Temporal variation in aggression and courtship behaviour in a breeding colony of king penguins (Aptenodytes pentagonicus) in Diergaarde Blijdorp, Rotterdam

Abstract

Choosing the right partner to reproduce with is an important aspect of a sexually reproducing animal’s life, therefore mate choice is very important: a suitable partner could safeguard the representation of the genes of the individual in the next generation. Many species are dependent on sexual reproduction to make sure their genes are represented in the next generation and therefore need to find a suitable mate. In many bird species the parental investment of both parents is needed to ensure successful fledging of the chicks. Even when certain bird species form monogamous pairs, they can be part of a larger social group with its own social structure, as is the case of colony-breeding birds. This social structure is defined as all social interactions within the social group and can change over time. One example of such a colonial breeder is the king penguin (Aptenodytes pentagonicus). They are serial monogamist and pair with only one mate for that breeding season. To find a suitable mate, they undergo a courtship period in which both males and females choose their partner based on behavioural, visual and auditory cues. With these cues they choose mates assortatively. Assortative mating is choosing a mate by an individual based on(phenotypical) similarities to as itself. In captivity king penguins live in permanent colonies and are therefore subject to other circumstances than in the wild. Where wild king penguins can leave their colony, are subject to harsh winters and other weather conditions, captive penguins live in climate controlled enclosures which they cannot leave. To see if social structure in captivity would differ from the wild, the aim of the study was to 1. investigate how the social behaviour of captive king penguins changes at individual level over time to see what influence the breeding season has regarding to both aggressive as well as courtship behaviours. 2. investigate if there is assortative mating based on timing of moult and age, as is the case in wild king penguins. And 3. investigate if pair formation influences social proximity. For this I studied a colony of captive king penguins in Diergaarde Blijdorp, Rotterdam and divided the total observation period in three subperiods: pre-moult, post-moult and the post-egg period. I found more courtship behaviour in the post-moult period than in the pre-moult period. I found more aggression in both the post-moult and the post-egg period compared to the pre-moult period. Furthermore, I found a trend that pairs had more similar timing of their moult than non-pairs. I found no effect of age on pair formation. Moreover, I found that pairs stood together more than non-pairs in all time periods. Looking at all results it seems that captive king penguins follow similar behavioural patterns as their wild counterparts, because the results are similar to what was found in wild king penguins.