Animals can decode several meanings from signals about self including: parent-offspring recognition, kin recognition, mate recognition, stranger/individual recognition, competitive status, motivational status, genotypic & phenotypic quality, and aposematic colouring. Parent-offspring recognition is especially apparent in colonial bird species such as bank swallows and emperor penguins. Both species need to leave the nest to get food for their offspring, and when they return, they locate their nests based on their chick’s calls. Kin recognition is present in birds as apparent through incest avoidance behaviour. Great tits will recognise the calls of their fathers and avoid mating with birds who have an identical call as this avoids the possibility of incest. Tadpoles will secrete a hormone that other tadpoles recognise as belonging to their kin and will form groups with similar genomes. Mate recognition has been shown to occur in bird species who have to return to a nesting site. In some species of gulls, males will return to nesting sites first and emit a call which their mates will recognise. Song birds have been shown to recognise different individuals. White-throated sparrow males can recognise whether a neighbour emits a call from a familiar border or if it has moved to a new location and threatens to encroach on his territory. In the former case, the male will respond weakly to the neighbour relative to his response to a stranger from the same location. In the latter case, the male will respond just as strongly to the neighbour in the new location as to a stranger from that same location. Competitive status is an important message to decode in dominance hierarchies. In house swallows, dominant males will have more black feathers on their head and chest than submissive males. Motivational status often has to do with level of aggression or sexual motivation. In canids, different facial expressions will give a receiver different information about the likelihood that the canid’s next action will be aggressive or submissive. In hook-tipped moths, male caterpillars will emit sound from different places on their bodies to ward off other males. Signals also communicate genotypic and phenotypic quality as in the springbok’s stottering behaviour. A springbok stotters by jumping up and down to highlight the black and white stripe on his flank. In doing so, the springbok not only signals to the predator that he has been detected but also tells them he is healthy and that it will take great effort to capture him. Lastly, aposematic colouring has to do with how poisonous or venomous a creature is. Bright, contrasting colours often indicate that an animal will be inedible or produces lethal toxins. For example, the hooded pitohui has bright orange and black feathers to signal that it produces batrachotoxin that will kill the predator that tries to eat it.
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