Precipitation and ectoparasitism reduce reproductive success in an arctic-nesting top-predator

Abstract

Indirect impacts of climate change, mediated by new species interactions (including pathogens or parasites) will likely be key drivers of biodiversity reorganization. In addition, direct effects of extreme weather events remain understudied. Simultaneous investigation of the significance of ectoparasites on host populations and extreme weather events is lacking, especially in the Arctic. Here we document the consequences of recent black fly outbreaks and extreme precipitation events on the reproductive output of an arctic top predator, the peregrine falcon (Falco peregrinus tundrius) nesting at the northern range limit of ornithophilic black flies in Nunavut, Canada. Overall, black fly outbreaks and heavy rain reduced annual nestling survival by up to 30% and 50% respectively. High mortality caused by ectoparasites followed record-breaking spring snow precipitation, which likely increased stream discharge and nutrient runoff, two key parameters involved in growth and survival of black fly larvae. Using the RCP4.5 intermediate climate scenario run under the Canadian Global Climate Model, we anticipate a northward expansion of black fly distribution in Arctic regions. Our case study demonstrates that, in the context of climate change, extreme weather events can have substantial direct and indirect effects on reproductive output of an arctic top-predator population.

The role of atmospheric circulation patterns in driving recent changes in indices of extreme seasonal precipitation across Arctic Fennoscandia

“…Similar impacts of ground ice on reindeer mortality have been reported (Hansen et al 2014). EPEs during the nesting season can significantly impact the breeding success of birds (Yannic et al 2014;Lamarre et al 2018).…”

Direct and indirect effects of regional and local climatic factors on trophic interactions in the Arctic tundra

“…While most climate change‐related studies primarily focus on measuring the response of organisms to temperature increase, we are only starting to examine the consequences of changes in rainfall on vital rates of animals. Most results point to negative effects of rainfall on reproduction via increased risks of young mortality and foraging cost for parents (Lamarre et al, ; Öberg et al, ).…”

“…Hansen et al, ). Despite the paucity of studies, some have already reported contrasting impacts of various climatic factors on species dynamics in various regions of the Arctic, from positive (geese: Jensen et al, ; Lecomte, Gauthier, & Giroux, ) to negative (geese: Doiron, Gauthier, & Lévesque, ; raptors: Lamarre et al, ; lemming: Ims, Henden, & Killengreen, ). At the ecosystem level, Legagneux et al () showed that warmer temperatures in the Arctic could increase predation intensity on herbivore prey.…”

Nest boxes buffer the effects of climate on breeding performance in an African urban raptor

“…The impact of weather events on peregrine breeding performance has furthermore been documented in several populations, including on the Cape Peninsula, which usually exhibit reduced breeding success when experiencing high rainfall while incubating in spring and early summer [42][43][44][45][46][47][48][49]. Additionally, in the Arctic, a study showed that the increased frequency of heavy rain explained the recent decline in peregrine breeding productivity, most likely in combination with ectoparasite outbreaks [49], and demonstrated experimentally that nestling survival can be improved by the provision of nest boxes [42].…”