Climate‐driven carry‐over effects negatively influence population growth rate in a food‐caching boreal passerine

Abstract

Understanding how events throughout the annual cycle are linked is important for predicting variation in individual fitness, but whether and how carry‐over effects scale up to influence population dynamics is poorly understood. Using 38 years of demographic data from Algonquin Provincial Park, Ontario, and a full annual cycle integrated population model, we examined the influence of environmental conditions and density on the population growth rate of Canada jays (Perisoreus canadensis), a resident boreal passerine that relies on perishable cached food for over‐winter survival and late‐winter breeding. Our results demonstrate that fall environmental variables, most notably the number of freeze–thaw events, carried over to influence late‐winter fecundity, which, in turn, was the main vital rate driving population growth. These results are consistent with the hypothesis that warmer and more variable fall conditions accelerate the degradation of perishable stored food that is relied upon for successful reproduction. Future warming during the fall and winter may compromise the viability of cached food that requires consistent subzero temperatures for effective preservation, potentially exacerbating climate‐driven carry‐over effects that impact long‐term population dynamics.

An observational analysis of Canada Jay (Perisoreus canadensis) foraging and caching ecology in Denali National Park and Preserve, Alaska, USA

“…It is interesting that jay productivity trended upward from 2018 to 2019, given the unusually warm temperatures and lack of snowpack during our autumn 2018 and spring 2019 field seasons. Previous studies examining the influence of freeze-thaw events have found a negative correlation with fecundity (Sutton et al 2019;Sutton et al 2021). Of course, our observations were not of multiple freeze thaw events, but rather delays or accelerations of seasonal temperature and snowpack changes.…”

Investigating factors that set the lower elevational limit of Canada Jays (Perisoreus canadensis) on Vancouver Island, British Columbia, Canada

“…Notwithstanding this putative protection of cached food, the Algonquin study population has decreased by more than 50% since the 1970s (Waite and Strickland 2006;Strickland et al 2011;Sutton et al 2021). There has been no detected change in forest composition over this same time period, but correlational and experimental evidence supports the hypothesis that this decline has been caused by increases in fall temperatures (Waite and Strickland 2006) and/or an increase in the number of freeze-thaw events (Sutton et al 2019).…”

“…There has been no detected change in forest composition over this same time period, but correlational and experimental evidence supports the hypothesis that this decline has been caused by increases in fall temperatures (Waite and Strickland 2006) and/or an increase in the number of freeze-thaw events (Sutton et al 2019). These climatic changes likely accelerate the degradation of cached food (Sechley et al 2015), leading to lower-than-average reproductive success (Waite and Strickland 2006;Sutton et al 2019) and negative population growth rates (Sutton et al 2021). The general finding from the Algonquin Park studies is that the preservation of perishable food stores and hence the demographic fortunes of the park's range-edge Canada jays, benefit from the antimicrobial properties of spruce spp.…”

Breeding dispersal in a resident boreal passerine can lead to short‐ and long‐term fitness benefits

“…In APP, an individually marked population of Canada jays located along the APP's highway 60 corridor has been monitored since 1964 with data on reproductive performance and survival collected annually (Fig. 1; Rutter 1969, Strickland and Waite 2001, Derbyshire et al 2015, Sutton et al 2021a). The study area covers an east-west distance of approximately 55 km and extended a maximum distance of 8 km north or south of the highway 60 corridor.…”

“…Being perishable, food cached by Canada jays is susceptible to degradation over time, especially when exposed to warm temperatures during normally belowfreezing periods (Sutton et al 2019). This degradation of perishable cached food causes Canada jays to experience lower reproductive success when the fall and winter preceding the breeding season has had warmer temperatures and/or more freeze-thaw events than normal (Waite and Strickland 2006, Sutton et al 2019, 2021a.…”