A growing theme in animal behaviour research is the study of animal personality. Studying personality in animals may at first sound slightly counterintuitive, if not unscientific, but the term simply refers to different individuals of the same species showing consistent differences in their behaviour. By this definition, everyone with a pet has witnessed personality differences in action: just as with people, some birds are smarter than other birds; some fish are more aggressive than other fish; some dogs are more sociable than other dogs.
Personality differences have now been shown in an astounding range of species, from sea anemones, to sheep, to spiders. What’s more interesting is the consequences of these behavioural differences. Just as with humans, the way we behave has consequences for the way we live our lives: the other individuals we associate with, the decisions we make, the way our relationships go are all influenced by our behaviour, and the same can be said for animals. Personality differences in non-human species have been linked to an individual animal’s probability of engaging in fights, their faithfulness to their partner, the effort they invest in raising offspring, their risk of being predated… in short, all things that influence their likelihood of reproducing and surviving. As a result, considering these individual differences is increasingly being recognised as important in animal conservation.
Research into Animal Personalities
My research looks at personality differences in seabird species, and how an individual’s behaviour relates to its success. Seabirds are among the most threatened group of animals on the planet, and to understand why seabird populations are crashing it can be helpful to start from the bottom up: why are some individuals failing to raise chicks successfully, and does this relate to their behaviour?
This summer I travelled to Svalbard to work with one of my study species, the black-legged kittiwake. The kittiwake is a small gull found breeding on coastal cliffs are across the northern hemisphere. Globally, kittiwake populations are in decline, but as with many species, it’s in extreme environments that the birds are particularly suffering. I’m studying kittiwakes breeding in the Arctic, in the Norwegian Archipelago of Svalbard, to see whether personality differences are related to a bird’s reproductive success, and how these this relationship manifests.
I wanted to know more about how an individual’s personality relates to what they do when foraging at sea, and with how successful they are at breeding. But studying animals with such enormous ranges, who spend much of their time out at sea, doesn’t come without challenges. I had some miniature GPS loggers, which, attached to the birds’ feathers, collect data on their movements. However, the loggers could only provide a short snapshot of information into the birds’ behaviour relative to the field season, as they are limited by battery life and issues with staying-on-the-bird. An even greater limit here is the stress caused to the birds by the loggers: they’re very small (within the recommended weight limit for a kittiwake), but reducing any potential source of stress is paramount. I could use a ladder to climb up to nests and check an individual’s breeding success (number of eggs, or chicks, still present). This too comes with the significant issue of the stress caused to the birds by me disturbing them frequently enough to get substantial data on breeding success.
Time-lapse Photography of Seabirds
Time-lapse photography is increasingly used as a tool to monitoring behaviour of seabirds, and I decided to apply it to the kittiwake colonies with the hope that it could kill two birds with one stone (not a pun), and provide me with data on at-sea foraging and nest success. I contacted Dr Dave Butler from Perdix Wildlife Supplies, who set me up with a Reconyx Hyperfire trail camera.
The technique works like this: with the camera fixed firmly in place focused on the nests at the colony, I set it to take one photo every 5 minutes. Using a technique called overlay analysis, every image captured in the season – all 13,692 of them – can be layered on top of one another, resulting in a white blob representing each kittiwake on its nest. Some blobs are fainter than others, though: because the kittiwake wasn’t there for as long. Layering the images on top of one another in varying chunks of time can therefore be used to see when a bird stopped being at a nest – or when that nest failed.
To know how long birds forage for at sea, an extra step is needed to be able to tell the male and female of each nest apart. I used cattle markers to colour the heads of both members of each pair a different colour. The colour lasts well during the breeding season but fades with time, and of course, is non- toxic and non-harmful to the birds – they just look a bit punky for the summer. The same technique of photo layering can then be used to split apart the foraging trips of birds, seeing when one parent left and came back from a trip.
Analysing My Photo Data
Next steps are to analyse the photo data, and see whether birds of different personality differ in how long they forage for, and their ability to raise chicks. Being able to collect this detailed data on the birds 24 hours a day, 7 days a week, whilst hugely minimising unnecessary disturbance was a huge advantage this season, both to us fieldworkers and to the birds.
I’m hugely grateful to Dave Butler and Perdix for their support with this work and enabling me to closely monitor a threatened species and reduce the impact of doing so.
This blog post was written by Stephanie Harris, a PhD candidate at Liverpool University.