A circumpolar study unveils a positive non-linear effect oftemperature on arctic arthropod availability that may reduce therisk of warming-induced trophic mismatch for breeding shorebirds

Abstract

Seasonally abundant arthropods are a crucial food source for many migratorybirds that breed in the Arctic. In cold environments, the growth and emergence ofarthropods are particularly tied to temperature. Thus, the phenology of arthropodsis anticipated to undergo a rapid change in response to a warming climate, potentiallyleading to a trophic mismatch between migratory insectivorous birds and their prey.Using data from 19 sites spanning a wide temperature gradient from the Subarcticto the High Arctic, we investigated the effects of temperature on the phenology andbiomass of arthropods available to shorebirds during their short breeding seasonat high latitudes. We hypothesized that prolonged exposure to warmer summertemperatures would generate earlier peaks in arthropod biomass, as well as higherpeak and seasonal biomass. Across the temperature gradient encompassed by ourstudy sites (>10°C in average summer temperatures), we found a 3-day shift inaverage peak date for every increment of 80 cumulative thawing degree-days.Interestingly, we found a linear relationship between temperature and arthropodbiomass only below temperature thresholds. Higher temperatures were associatedwith higher peak and seasonal biomass below 106 and 177 cumulative thawingdegree-days, respectively, between June 5 and July 15. Beyond these thresholds,no relationship was observed between temperature and arthropod biomass. Ourresults suggest that prolonged exposure to elevated temperatures can positivelyinfluence prey availability for some arctic birds. This positive effect could, in part,stem from changes in arthropod assemblages and may reduce the risk of trophicmismatch. Sarctic arthropods, arctic breeding shorebirds, climate warming, insectivorous birds,invertebrate biomass, phenology, trophic mismatc