Leopard seals have 5 different calls from high pitched cricket like trills to low haunting moans. During the summer the waters of the Antarctic pack ice echo with the calls of the leopard seals singing to one-another underwater. Marlee collected information which will be used to help calculate the density of the Leopard seals in the area by eavesdropping on their singing.

This information will then be related back to environmental characteristics to examine which are the important features that are important to the seals. The first aim of Marlee’s acoustic work was to record the characteristics and structure of the West Antarctic Leopard seal calls.

The second aim was to play back calls from other leopard seals, to see their reaction, if any. To date, playbacks have never been done in the wild with leopard seals before. With an understanding of the seals calling patterns models can be used to turn the number of calls into numbers of seals. But to do this researchers need to be able to calculate various features such as calling rates, ie. how stereotyped are the patterns that the seals produce these calls, and does this calling rate change in the presence of other calling seals (this is why Marlee was doing the playbacks), also, how loud are the calls (measuring their source levels) so we can model how far we would be hearing the calls.

All of the recordings were taken at a depth of around 5 metres using hydrophones and underwater speakers both from ‘Australis’ and the Zodiacs. These recordings and findings will go towards a much larger project examining how the top predators (seals and whales) are responding to the warming on the Western Antarctic Peninsula, by Marlee’s PhD supervisor Tracey Rogers and her team at the Evolution and Ecology Research Centre at the University of NSW. Initial observations found that there are differences in call characteristics between the East and West Antarctic Leopard seals, but this will be examined in more detail now that these recordings have been collected.