COS 157-5 - Warming in the land of the midnight sun: breeding birds may suffer greater heat stress at high- vs low-Arctic sites

Wednesday, August 17, 2022

11:00 AM – 11:15 AM EDT

Location: 518B

Coauthor(s)

RO

Ryan O'Connor

Université du Québec à Rimouski, Canada
AL

Audrey Le Pogam

Université du Québec à Rimouski, Canada
KY

Kevin Young

Western University, Canada

Presenting Author(s)

OL

Oliver P. Love

University of Windsor, Canada

Coauthor(s)

CC

Christopher Cox

National Oceanic and Atmospheric Administration, United States
GR

Gabrielle Roy

Université du Québec à Rimouski, Canada
FR

Francis Robitaille

Université du Québec à Rimouski, Canada
KE

Kyle Elliott

Professor
McGill University, Canada, Canada
AH

Anna Hargreaves

McGill University, Canada
EC

Emily Choy

McGill University, Canada
GG

Grant Gilchrist

Environment and Climate Change Canada, Canada
DB

Dominique Berteaux

Universite du Quebec a Rimouski, Canada
AT

Andrew Tam

Department of National Defence, Canada
FV

François Vézina

Université du Québec à Rimouski, Canada

Background/Question/Methods

Rising global temperatures are expected to increase reproductive costs for wildlife as greater thermoregulatory demands interfere with reproductive activities. However, predicting the environmental temperatures at which reproductive performance will be negatively impacted remains a significant hurdle. Using a thermoregulatory polygon approach, we derived a reproductive threshold temperature for an Arctic songbird the snow bunting (Plectrophenax nivalis). We defined this threshold as the temperature at which individuals must reduce activity to suboptimal levels (i.e., < 4-times basal metabolic rate) to sustain nestling provisioning and avoid overheating. We then compared this threshold to operative temperatures recorded at high (82°N) and low (64°N) Arctic breeding sites to estimate how heat constraints translate into site-specific impacts on sustained activity level.

Results/Conclusions

The thermal polygon model predicts that buntings will become behaviourally constrained at operative temperatures above 11.7°C, whereupon they must make behavioural adjustments such as reducing provisioning rates to avoid overheating. Low Arctic sites had larger fluctuations in solar radiation, consistently producing daily periods when operative temperatures exceeded 11.7°C. However, whereas the low latitude site showed predictable periods of the day where activity would need to be reduced, the model revealed that birds at the high-latitude site would face entire, consecutive days when parents would be unable to sustain required provisioning rates. These data indicate that Arctic warming is likely already disrupting the breeding performance of cold-specialist birds, but further suggests counterintuitive and severe negative impacts of warming at higher-latitude breeding locations.