Differences in Diving Behaviour Optimality May Cause Differences in Reproductive Success in Chinstrap Penguins: A Cases Study

Bio-logging is a useful technique for obtaining information on foraging behaviour, physiology, and environ- mental conditions from animals in marine ecosystems. By integrating this information, researchers can investigate the ecology of general prey-predator system in terms of their optimal behaviour with the help of theoretical models. In the present study, I analyse the diving behaviour of two chinstrap penguins using an index of diving behaviour optimality as a case study. Because of small sample size in the study, I demonstrate possibility to prove the association between calcu- lated optimality index and breeding success in birds and how it basically would be possible if more individuals would be included in analyses. This index is the proportion of observed dive time to "standard" dive time. Standard dive time is de- fined as an "optimal" dive time that maximises the proportion of bottom time to the duration of a dive cycle for a given travel time. Using this index, I found a difference in the optimality of diving behaviour and prey conditions experienced between birds, which may cause differences in chick growth rate. Because many dives have already been recorded using bio-logging techniques, using this index to analyse diving behaviour could give new insights into the foraging ecology of top predators in marine ecosystems.