare). Although they protect the nest together, bring food to the nestlings almost exclusively their own parents and not other members of the colony.
From Cyanopica cyanus, like many other birds, a high percentage of “illegitimate children”. That is, the males, without knowing it, can feed Chicks from other males, and females have to sit through someone else’s eggs. In such cases, the adult birds spend their resources, roughly speaking, in the wrong genes, it makes little sense in terms of efficiency of reproduction. So in theory individuals who often exploit thus, it is better to leave the existing Union and to look for another partner.
Researchers from Lanzhou University headed by Bo Du (Du Bo) found in some cases, divorce (in the scientific article used the term divorce) is really good for blue forty. This video from 2011 to 2019 watched one of the colonies of these birds on the Tibetan plateau. Forty-labeled with coloured rings on the legs and then distinguish them. The birds were weighed and they took blood samples. DNA from the blood was later determined the relationship of birds and their “illegitimate children”.
Blue magpies hibernate not where breed, and in April, often returning there, where was their nest last year. So every spring zoologists checked the part of couples and mentioned, who changed partner and to whom. Neocolony birds and those who formed with them a couple, did not take into account in the final statistics.
In addition to the data on dissolution of each pair took into account how many eggs were in the nest of this pair (and then new pairs of each bird) what percent of Chicks survived to sexual maturity, what mass they had at the same time, how old were the parents themselves. These data have built a generalized linear model to understand which factors correlate with the frequency of extramarital Affairs, and the decay of pairs.
Only thus, scientists have tracked the fate of the 307 pairs that failed to lay eggs. Of these, 68 percent (208 pairs) raised at least one chick. An annual average of 72 percent of the terminated marital relationship. The probability of decay of a pair did not correlate with the number of offspring, nor with the amount of food brought by the male.
However, there was correlation with the frequency of illegitimate mating. If they are constantly resorted to by the male, the “official” pair holding harder. If cheating on the female (and it usually happened when the walls came very late or when the male already had considerable age), the likelihood of divorce was the highest. Also found a link with the experience of birds: if both partners already fed the Chicks in past seasons (either together or as part of other “families”), their Union ceased with the lowest probability. Mixed pairs frequency of divorces was about the same as if both birds were inexperienced.