Understanding seal behaviour
(1 February 2018)
Dr Sean Twiss has been studying seal behaviour for 30 years and has recently featured on the BBC’s Winterwatch programme. Here Dr Twiss, of the Department of Biosciences, tells us more about his latest research and why seals are as individual as we are.
Tell us about your research into seal behaviour.
My research looks at individual differences in seal behaviour, to help further our understanding of why some seals are more successful than others. Our previous work has shown that seals have very individual ways of behaving and our current research is using heart rate monitoring to see how these behavioural differences are reflected physiologically.
Our study has observed a colony of seals on the Isle of May, off the east coast of Scotland, during the breeding season over the last five years. We have focused our study on female seals whilst they are on land raising their pups.
We used specially adapted heart rate monitors to gain an insight into heart rate patterns and variations both when the seals were in a relaxed state and when exposed to stress. The stress triggers were both natural, for example unwanted proximity or attention from other seals, and artificial. For the artificial stress trigger we used a remote controlled car to approach the seals with a mild auditory stressor (a wolf call) to see how different seals reacted to the same stress trigger.
What have you found through this research?
Over the five years of our study we have seen that individual seals behave and react consistently differently, showing a range of behaviours including confidence, shyness, reactivity and proactivity that are linked to individual differences in their physiological responses.
In some ways this goes against the accepted wisdom that natural selection should drive all individuals towards one optimal type, to overcome the problems that the natural world presents. Through our study, seals are demonstrating that there is not one single solution, but rather a whole range of solutions, to the challenges they face.
We have also found that the behavioural response of seals to stressful events does not entirely reflect their physiological response. Whilst a seal might return to a resting behavioural state fairly swiftly after a stressful event, we found that their heart rate could remain elevated for quite some time afterwards. Seals are driven to conserve energy, particularly during the breeding season, in order to provide fat-rich milk for their pup, so an elevated heart rate will still incur extra energetic cost. Understanding these physiological, as well as behavioural, responses to stress can provide an important additional consideration in assessments of the impacts of wildlife-human interactions, for example for ecotourism.
Finally, we also observed that the physiological responses seals had to anthropogenic (human) disturbances were actually no greater than to natural disturbances. People worry a lot about human disturbance of breeding colonies but our research reminds us that, even for seals, life is naturally stressful. Natural selection is all about how individuals cope with the day to day stresses of surviving and reproducing. The question therefore becomes not whether each seal has the mechanisms or not to cope with stress, but rather whether those mechanisms can cope with the additional stress that human activities can result in.
What are the next steps in your research?
This current research programme is drawing to a close however I would like to explore the opportunities to monitor some of the individual seals at sea to look at how their individual behavioural and physiological types may be reflected in their foraging tactics. For example whether bolder individuals travel further afield to find their food.
I am also interested in applying some of the techniques from this research to sheep populations in Upper Teesdale in the North East of England to understand how individuality amongst sheep influences their grazing patterns.
Dr Sean Twiss has conducted his research in partnership with the Sea Mammal Research Unit, University of St Andrews. You can watch the BBC Winterwatch programme featuring Dr Twiss’s research here (starts at 43:24).