Social control of deception among status signalling house sparrows Passer domesticus

Abstract

Signalling of dominance status is a plausible explanation for variation in throat patch size in male house sparrows Passer domesticus. I tested experimentally how deception is controlled in such a status signalling system. In aviaries, experimentally dyed brids were involved in more aggressive encounters than controls. Active encounters made up a similar fraction of all interactions involving experimental and control birds. Dyed sparrows did not win relatively more encounters than controls. Experimental house sparrows were involved in more aggressive encounters with conspecifics having larger throat patches than expected whereas controls interacted with conspecifics with a throat patch size that did not deviate from expectation. The throat patch size of winning contestants was larger than that of losing birds both within and between experimental and control groups. Dyed house sparrows did not achieve higher dominance rank than controls. Cheating in the status signalling system is thus controlled socially by frequent challenges of house sparrows having large throat patches.