A bird’s “personality,” and whether it tends to go with the flow or fight change, could determine how well it will cope with global warming.

That’s according to the latest research from scientist John Cockrem, who is studying whether birds that react to stress with fear could be better at handling climate change than avians apt to fight.

Cockrem, a research scientist at Massey University in Palmerston North, New Zealand, studied the country’s native little penguins to determine if a bird’s individual personality affects how it responds to different stress levels.

When stressed by an outside force, little penguins secrete the hormone corticosterone. Cockrem said all birds have been found to secrete corticosterone when stressed or threatened, while mammals and fish secrete cortisol when threatened.

Corticosterone stimulates a bird’s adrenal gland, helping it adjust to and cope with changes in the environment.

“The secretion of these hormones increases within minutes once an animal perceives a threat, and there is great variation between animals in the size of these responses,” Cockrem said in an email.

Cockrem examined a number of bird species in a 2013 study and discovered that when birds were captured—an obviously stressful situation—some secreted more than 15 times the amount of corticosterone secreted by other birds subjected to the same capture.

By discovering the different ways members of a species react to stress, Cockrem was able to identify a bird’s personality.

Cockrem started investigating whether birds’ personalities will affect their ability to cope with climate change. Scientists have studied the little penguins in Oamaru, on New Zealand’s South Island, for years and collected long-term data on individual penguins' breeding productivity.

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Armed with that information, Cockrem hopes to determine if penguins' breeding productivity differs in response to changes in their environment, such as higher temperatures, drought, or food-source scarcity.

“Birds with proactive personalities are likely to be more successful in constant or predictable conditions, whilst birds with reactive personalities and high corticosterone responses will be more successful in changing or unpredictable conditions,” Cockrem wrote in an abstract he presented to a meeting of the American Physiological Society in San Diego on Oct. 8.

The assumption is that birds with high stress levels will react more quickly to a changing world, and that could improve their chances of successfully coping with global warming. Less fearful, more proactive birds are more likely to fight against change, making them less likely to survive.

“If we find that some species of animals have glucocorticoid responses that change more, or change less, when the animals face environmental challenges that they have not faced before (for example, increased water temperature for fish), and can work out for a species which sort of change is best, then we may be able to use the responses to indicate which species may cope better,” Cockrem said.

The complete study will be published in January in the APS publication The Physiologist.

Such data would be helpful in determining which bird species might be more or less susceptible to climate change. A National Audubon Society study released in September found that half of North American bird species are at risk because of rising temperatures.