Male canaries can visually eavesdrop on conspecific food interactions

Both male and female birds are known to eavesdrop on male-male vocal interactions. In contrast, males visually eavesdropping on male-male contests has been observed in fish but only suggested in birds and few avian studies have been done. We observed the behaviour of male domestic canaries, Serinus canaria, during competition for food with rivals they had or had not previously observed in dyadic contests. Males responded differentially to winners and losers of agonistic interactions they had witnessed, initiating fewer attacks against the winner and spending less time foraging. In contrast, no such effect was found when males had no prior knowledge of the relative competitive ability of the contestants. The domestic canary is, to our knowledge, the only species proven to use both visual and acoustic cues to eavesdrop.