|A European greenfinch (Carduelis chloris) on a garden birdfeeder. Some birds are bolder when feeding than others, reflecting their personalities. Photo courtesy Martin Fowler.
An individual’s personality can have a big effect on his or her life. Some people are outgoing and gregarious while others find novel situations stressful, and this can be detrimental to their health and well-being. Scientists are discovering that animals are no different, displaying distinct personalities.
A study, led by Dr. Kathryn Arnold of the Environment Department at the University of York in England, adds important experimental evidence showing that animal personalities are reflected physically, by measurement of their oxidative stress profiles.
Dr. Arnold teamed up with graduate student Katherine Herborn at the Institute of Biodiversity, Animal Health and Comparative Medicine at the University of Glasgow to classify the personalities of 22 greenfinches.
They tested each bird’s reactions to a novel situation by adding a brightly colored cookie-cutter to each greenfinch’s food bowl, and timing how long it took for the birds to pluck up courage to approach the food. The researchers found that the boldest birds took only a few seconds to overcome their fear, while more timid birds took up to 30 minutes to approach their meal.
Dr. Arnold and Herborn also measured the greenfinches’ motivation to explore by attaching an intriguing object to the birds’ perches and timing how long it took them to land next to it. However, there was no correlation between the birds’ courage and curiosity in this case.
Blood Chemistry Patterns Provide Confirmation
The researchers then measured the birds’ damaging reactive oxygen metabolite levels and their defenses against them. Comparing the bird’s blood oxidative profiles with their personalities, the team found that the most timid birds had the highest levels of damaging oxygen toxins and the weakest defenses, so they suffered more oxidative stress than braver individuals. Also, the scientists observed that the most curious birds, which approached the alien objects faster, had better defenses against oxidative damage than their less-curious companions.
Dr. Arnold wants to extend the work to establish how personality traits affect birds in the wild.
"So-called neophobic birds—those that are afraid of new things—may suffer high costs of oxidative stress and die early because of this physiological impact,” she said. "On the other hand, they might also be less likely to be eaten by a predator because they are more wary than bolder birds.”
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