Although animal population dynamics have often been correlated with fluctuations in precipitation, causal relationships have rarely been demonstrated in wild birds. We combined nest observations with a field experiment to investigate the direct effect of rainfall on survival of peregrine falcon (Falco peregrinus) nestlings in the Canadian Arctic. We then used historical data to evaluate if recent changes in the precipitation regime could explain the long-term decline of falcon annual productivity. Rainfall directly caused more than one-third of the recorded nestling mortalities. Juveniles were especially affected by heavy rainstorms (≥8 mm/day). Nestlings sheltered from rainfall by a nest box had significantly higher survival rates. We found that the increase in the frequency of heavy rain over the last three decades is likely an important factor explaining the recent decline in falcon nestling survival rates, and hence the decrease in annual breeding productivity of the population. Our study is among the first experimental demonstrations of the direct link between rainfall and survival in wild birds, and clearly indicates that top arctic predators can be significantly impacted by changes in precipitation regime.

Découvrir la revue Citer cet article Jaffré, M., Franke, A., Anctil, A., Galipeau, P., Hedlin, E., Lamarre, V., L'Hérault, V., Nikolaiczuk, L., Peck, K., Robinson, B. & Bêty, J. (2015). Écologie de la reproduction du faucon pèlerin au Nunavut. Le Naturaliste canadien, 139(1), 54-64. doi:10.7202/1027671ar Résumé de l'article Le déclin historique du faucon pèlerin (Falco peregrinus) observé en Amérique du Nord au milieu du xxe siècle a été principalement attribué à l'échec de reproduction causé par les polluants organochlorés persistants. C'est dans ce contexte que le Arctic Raptor Project a été initié, en 1982, dans le but d'étudier la reproduction de faucons pèlerins F.p. tundrius nichant dans l'Arctique. Nous présentons ici une synthèse des principaux travaux conduits dans le cadre de ce programme de recherche réalisé essentiellement dans la région de Rankin Inlet, mais aussi plus récemment près d'Igloolik et sur l'île de Baffin au Nunavut. Des résultats portant sur le régime alimentaire, la phénologie de la reproduction, la croissance et la survie des jeunes, ainsi que sur la dynamique de population sont présentés. Le suivi à long terme dans la région de Rankin Inlet a permis de mettre en lumière, entre autres, une baisse du nombre de jeunes au cours des 3 dernières décennies. Des épisodes de fortes précipitations estivales, plus fréquents dans l'aire d'étude ces dernières années, semblent en partie responsables de ces diminutions. En outre, l'étude des rapaces nichant dans l'Arctique est cruciale pour comprendre les conséquences sur la dynamique des populations, notamment des changements climatiques, de l'environnement (p. ex. diminution des polluants organochlorés) et de la structure et du fonctionnement de l'écosystème arctique. AbstractThe historical decline of the peregrine falcon (Falco peregrinus) in North America during the 20t h century was mainly attributed to reproductive failure due to the accumulation of persistent organochloride pollutants. As a direct result to this finding, the Arctic Raptor Project was established in 1982, and its goal was to monitor the breeding success of Arcticnesting peregrine falcons (F.p. tundrius). The present article provides a synopsis of the major findings of its research, which was principally conducted around Rankin Inlet (Nunavut), but also, more recently, around Igloolik and on Baffin Island (Nunavut). The results cover raptor feeding regimes, reproductive phenology, growth and survival of young, and population dynamics. The long-term Rankin Inlet study has identified, among other things, a decrease in the number of young fledged over the past 3 decades. Episodes of heavy summer rain, which have occurred more frequently in recent years, appear, in part, to be responsible for this decline in reproductive output. The continued study of Arctic-nesting raptors is crucial to our understanding of population dynamics, including how these are affected by changes in climate and in the environment (e.g., reductions in organochloride pollutant levels), and on the stru...

ABSTRACT. We describe an observation of post-fledging double nest switching and alloparenting in the Peregrine Falcon (Falco peregrinus tundrius). During the summer of 2010, a 36-day-old male Peregrine Falcon that had been marked with leg bands was seen flying from its natal site and was subsequently observed at a neighboring nest site that contained two nestlings. Motion-sensitive camera images indicated that the adopted nestling remained at the neighboring site for several days, during which time it shared the nest ledge with the two resident nestlings and was fed by the adults that occupied the site. The juvenile falcon subsequently returned to its natal site, where it shared the nest ledge with its natural sibling and received care from its natural parents. This note is the first documentation of nest switching in wild Peregrine Falcons.

ABSTRACT.-One of the many challenges that climate change researchers are facing is predicting how animal populations may respond to changes in environmental conditions. Changes in climatic patterns may affect populations directly (e.g., influencing thermoregulation of individuals) or indirectly (e.g., influencing food availability). We investigated how those two types of effects affected the growth and survival of Peregrine Falcon (Falco peregrinus) nestlings in the Arctic.Our study area is located on the west shore of Hudson Bay, around the community of Rankin Inlet, Nunavut (62°N, 92°W), where the average summer temperature increased by approximately 1.5 degrees between 1982 and 2009. Here, a long-term studied Peregrine Falcon population shows a highly variable annual productivity that seems to be correlated with the amount of summer precipitation. To examine the effect of precipitation on the growth and survival of the young Peregrine Falcons, we used a combination of nest boxes, automatic scouting cameras and portable weather stations. During the summers of 2009 and 2010, we systematically followed 34 nests, on 12 of which we deployed nest boxes, hence protecting the chicks from the rain and the wind. We then followed chick survival and growth rate at protected sites and unprotected sites. Cameras allowed us to determine changes in food delivery from the parents during storms as well as to determine the causes of mortality of the chicks.Preliminary results show that chicks raised at protected sites tended to survive better than chicks at unprotected sites. However, the growth rate of the surviving chicks did not seem to be affected. The cameras showed that food delivery diminished (sometimes by half) during extended periods of rain. These results indicate that both the direct and indirect effects of weather can strongly affect the condition of the young Peregrine Falcons. An understanding of how changes in weather, like an increase in precipitation, can affect animal populations is critical. These findings provide insight into the influence of changing weather pattern on arctic-nesting Peregrine Falcons.