New Publication – Individual aggression in young grey seals

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Working out whether to be nasty or nice to your neighbors is crucial for many species!

Link to article: http://onlinelibrary.wiley.com/doi/10.1111/mms.12367/full

Or read the summary here on this site.

Its that time of year when lots of people at my lab in St Andrews are getting ready for the grey seal breeding season on the Isle of May (IOM16), an important chance for many different projects studying everything from behaviour to physiology to get crucial data or samples. Logistically, getting all the supplies for the science the PHATS team needs to do in the next two months is quite a challenge and I’m currently packing and checking equipment off all sorts of lists to ensure we’ve got everything. Everything for the tissue culture work needs to be sterilised here on the mainland and packaged up carefully so we can get it out to the island in one piece, taking PCR hoods and incubators out on boats can be interesting but we managed fine last year so I’m sure it will all work this year too. We should be heading out to the island in the last week of October (as long as the weather plays ball), and I’ll start posting regular blog updates about what’s happening once we are in the field.

In amongst the ‘organised chaos’ of all the packing, it was great to see that one of my new papers was finally available online for people to read. The work was done as part of my PhD and happened on the Isle of May too, although this study was a purely behavioural one. Its always a relief to get a piece of work published, the process can be long and arduous but ultimately getting your science out there for other people to read is what research is all about. So why study aggression, and why on the seals on the Isle of May? Read on…

Aggression is a vital aspect of an individual’s behaviour in the majority of animal species trying to live in the wild. Being aggressive enables individuals to take things from others that they need to survive or reproduce, such as mates, good quality habitat to live in or things to eat and drink. Conversely, being aggressive also means you can defend yourself, your offspring or members of your social group from attack, or protect your territory or food resources from attack. The ability to gain the best resources to live on, and keep hold of them so you and your offspring benefit from them, is therefore an important one. But as aggression can have high negative costs, such as injury or even death, striking the balance between individuals that aren’t push overs, but don’t get into too much conflict is an interesting evolutionary challenge all species face. There is huge variation in how aggressive different individuals are, and while some of this variation can be attributed to true psychological differences, which only exist in each individual’s head, we wanted to know to what extent physiological or environmental factors impacted on how aggressive individuals are.

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Aggression can enable individuals to protect things that are valuable to them, like their offspring…. (grey seal mothers and pups on the Isle of May, 2015)
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…or aggression can help you fight for the things you need, like access to the lady seals! (male grey seals fighting for access to females, Isle of May, 2011)

There have been many studies on the sources of individual aggression in a variety of species, from humans to insects. However there are not many studies investigating how aggressiveness in individuals develops in the wild (the ontogeny of a trait). As I had previously designed and carried out research documenting aggressive behaviour in the weaned grey seal pups on the Isle of May, it was an ideal place to try and find out more about the individual factors that influence how aggressive individuals are towards each other. We found that pups raised on crowded areas of the colony were more aggressive than pups from areas with few seals, and that physical characteristics (sex and size) also influence how aggressive individuals were. Males got more aggressive the bigger they were, but female size and aggression showed a non-linear relationship, meaning even a small female seal could still be very aggressive towards others!

The social environment you are raised in has been shown to have lifelong impacts on your behaviour, so it would be great to determine whether these aggressive pups from high density areas of the breeding colony stayed that way throughout their entire lives, or whether other factors take over as the individual grows up. The same is true for males and their body size, are these males only aggressive when they are large, and do they become more timid as they lose mass when using up their fat reserves during the moult or breeding season? Lots of questions still to answer, but this study highlights how a few individual features can influence behaviour, and indicates these variables are worth investigating in future work.

 

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