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

Vincent Lamarre,Dominique Berteaux,Alastair Franke,Douglas C Currie,Nicolas Casajus,Joël Bêty,Pierre Legagneux

doi:10.1038/s41598-018-26131-y

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.

Highlights

Recent climate change has been associated with higher temperatures, and long-term projections indicate that an increase in the frequency of extreme weather events is likely[1]
Arctic species, including parasites and hosts have evolved under limiting environmental conditions and their life history traits are sensitive to even small changes in climatic conditions[28]
Our results confirm that increased frequency of heavy precipitation can reduce reproductive output of arctic-nesting peregrine falcons directly, and indirectly through the outbreak of black flies described here and elsewhere[31]

Summary

Introduction

Recent climate change has been associated with higher temperatures, and long-term projections indicate that an increase in the frequency of extreme weather events is likely[1]. Despite exposure and sensitivity of arctic host-parasite systems to climate change, empirical and model-based studies describing climate impacts on life history traits of parasites[17,18] and fitness consequences on hosts[19] in arctic regions are lacking[7]. This is surprising given that tundra ecosystems comprise low diversity of pathogens and parasites, relatively few species interactions[20], and minimal anthropogenic disturbance, greatly facilitating understanding of the climate-driven mechanisms potentially affecting host-parasite interactions. Our objectives were to: (i) illustrate the potential significance of ornithophilic black fly outbreaks at their northern range limit and heavy rain on nestling mortality in peregrine falcons; (ii) investigate the potential mechanisms (such as changes in temperature, precipitation and snow regimes) involved in promoting local black fly outbreaks and (iii) estimate the northern limit of black fly distribution using climate data (1990–2010) and project shifts in the northern limit using Canadian Global Climate Models with the RCP4.5 scenario[23]

Objectives

Methods

Results

Conclusion