Agreement on the Conservation of Albatrosses and Petrels

Non-breeding Wandering Albatrosses forage less successfully as they age, leading to reduced breeding success

Thomas Clay (British Antarctic Survey, Cambridge, United Kingdom) and colleagues have published early view in the journal Functional Ecology on the effects of senescence on foraging and breeding in Vulnerable Wandering Albatrosses Diomedea exulans.

The paper’s abstract follows:

“1. Senescence has been widely documented in wild vertebrate populations, yet the proximate drivers of agerelated declines in breeding success, including allocation tradeoffs and links with foraging performance, are poorly understood. For longlived, migratory species, the nonbreeding period represents a critical time for investment in selfmaintenance and restoration of body condition, which in many species is linked to fitness. However, the relationships between age, nonbreeding foraging behaviour and fitness remain largely unexplored.

2. We performed a crosssectional study, investigating agerelated variation in the foraging activity, distribution and diet of an extremely longlived seabird, the wandering albatross Diomedea exulans, during the nonbreeding period. Eightytwo adults aged 8 – 33 years were tracked with geolocatorimmersion loggers, and body feathers were sampled for stable isotope analysis. We tested for variation in metrics of foraging behaviour, and linked agerelated trends to subsequent reproductive performance.

3. There was an agerelated decline in the number of landings (a proxy of foraging effort) during daylight hours, and a decrease in body feather δ13C values in older males but not females, yet this did not accompany an agerelated shift in distributions. Males conducted fewer landings than females, and the sexes showed some spatial segregation, with males foraging further south, likely due to their differential utilization of winds.

4. Although younger (< 20 years) birds had higher foraging effort, they all went on to breed successfully the following season. In contrast, among older (20+ years) birds, individuals that landed more often were more likely to defer breeding or fail during incubation, suggesting they have lower foraging success.

5. As far as we are aware, this is the first demonstration of an agespecific carryover effect of foraging behaviour in the nonbreeding period on subsequent reproductive performance. This link between foraging behaviour and fitness in late but not early adulthood indicates that the ability of individuals to forage efficiently outside the breeding period may be an important driver of fitness differences in old age.”

 

Wandering Albatross, photograph by John Chardine

With thanks to Richard Phillips.

Reference:

Clay, T.C., Pearmain, E.J., McGill, R.A.R., Manica, A. & Phillips, R.A. 2018.  Age-related variation in non-breeding foraging behaviour and carry-over effects on fitness in an extremely long-lived bird. Functional Ecology doi.org/10.1111/1365-2435.13120.

John Cooper, ACAP Information Officer, 23 April 2018

DMC Firewall is developed by Dean Marshall Consultancy Ltd