Roosters are nicer to their relatives than to other males

Date: March 29, 2017

Source: Linköping Universitet

Male domestic fowl are less aggressive towards related males than to unrelated males when competing for copulations, according to a new study from Linköping University in Sweden. This finding, which has been published in the scientific journal Behavioral Ecology, suggests that domestic fowl can recognise their kin among individuals in a group, and that their behaviour is different towards kin and non-kin.

Domestic fowl in groups form a strict hierarchy, with one rooster being dominant over the others. The roosters compete for access to hens to mate with, and in this way produce offspring and transmit their genes to the next generation. If a rooster that is lower in the ranking attempts to mate with a hen, the dominant male will often interrupt and abort the mating attempt.

The researchers who conducted the study investigated if roosters not only attempt to produce offspring themselves but also to help relatives to do so. From an evolutionary perspective, this would be a way of ensuring that at least some of the male's genes are transmitted to the next generation. Particularly older males, with reduced reproductive capacity, may be more accepting towards younger relatives mating attempts. Thus, the researchers wanted to determine whether dominant roosters are more permissive towards the attempted matings of subordinate relatives than to those of unrelated lower-ranked males. They divided the chickens into groups with one dominant male and two roosters of lower rank; one of which was brother or son of the dominant male, and one that was unrelated to him. The three roosters were released together with four hens, and the researchers observed their mating behaviour.

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