Host species of brood-parasitic birds can evolve features such as spots, squiggles and colours on their eggs that act like ‘signatures’ that are difficult for parasites to forge, helping hosts to detect and reject imposter eggs. In this new paper, we show that hosts of cuckoo finches and diederik cuckoos in Zambia have optimised this defence by arranging signature traits in unpredictable combinations. Thus, egg signatures are individually distinctive and hard for parasites to mimic, helping hosts distinguish parasitic eggs from their own. The paper arose from MPhil research by Eleanor Caves (co-authored by Martin Stevens, Edwin Iversen and Claire Spottiswoode) and the data were all obtained from Major John Colebrook-Robjent‘s wonderful egg collection. It is available open access in Proceedings of the Royal Society of London B.
New paper on imperfect egg mimicry
Our paper “Combined measures of mimetic fidelity explain imperfect mimicry in a brood parasite-host system” has just been published in the journal Biology Letters. This study was led by Tanmay Dixit, and carried out together with Gary Choi, Salem al-Mosleh, Jess Lund, Jolyon Troscianko, Collins Moya, L Mahadevan, and Claire Spottiswoode, as part of a collaboration between our group and Prof. Mahadevan and his lab at Harvard University. Together we combined mathematical tools and field experiments in Zambia to quantify a key difference – “squiggle” markings – between the eggs of hosts (tawny-flanked prinias) and parasites (cuckoo finches). We showed that suboptimal behaviour on the part of prinias allows cuckoo finches to get by with an imperfect copy of prinia eggs.