Posted by Tom Bodey

Scientists are always trying to communicate their research and ideas across a wide spectrum of media to varying degrees of success (and I can already feel the hoisting of my own petard here). Some of the difficulties arise because a researcher can apply caution and caveating to their results, whereas recipients may prefer to see a clear-cut outcome that makes for more straightforward decision-taking for example. However, scientists do not always help themselves, either by using jargon, or through the avoidance of terms because of the connotations they may imply.

For my latest research I have decided to enter one of these minefields by looking at individual variation in behavioural responses – you see, I’ve done it myself. This variation, particularly if examined across contexts, has been given a range of names within the scientific literature – behavioural syndromes, coping styles, behavioural tendencies – all of which shy away from the dreaded p word – ‘personality’. Now, of course, there are obvious reasons why a researcher may choose to avoid this word, and certainly to use it within air quotes. After all, without becoming Dr Doolittle, it’s pretty hard to get into a non-human head to actually assess their personality, and what you have instead is the examination of a handful of behaviours where individuals differ in their responses.

Welcome to the office. Rakitu Island study site – you don’t get many laboratories with views like that.

However, even on these highly simplified ‘personality’ scales, it is becoming increasingly obvious that individual animals often differ substantially, and also consistently, in their behaviour. For example, some individuals from species as different as prawns, hyenas and albatross can be bolder, more active, or more social than others, and this variation can then affect other aspects of their lives such as how they find food. These differences are especially intriguing as the maintenance of variation stands in contrast to the movement of species towards a fitness peak. In order to maintain variation, there must be situations in which one set of behaviours are beneficial, and contrasting situations where different individuals prosper – any peak must shift through time or space.

Not content with dipping my toe into an area with such linguistic juggling, I thought I would combine this with invasive species – another area where terminology can take on unfortunately loaded connotations – by looking at individual variation across a range of niche dimensions in everyone’s favourite critter, the humble rat. The Chinese, of course, recognise the rat as the first animal within their zodiac cycle, embodying alertness, spirit and intelligence (as well as being timid, devious and gossipy to balance it out). New Zealand is ‘blessed’ with three species – all invasive and globally widespread – the Brown/Norway Rat Rattus norvegicus, Black/Ship Rat R rattus and the Pacific Rat/Kiore R exulans. I’ve been catching wild rats on offshore islands in the beautiful Hauraki Gulf, running them through behavioural trials in the field before releasing them in order to do it all again the next day, and the next.

Taking pictures of rats in livetraps is tricky. This is a kiore.

Right now I just have a lot of home video, but ultimately this work should provide insights into ecological theory – for example, the ways in which interference competition affects niche space occupancy at individual and species levels. It should also have applied applications for invasive species management. New Zealand, like many oceanic islands, is in the position of having no native terrestrial mammals, and thus can manage invasive mammals, should they choose to do so, in relatively straightforward and robust ways. However, elsewhere management must avoid harming native mammal species. Triaging of the system, making adjustments to maximise the chances of catching the individuals with the greatest potential to cause harm, would be the most cost-effective way forward if eradication is not possible or desirable. And if eradication is the goal, then you need to know there aren’t individuals that will avoid all control mechanisms. Either way, identifying those individuals with a ‘troublemaking personality’ (as any press release might say but any scientific paper would not) is key.