55 years of bird data reveal climate and predators as dual threats to populations
Swedish researchers tracking a songbird population since 1965 found that warming temperatures and small predator populations both disrupt breeding success—but in different ways. The findings suggest climate change and ecosystem shifts pose compounding risks to wildlife, with implications for how conservation strategies must adapt to multiple stressors.
Originaltitel: Impact of mustelid predation and ambient temperature on breeding success and population dynamics of Pied Flycatchers Ficedula hypoleuca in Swedish Lapland, 1965–2019: [Påverkan av vesslor och temperatur på svartvita flugsnapparens Ficedula hypoleuca häckningsframgång och populationsdynamik i Lappland 1965–2019]
<p>The breeding success of a nest-box breeding population of Pied Flycatcher Ficedula hypoleuca in subalpine birch forest in Swedish Lapland was studied over 55 years, with emphasis on the impact of small mustelids and ambient temperature during egg laying, incubation, and brood care. The proportion of nests predated was used as an index for mustelid abundance. Breeding failures were either total, due to breeding interruptions, or partial due to partial hatching failure or nestling death. Overall, mustelid abundance explained the rate of breeding interruptions at any breeding phase, but not when seasons with exceptional (>10%) predation rates were excluded. Variation in the rate of partial failure was unrelated to mustelid abundance. Climatic conditions affected clutch size, rate of breeding interruption, and partial loss of clutches or broods, with particularly pronounced effects during the incubation period. The mustelid abundance and weather conditions also influenced rates of nest-box occupation in subsequent breeding seasons, and the next-box population dynamics covaried with surrounding populations.</p>