One of the reason’s we are monitoring heart rate of individual seals here on the Isle of May is to find out how they deal with stress. A seal’s time on a breeding colony has many potential stressors – aggression from neighbouring mothers, risk of losing your pup, errant males charging around, and so on. All of these stresses are essentially natural – part and parcel of being a seal on a breeding colony, and by and large seals have adapted to cope with these stresses. But, through monitoring heart rate and changes in heart rate measures when seals become involved in these stressful events, we hope to find out which are the most stressful situations for a seal.
What is more, our previous work has shown that there are distinct behavioural types (or ‘personalities’ ) among grey seals, and we are interested in whether these different behavioural types also differ in their ability to cope with these stresses.
That’s where Rocky comes in, using a remotely controlled vehicle allows us to present each of our study seals with a standardised stimulus – we use a wolf call, which generally provokes a mild and temporary increase in vigilance behaviours, with responses varying from an mild increase in pup checking behaviour (the seal turns to look at her pup and make sure it is OK), to absolutely no response at all. Some mums just sleep through the whole thing! At the other extreme, a few mums attack Rocky, and lunge at him. Makes for some fun images from the on board video camera! Anyway, what is really interesting, is that each individual seal, whether nonchalantly ignoring Rocky, or checking on her pup, or trying the chew Rocky’s tyres off, show the same response each time we test the mums – that is, their responses are a consistent part of their personalities.
This year, we are combining these Rocky tests with our heart rate monitors, so we can see who is most stressed – is it the aggressive mums, or is it the ‘pup-checkers’, or maybe even the mums that ignore Rocky? By finding this out, we can see how individuals vary in their stress coping abilities, and so make predictions about how different types of individuals might respond to human disturbance for example, or changing densities of seals on a colony over time, or changing weather patterns – all factors which can alter the types of stressors these seals are exposed to.