Size‐assortative nest preference in a paternal brooding blenny Rhabdoblennius ellipes (Jordan & Starks)

Abstract

Field and laboratory studies were conducted to clarify the processes contributing to the size‐assortative nest use by males of a paternal brooding blenny Rhabdoblennius ellipes. The use of natural and artificial nests by males in the field was highly size‐assortative; males used smaller nests even when larger nests were available. Aquarium nest choice experiments without a competitive male strongly suggested that the size‐assortative nest use by males is not the result of male–male competition for larger nests, but male preference for size‐matched nests. Males were likely to choose nests on the basis of the nest entrance size rather than nest length and volume, suggesting that the size‐assortative nest preference in this species is an adaptation to predation pressure against eggs and resident males.