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When N = 1 is enough

Our zoological knowledge is highly unbalanced in terms of geography. In the case of birds, we know a lot about a few European or North American species, whereas for the majority of bird species in Africa or South America our knowledge is very limited. In this short note we bring to light some data that was collected and analysed years ago (1997), but that we thought too anecdotal to deserve publication. On second thoughts we realised that it was interesting in itself, and also as a tell-tale of how interesting discoveries may arise.

Robin-chats are a group of thrush-like African species who inhabit forest edges and open woodlands, but also urban parks and gardens. While doing research on a duetting bird in Gambia, we (that is: Peter Slater, Patrcik Sellar, Clive Barlow and Diego Gil) found a nest of white-crowned robin chats (Cossypha albicapillus). We started observing the adults that were feeding the young and soon we realised that there were many birds feeding, not just the expected couple. 

We decided to place a net in the area, capture and mark the adults and then observe who was feeding the chicks. To our surprise we observed 5 different adults feeding the two chicks that the nest contained. This bird is supposed to be monogamous, so this instance of cooperative breeding was a surprise to us!

We took blood samples of the adults and the nestlings, and back in St. Andrews, Jeff Graves and Helen Balfry tried some parentage genetic markers. Although only one of the markers worked, this was enough to suggest that the nestlings had at least two different fathers, suggesting multiple paternity in this species.

Obviously, one single nest and one single genetic marker do not allow us to go too far in the study of the mating system of this species, but at least shows that cooperative breeding and multiple paternity do exist.

It would be great if we could go back to West Africa and do a more extensive study; cooperative breeding is a fascinating topic. If this is not possible, hopefully someone who reads this may increase that n = 1 in the future: which individuals are cooperative breeders?, are helpers genetically related to the parents?, do they become breeders later in life?, are the multiple fathers members of the same group?... so many open questions by the discovery of a single nest.

Diego Gil




  • White-crowned robin chat in the hand
  • A sweaty, very young Diego writing field notes by candlelight