For 2 weeks in March this year Charlotte Dunn volunteered aboard the Balaena, 40 foot sailing vessel, to help with field-work and data collection for a PhD student from Dalhousie University, Shane Gero. Shane is in Hal Whitehead's lab, and is studying sperm whale social structure and acoustic communication of resident sperm whales off the island of Dominica in the West Indies.

Also on board were Dr Luke Rendell, Lesley Thorne, a PhD student from Duke University, and Susanna, a recent graduate from the University of St Andrews Marine Mammal MRes course.

The study is focusing on behavioural ecology of sperm whales by correlating acoustic activity made by the whales with visual observations of their surface behaviours. In order to achieve the most effective results the animals are tracked 24 hours a day, whenever possible, using two acoustic methods; a combination of a towed hydrophone array and IFAW's Rainbow Click software program and a manual directional hydrophone. Constant tracking helps to maximise time spent with the animals during daylight hours, which allows researchers to obtain valuable photo-identification photographs of the whales. By obtaining a high quality photograph of the fluke (tail), individuals can be distinguished by nicks in the trailing edge. The id photos can be used to match acoustic recordings to units of whales, that is groups of often related females and immature whales living together for many years. The recordings can sometimes be matched to known individuals, and one of Shane's research questions is whether there are individual differences in acoustic characteristics that can be attributed to a whales age or sex.

Once an animal does a dive, causing its fluke to break the surface and hopefully allowing a photograph of good quality to be obtained, there can sometimes be faeces or sloughed skin left in the area of water where the animal was last seen - these samples can be retrieved using a net and then used for genetic and prey analyses.

This study will help to further our understanding of the diversity of cetacean communication and social structure.

Some of the publications that have come from sperm whale research in Dominica:
S. Gero, D. Engelhaupt, L. Rendell, and H. Whitehead (2009) Who Cares? Between-group variation in alloparental care-giving in sperm whales. Behavioral Ecology 20(4): 838-843. DOI:10.1093/beheco/arp068

T.M. Schulz, H. Whitehead, S. Gero, and L. Rendell (2008) Overlapping and matching of codas in vocal interactions between sperm whales: Insights into communication function. Animal Behaviour 76: 1977-1988. DOI: 10.1016/j.anbehav.2008.07.032

S. Gero, D. Engelhaupt, and H. Whitehead (2008) Heterogeneous associations within a sperm whale unit reflect pairwise relatedness. Behavioural Ecology and Sociobiology 63: 143-151. DOI: 10.1007/s00265-008-0645-x