In 2004 he joined Animal Ecology Group, a division of Groningen and three years later became Netherlands Organisation for Scientific Research's fellow.
[1] Christiaan Both studied density-dependent reproduction during his PhD, where he aimed to understand why birds lay smaller clutches when competition increased.
[2] From 1998 Christiaan Both, Niels Dingemanse, Piet Drent and Joost Tinbergen have studied great tits' exploration and showed that this variation in personality traits is heritable.
[3] They were interested in how such variation with a heritable component could be maintained over evolutionary time, and therefore studied fitness consequences for three years in a wild population of great tits.
[7] He is mostly interested in how different organisms can respond with different mechanisms and speeds to the high rates of current climate change, and the consequences this has for trophic interactions.