ECOPredS project investigates predator-prey interactions between killer whales and seals (including both grey and harbour) in Scotland, in order to estimate both:
- mortality (consumption) of harbour seals by killer whales in coastal areas, and
- behaviour (non-consumptive) effects, i.e., the costs of predator avoidance by seals, and the bioenergetic costs of seal hunting by killer whales.
The ultimate goal is to better understand the (small or large) contribution of behaviour vs. mortality in the interaction, from predator/prey traits (e.g. age/size class, group size) and environmental variables. The harbour seal and grey seal provide an interesting contrast to study this, as they are closely related but with distinct foraging and reproductive strategies.
As well as collecting new data, the project will bring together and analyze existing data from collaborators and citizen scientists. The project is currently focusing on three distinct research approaches:
- Analysis of seal behaviour in relation to killer whale presence
- Behavioural (focal follow) observations of killer whales found in coastal areas
- Passive acoustic monitoring (PAM) near coastal haulout sites
Approach 1 aims to test whether seal time and energy budgets are altered in the presence of killer whales. So far, the project can address this using existing data from collaborators, namely SMRU telemetry data and killer whale sightings from the public. In the future, such an observational approach could be supplemented by controlled playbacks of killer whale sounds to seals in the wild.
Approach 2 aims to conduct behavioral observations of seal feeding killer whales, in order to estimate hunting effort and number of seals affected. We will conduct preliminary field work this summer to test the feasibility of land-based data collection. We also welcome anyone that is spending time watching killer whales on land, to document what they see in our focal follow form. You can enter it online, or print out a form to fill it on the field. Remember to send the paper back though, by emailing a scan/picture or posting.
Approach 3 aims to monitor the acoustic environment and predator-prey sound production in key areas where interactions are expected to occur. This will be achieved by using data from existing acoustic recorders, and deploying new hydrohones that can be left to record in a station for a couple of months at a time. Killer whales in Shetland have been recorded to produce pulsed calls, echolocation clicks and whistles, but they may be more quiet when hunting for seals. Harbour seal males, on the other hand, produce breeding calls to attract mates, which may also attract killer whales.