Demographic sensitivity to environmental forcings: a multi‐trait, multi‐colony approach

• Published in: Oikos
• Main Authors: Sauser, Christophe, Delord, Karine, Barbraud, Christophe
• Other Authors: Centre d'Études Biologiques de Chizé - UMR 7372 (CEBC), La Rochelle Université (ULR)-Centre National de la Recherche Scientifique (CNRS)-Institut National de Recherche pour l’Agriculture, l’Alimentation et l’Environnement (INRAE)
• Format: Article in Journal/Newspaper
• Language: English
• Published: HAL CCSD 2021
• Subjects: Antarctic; bottom–up; capture–mark–recapture; demography; elasticity; matrix population model; multi-colony; perturbation analysis; seabirds; sea ice; top–down; [SDE]Environmental Sciences; Nivea; Antarc*; Sea ice; Snow Petrel
• Online Access: https://hal.science/hal-03345273; https://doi.org/10.1111/oik.07441

International audience Understanding the demographic responses of wild animal populations to different factorsis fundamental to make reliable prediction of population dynamics. Both bottom–up processes and top–down regulation operate in terrestrial and marine ecosystems,but their relative contribution remains insufficiently known. In addition, directweather effects on demographic rates have been overlooked in marine ecosystems andinferences on the demographic effects of environmental drivers were overwhelminglymade from single study sites. Here, we evaluate the relative effects of bottom–up,top–down and weather processes on four vital rates and on population growth rates ofa long-lived seabird, the snow petrel Pagodroma nivea, within three different breedingcolonies. We used multistate capture–recapture modelling and perturbation analysesfrom a matrix population model based on a 36-year-long (1981–2017) individualmonitoring dataset to quantify the different drivers (predation, climatic and weathercovariates) of probabilities of survival, breeding, hatching and fledging according tocolony, sex and breeding status of individuals. Results show that bottom–up forces andlocal weather affected breeding parameters, and that survival was driven by top–downregulation pressure and bottom–up processes. Breeding parameters differed betweencolonies and survival was sex-specific. Sensitivity analysis revealed that populationregulation was mainly driven by bottom–up processes and that top–down processesplayed a minor role. However, there were major differences between colonies about theimportance of how local weather processes affected population growth rate. Our studybrings new insights into the drivers of demographic processes in a marine meso-predator,and how these drivers vary according to colonies and individual characteristics.We emphasize the importance of considering multiple study sites to make robust inferenceson the effects of environmental drivers on wildlife demography. More generally,robust conclusions about ...