Research Interests
Prey capture and handling behaviour in Australian fur seals from David Hocking on Vimeo.
Evolution of feeding mechanics and behaviours in marine mammals
My primary research interest involves using a combination of anatomy, functional morphology and behaviour to look at when, how and why different species of marine mammals have come to specialise on different prey types when living in complex marine ecosystems. There are three main ways that a marine mammal can feed under water; Raptorial feeding (biting and snapping), Suction feeding and filter feeding. Different species use these methods for specialising on different prey types, however there is often considerable overlap in diet. I am particularly interested in the case of the Antarctic leopard seal, a generalist predator, which appears to be using a combination of all three prey capture strategies over the course of a year depending on the prey species available.
I use a comparative approach and am interested in studying the feeding behaviours displayed by a wide variety of marine mammals so that the general trends in feeding ecology and behaviour can be distinguished. Thus far my research has focused on the Antarctic leopard seal, using the Australian and sub-Antarctic fur seal and the Californian sea lion as comparative taxa. In future work however, I also hope to incorporate the Australian sea lion, elephant and Weddell seals and some odontocete whales species (Odontocetes are a good comparative taxa for pinnipeds, as a group they also display a wide range of feeding strategies).
Leopard seal during feeding trials
Animal enrichment and the maintenance of wild behaviour in captive animals
It is very difficult to study the feeding mechanics of marine mammals in the wild due to the difficulties in first locating the animals and then in safely documenting their behaviours in the open ocean. For this reason it is important to take advantage of having access to captive animals in conservation parks and zoos. One of the difficulties with using captive animals however is in determining which of the displayed behaviours the animals have learned from their captive environment, and which behaviours can be taken as approximations of natural wild behaviours.
Foraging based enrichment for Australian Fur Seals from David Hocking on Vimeo.
This has led me to having a great interest in how institutions, such as zoos, can use animal enrichment and training to encourage and maintain wild behaviour in captive animals. As researchers performing feeding trials with captive seals, we are actively adding new types of enrichment to the seals environment. This provides us with an opportunity to study not only the feeding mechanics and behaviours, but also the seals patterns of activity and how the range of displayed behaviours is affected by adding new kinds of enrichment. This has implications for both for the wild behaviours in study species and also for how we should design and manage enrichment programmes so that they best promote natural wild behaviours.
Leopard seal during training, Taronga Zoo.
Mainland Australia visitation by vagrant Antarctic leopard seals
Every year a small number of young leopard seals head northward to the mainland of the southern continents including Australia. These seals are often in poor health and often do not survive to return to the Antarctic. These visits provide us with a unique opportunity to look at how this large generalist predator behaves when it is outside its normal feeding grounds. I am particularly interested in the diet individuals which have been found to frequent the little penguin (Eudyptula minor) colonies along the south coast of Australia where they have been documented to take a large number of penguins during their stay at a colony. To study these seals we must record the number of sitings that are made and where possible collect scats from haul out sites so that they can be analysed to determine what the seal has been eating.
17th January 2011 - Cape Paterson, Victoria
Tooth shape and the evolution of feeding modes in fossil marine mammals
Research into the feeding behaviours of modern marine mammals can have important implications for our understanding of animals from the fossil record. One of my main areas of study is looking at the impact of tooth shape on the feeding function of teeth in pinnipeds, in part, because of the implications this has for our understanding of feeding in early toothed mysticete or baleen whales.
Today, all Baleen whales display some form of bulk filter feeding, using keratinous baleen plates to strain prey out of seawater. The earliest baleen whales however have been found to have well developed dentition. Because of this it has been proposed that the earliest baleen whales may in fact have used their teeth as a sieve to filter feed on small prey in much the same way that has been proposed for the crabeater and leopard seal. Our work has aimed to assess whether it is justifiable to use these modern "filter feeding" pinnipeds as modern analogues for these early whales by looking at tooth shape in each of these species using 3D morphometric analyses.
3D Tooth Models: Left- Leopard Seal 3rd postcanine, Right- Llanocetus denticrenatus postcanine. Scale sphere=2mm