The shyness of the albatross
b5331072-41f8-4342-958c-83ff4aa941d7
Bold and shy personality differences have been found to be at the root of breeding success in a colony of albatrosses.
Many long-lived birds, like mammals, appear to develop idiosyncratic behavioural differences that are equatable with personalities. These individual differences have now been found to drive different success rates in breeding, a new study has found.
A sub-colony of 200 Black-browed Albatross pairs on Cañon des Sourcils Noirs on the sub-Antarctic Kerguelen Islands (in the French Southern and Antarctic Lands) was studied from December 2011 to January 2012 (part of the southern breeding season), while the birds were incubating and guarding chicks. The species can live for over 50 years – plenty of time to develop behavioural quirks – has low sexual dimorphism and breeds every year in the austral summer. The sub-colony has been monitored since 1979, resulting in good comparable estimates of annual breeding success, recruitment to the colony and survival rates.
Single birds were observed for the personality trait of 'boldness' (in response to a large pink volleyball, chosen as a novelty object and placed adjacent to the nest with minimal environmental variation) and a 'foraging personality score' – birds were tracked by GPS devices to see how many foraging trips they made and how long these were by time and distance.
Individual albatrosses that exhibited greater boldness towards the volleyball generally made shorter trips away from the colony, and foraged on the island's underwater shelf or shelf edge rather than over the open ocean (though boldness did not influence the amount of time spent or likelihood of visiting fishing vessels).
During the 2011 breeding season, bolder birds foraging closer to the sub-colony showed a trend of greater reproductive success. Over the previous years for which data were available, this trend was more noticeable – results were sex-linked and bold females had higher reproductive fitness in years with a higher sea surface temperature than average, while 'shyer' females were more successful during years with a lower than average surface temperature. In males, shy birds always had a higher success rate but this became more prominent in years with a low ocean surface temperature.
The behaviour was consistently repeatable in individuals and so could be called a personality as we understand it, and showed correlation with breeding success. The foraging of shy birds further afield probably helps them avoid competition with the bolder birds. Boldness appears to enable the birds to be more competitive for food in 'boom' years with higher sea surface temperatures. This strategy is less successful in times of bust, though males tend to forage over the open ocean whatever the circumstance and are overall more shy.
These traits are complex, but appear to be crucial in deciding the outcome of foraging and offspring survival. Selection – which controls the evolution of all the heritable and learnt traits of animals – is governed by the seasonal changing of food availability linked to the adaptive benefits of the shy and bold conditions, but each bird needs to be monitored over time to see if personalities correlate with the long-term survival of the individual. The differences between the two sexes and the consequent advantages may also become more apparent when monitored over an entire albatross lifetime.
Reference
Patrick, S C, and Weimerskirch, H. 2014. Personality, Foraging and Fitness consequences in a Long Lived Seabird. PLOSONE 9 (2): e87269.
Many long-lived birds, like mammals, appear to develop idiosyncratic behavioural differences that are equatable with personalities. These individual differences have now been found to drive different success rates in breeding, a new study has found.
A sub-colony of 200 Black-browed Albatross pairs on Cañon des Sourcils Noirs on the sub-Antarctic Kerguelen Islands (in the French Southern and Antarctic Lands) was studied from December 2011 to January 2012 (part of the southern breeding season), while the birds were incubating and guarding chicks. The species can live for over 50 years – plenty of time to develop behavioural quirks – has low sexual dimorphism and breeds every year in the austral summer. The sub-colony has been monitored since 1979, resulting in good comparable estimates of annual breeding success, recruitment to the colony and survival rates.
Single birds were observed for the personality trait of 'boldness' (in response to a large pink volleyball, chosen as a novelty object and placed adjacent to the nest with minimal environmental variation) and a 'foraging personality score' – birds were tracked by GPS devices to see how many foraging trips they made and how long these were by time and distance.
Individual albatrosses that exhibited greater boldness towards the volleyball generally made shorter trips away from the colony, and foraged on the island's underwater shelf or shelf edge rather than over the open ocean (though boldness did not influence the amount of time spent or likelihood of visiting fishing vessels).
During the 2011 breeding season, bolder birds foraging closer to the sub-colony showed a trend of greater reproductive success. Over the previous years for which data were available, this trend was more noticeable – results were sex-linked and bold females had higher reproductive fitness in years with a higher sea surface temperature than average, while 'shyer' females were more successful during years with a lower than average surface temperature. In males, shy birds always had a higher success rate but this became more prominent in years with a low ocean surface temperature.
The behaviour was consistently repeatable in individuals and so could be called a personality as we understand it, and showed correlation with breeding success. The foraging of shy birds further afield probably helps them avoid competition with the bolder birds. Boldness appears to enable the birds to be more competitive for food in 'boom' years with higher sea surface temperatures. This strategy is less successful in times of bust, though males tend to forage over the open ocean whatever the circumstance and are overall more shy.
These traits are complex, but appear to be crucial in deciding the outcome of foraging and offspring survival. Selection – which controls the evolution of all the heritable and learnt traits of animals – is governed by the seasonal changing of food availability linked to the adaptive benefits of the shy and bold conditions, but each bird needs to be monitored over time to see if personalities correlate with the long-term survival of the individual. The differences between the two sexes and the consequent advantages may also become more apparent when monitored over an entire albatross lifetime.
Reference
Patrick, S C, and Weimerskirch, H. 2014. Personality, Foraging and Fitness consequences in a Long Lived Seabird. PLOSONE 9 (2): e87269.
