Sociality of Hens

This Turkey Tuesday is about sociality in hens as the breeding season starts. We know that once hens leave winter flocks, they form small social groups with several other hens. These social groups hang around together prior to the onset of laying, during which time they breed with toms and identify areas within their breeding range where resources are most plentiful. Ongoing genetics work by Sara Watkins dove into specifics about members of these social groups, to see how these birds behave as breeding season progresses, and to determine if hens within these groups are related. Here’s some interesting results. First, 67% of all contacts within a social group occur before laying starts. Once laying begins, there is a 95% decrease in sociality – < 3% of total contacts amongst hens happens once they start laying. Second, 94% of all contacts occurred between hens that are not related. These results suggest that hens perceive a cost associated with spending time with kin once reproduction starts, which is really interesting. This second picture is of a parasitized nest in Texas, some hens will lay eggs in other hen’s nests while also nesting on their own – we see this in all populations. Previous research showed that birds that parasitize each other spend time together while they’re in the laying sequence, and I’ve speculated that perhaps those hens were related. Alas, it appears that most are not. Future work should tease more out about this topic. But it makes me wonder whether parasitism is more driven by predation risk – maybe hens nesting in areas with higher predation risk both to the nest and herself are more likely to put eggs in someone else’s basket.

Picture of hens © Tes Randle Jolly

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