Linking demographic processes and foraging ecology in wandering albatross-Conservation implications
Résumé
1. Population dynamics and foraging ecology are two fields of the population ecology that are generally studied separately. Yet, foraging determines allocation processes and therefore demography. Studies on wandering albatrosses Diomedea exulans over the past 50 years have contributed to better understand the links between population dynamics and foraging ecology. This article reviews how these two facets of population ecology have been combined to better understand ecological processes, but also have contributed fundamentally for the conservation of this long-lived threatened species.
2. Wandering albatross research has combined a 50-year long-term study of marked individuals with two decades of tracking studies that have been initiated on this species, favoured by its large size and tameness.
3. At all stages of their life history, the body mass of individuals plays a central role in allocation processes, in particular in influencing adult and juvenile survival, decisions to recruit into the population or to invest into provisioning the offspring or into maintenance.
4. Strong age-related variations in demographic parameters are observed and are linked to age-related differences in foraging distribution and efficiency. Marked sex-specific differences in foraging distribution, foraging efficiency and changes in mass over lifetime are directly related to the strong sex-specific investment in breeding and survival trajectories of the two sexes, with body mass playing a pivotal role especially in males.
5. Long-term study has allowed determining the sex-specific and age-specific demographic causes of population decline, and the tracking studies have been able to derive where and how these impacts occur, in particular the role of long-line fisheries.