Detecting population heterogeneity in effects of North Atlantic Oscillations on seabird body condition: get into the rhythm

Abstract

Climatic influences on animal populations, mediated by changes in condition‐dependent survival or reproduction, have long intrigued ecologists. We analyzed links between winter North Atlantic Oscillations (NAO), a large scale climatic phenomenon affecting weather conditions over the North Atlantic and the Arctic, and average pre‐laying body mass in common eiders. Body mass is a good proxy for condition‐dependent reproductive output in this species. Time series links were assessed for two eider populations breeding at high latitudes, over a 10‐ and a 21‐year time series. Winter NAO affected body mass in both populations and these effects were easier to detect when changes in the series rhythm were assessed using a novel method based on data discretization and information theory, rather than detection based on changes in amplitude, assessed using traditional linear models. Winter conditions affected body condition of eiders in both populations. Different mechanisms, however, are likely to be involved in the two populations, one being presumably affected by direct effects of climate and the other by effects through the food chain. Therefore, the same species can respond along different pathways to the same large scale climatic pattern, an important consideration when seeking to understand or manage the response of species to present and future climate change.

Weakening of the subpolar gyre as a key driver of North Atlantic seabird demography: a case study with Brünnich’s guillemots in Svalbard

“…So far, many studies on seabirds breeding around the North Atlantic have demonstrated the influence of the NAO on life history traits and population dynamics (e.g. Wanless et al 2009, Descamps et al 2010, Sandvik et al 2012, Smith & Gaston 2012. As a 'weather package' , the NAO index is assumed to be a reliable proxy for North Atlantic climate, catching most of the variation in several atmospheric and oceanographic parameters (e.g.…”

Long-term monitoring at multiple trophic levels suggests heterogeneity in responses to climate change in the Canadian Arctic tundra

“…In migratory birds, population attributes can be strongly affected by environmental factors encountered away from the Arctic breeding grounds [53,65,66]. Spring migration phenology, and hence timing of breeding, may be constrained by the timing of life-cycle phases preceding migration, by different climatic variations in the wintering areas and along the migratory route, or by depleted genetic variance in migration traits [67].…”

Survival and local recruitment are driven by environmental carry-over effects from the wintering area in a migratory seabird

“…In several bird species, associations of the NAOI with vital rates have already been found (e.g. Forchhammer et al 1998;Grosbois and Thompson 2005;Crespin et al 2006;Descamps et al 2010;Zipkin et al 2010).…”