Divergent population trajectories despite similar response to temperature in a widespread aerial insectivore

C Conor C. Taff (Department of Ecology and Evolutionary Biology and Lab of Ornithology, Cornell University) J J. Ryan Shipley (Department of Fish Ecology and Evolution, Swiss Federal Institute of Aquatic Sciences and Technology) D Daniel R. Ardia (Department of Biology, Franklin & Marshall College) D David Aborn (Department of Biology, Geology, and Environmental Science, University of Tennessee at Chattanooga) L Lauren Albert (Department of Biology, Indiana University) M Marc Bélisle (Département de biologie, Université de Sherbrooke) A Amos Belmaker (Steinhardt Museum of Natural History, Tel Aviv University) L Lisha L. Berzins (Department of Biology, University of Saskatchewan) T Tricia Blake (Alaska Songbird Institute) F Frances Bonier (Department of Biology, Queen’s University) H Hannah C. Brewer (Department of Ecology and Evolutionary Biology, University of Connecticut) M Michael W. Butler (Department of Biology, Lafayette College) K Kyle Cameron (Long Point Bird Observatory, Birds Canada) S Samuel B. Case (Department of Biology, University of Washington) D David Chang van Oordt R Robert G. Clark (Environment and Climate Change Canada, Science and Technology Branch, Wildlife Research Division) E Ethan D. Clotfelter (Department of Biology, Amherst College) A Amelia R. Cox (Cumulative Impact Monitoring Program, Government of Northwest Territories) R Russell D. Dawson (Department of Ecosystem Science and Management, University of Northern British Columbia) E Elizabeth P. Derryberry (Department of Ecology and Evolutionary Biology and Collaborative for Animal Behavior, University of Tennessee) A Ana M. Diaz Bohorquez (Environment and Climate Change Canada, Science and Technology Branch, Wildlife Research Division) P Peter O. Dunn (Department of Biological Sciences, University of Wisconsin–Milwaukee) V Valentina Ferretti (Instituto de Ecología, Genética y Evolución de Buenos Aires, Universidad de Buenos Aires) A Anna M. Forsman (Department of Biology, Colby College) M Matthew Fuirst (Long Point Bird Observatory, Birds Canada) D Dany Garant (Département de biologie, Université de Sherbrooke) D Daniel R. Garrett (Département de biologie, Université de Sherbrooke) J Jessica Gutiérrez (Department of Ecology and Evolutionary Biology, University of Connecticut) J Julie C. Hagelin (Threatened, Endangered and Diversity Program, Alaska Department of Fish and Game) B Braelei M. Hardt (National Wildlife Federation) M Mercy E. Harris (Environment and Climate Change Canada, Science and Technology Branch, Wildlife Research Division) K Kyle Horton (Department of Forestry and Natural Resources, Purdue University) C Carolyne Houle (Département de biologie, Université de Sherbrooke) J Jennifer L. Houtz (Department of Biology, Allegheny College) P Patricia L. Jones (Biology Department, Bowdoin College) K Kimberley C. Jordan (Department of Zoology and Physiology, University of Wyoming) A Amanda S. Kindel (Museum of Wildlife and Fish Biology, University of California–Davis) R Robert Klaver (Department of Natural Resource Ecology and Management, Iowa State University) S Sarah A. Knutie (Department of Ecology and Evolutionary Biology, University of Connecticut) K Katherine S. Lauck (Department of Wildlife, Fish, and Conservation Biology, University of California–Davis) M Michael P. Lombardo (Department of Biology, Grand Valley State University) S Stephen C. Lougheed (Department of Biology, Queen’s University) A Ashley C. Love (Department of Biology, Miami University) S Stuart A. Mackenzie (Long Point Bird Observatory, Birds Canada) J John P. McCarty (Department of Biology, University of Nebraska Omaha) A Ann E. McKellar (Environment and Climate Change Canada, Science and Technology Branch, Wildlife Research Division) N Nicole Mejia (Department of Ecology and Evolutionary Biology and Lab of Ornithology, Cornell University) C Christy A. Morrissey (Department of Biology, University of Saskatchewan) M Mia L. Nahom (Pacific States Marine Fisheries Commission) D D. Ryan Norris (Department of Integrative Biology, University of Guelph) L Lillian M. Para (Department of Ecology and Evolutionary Biology, University of Tennessee) F Fanie Pelletier (Département de biologie, Université de Sherbrooke) C Cody K. Porter (Biology Department, Hope College) W Wallace B. Rendell (School of Applied Sciences Skills and Technology, Loyalist College) E Eric A. Riddell (Department of Biology, University of North Carolina at Chapel Hill) J James W. Rivers (Department of Forest Engineering, Resources, and Management, Oregon State University) R Raleigh J. Robertson (Department of Biology, Queen’s University) A Alexandra Rose (Department of Ecology and Evolutionary Biology, University of Colorado) K Kimberly A. Rosvall (Department of Biology, Indiana University) T Thomas A. Ryan (Department of Ecology and Evolutionary Biology and Lab of Ornithology, Cornell University) R Ryan P. Shannon (Department of Biology, Miami University) D Dave Shutler (Department of Biology, Acadia University) V Victoria F. Simons (Itasca Biological Station and Laboratories, University of Minnesota) M Mark Stanback (Department of Biology, Davidson College) C Corey E. Tarwater (Department of Zoology and Physiology, University of Wyoming) P Patrick A. Thorpe (Department of Biology, Grand Valley State University) M Morgan W. Tingley (Department of Ecology and Evolutionary Biology, University of California) C Christine L. Tischer (Sea and Sage Audubon) B Benjamin A. Tonelli (Department of Biological Sciences, Clemson University) M Melanie L. Truan (Museum of Wildlife and Fish Biology, University of California–Davis) C Cornelia W. Twining (Department of Fish Ecology and Evolution, Swiss Federal Institute of Aquatic Sciences and Technology) J Jennifer J. Uehling (Department of Ecology, Evolution and Organismal Biology, Iowa State University) C Carol Vleck (Department of Biology, West Chester University) D David Vleck (Department of Biology, West Chester University) M Michael L. Watson (The Holden Arboretum) N Nathaniel T. Wheelwright (Biology Department, Bowdoin College) L Linda A. Whittingham (Department of Biological Sciences, University of Wisconsin–Milwaukee) D David W. Winkler (SABER Consulting) C Casey Youngflesh (Department of Biological Sciences, Clemson University) C Cedric Zimmer (Laboratoire d’Ethologie Expérimentale et Comparée, Université Sorbonne Paris Nord) M Maren N. Vitousek (Department of Ecology and Evolutionary Biology and Lab of Ornithology, Cornell University)

Abstract

Climate change is shifting when animals breed [C. Parmesan, G. Yohe, Nature 421 , 37–42 (2003) and S. J. Thackeray et al. , Nature 535 , 241–245 (2016)], but it is not clear why some populations keep pace with warming while others fall behind [L. D. Bailey et al. , Nat. Commun. 13 , 2112 (2022) and J. M. Samplonius et al. , Glob. Change Biol. 24 , 3780–3790 (2018)]. Differences could arise from variation in sensitivity to temperature [L. D. Bailey et al. , Nat. Commun. 13 , 2112 (2022)] or constraints on the ability to respond to temperature. Without knowing whether populations differ in sensitivity—or in their ability to act on that sensitivity—we cannot identify which are most at risk. Using 1,555 population-years from 123 populations of tree swallows ( Tachycineta bicolor ), we show that populations have similar sensitivity to local temperature, advancing breeding by about one day per degree of warming. However, northern populations face tighter time constraints and greater exposure to recent warming. Northern populations have advanced laying dates the most, but still experience stronger selection for earlier breeding, especially in warm years; they have also declined most in breeding abundance. These findings suggest that vulnerability to climate change can arise not just from different sensitivity to warming, but from when and where populations can respond effectively. By disentangling sensitivity from timing constraints, our results are consistent with a general mechanism by which even uniformly responsive species can show uneven impacts of climate change across their ranges.

Article Details

Volume / Issue Vol. 123, Issue 28
Published July 14, 2026
ISSN 0027-8424
Publisher National Academy of Sciences

Authors (81)

C

Conor C. Taff

Department of Ecology and Evolutionary Biology and Lab of Ornithology, Cornell University

J

J. Ryan Shipley

Department of Fish Ecology and Evolution, Swiss Federal Institute of Aquatic Sciences and Technology

D

Daniel R. Ardia

Department of Biology, Franklin & Marshall College

D

David Aborn

Department of Biology, Geology, and Environmental Science, University of Tennessee at Chattanooga

L

Lauren Albert

Department of Biology, Indiana University

M

Marc Bélisle

Département de biologie, Université de Sherbrooke

A

Amos Belmaker

Steinhardt Museum of Natural History, Tel Aviv University

L

Lisha L. Berzins

Department of Biology, University of Saskatchewan

T

Tricia Blake

Alaska Songbird Institute

F

Frances Bonier

Department of Biology, Queen’s University

H

Hannah C. Brewer

Department of Ecology and Evolutionary Biology, University of Connecticut

M

Michael W. Butler

Department of Biology, Lafayette College

K

Kyle Cameron

Long Point Bird Observatory, Birds Canada

S

Samuel B. Case

Department of Biology, University of Washington

D

David Chang van Oordt

R

Robert G. Clark

Environment and Climate Change Canada, Science and Technology Branch, Wildlife Research Division

E

Ethan D. Clotfelter

Department of Biology, Amherst College

A

Amelia R. Cox

Cumulative Impact Monitoring Program, Government of Northwest Territories

R

Russell D. Dawson

Department of Ecosystem Science and Management, University of Northern British Columbia

E

Elizabeth P. Derryberry

Department of Ecology and Evolutionary Biology and Collaborative for Animal Behavior, University of Tennessee

A

Ana M. Diaz Bohorquez

Environment and Climate Change Canada, Science and Technology Branch, Wildlife Research Division

P

Peter O. Dunn

Department of Biological Sciences, University of Wisconsin–Milwaukee

V

Valentina Ferretti

Instituto de Ecología, Genética y Evolución de Buenos Aires, Universidad de Buenos Aires

A

Anna M. Forsman

Department of Biology, Colby College

M

Matthew Fuirst

Long Point Bird Observatory, Birds Canada

D

Dany Garant

Département de biologie, Université de Sherbrooke

D

Daniel R. Garrett

Département de biologie, Université de Sherbrooke

J

Jessica Gutiérrez

Department of Ecology and Evolutionary Biology, University of Connecticut

J

Julie C. Hagelin

Threatened, Endangered and Diversity Program, Alaska Department of Fish and Game

B

Braelei M. Hardt

National Wildlife Federation

M

Mercy E. Harris

Environment and Climate Change Canada, Science and Technology Branch, Wildlife Research Division

K

Kyle Horton

Department of Forestry and Natural Resources, Purdue University

C

Carolyne Houle

Département de biologie, Université de Sherbrooke

J

Jennifer L. Houtz

Department of Biology, Allegheny College

P

Patricia L. Jones

Biology Department, Bowdoin College

K

Kimberley C. Jordan

Department of Zoology and Physiology, University of Wyoming

A

Amanda S. Kindel

Museum of Wildlife and Fish Biology, University of California–Davis

R

Robert Klaver

Department of Natural Resource Ecology and Management, Iowa State University

S

Sarah A. Knutie

Department of Ecology and Evolutionary Biology, University of Connecticut

K

Katherine S. Lauck

Department of Wildlife, Fish, and Conservation Biology, University of California–Davis

M

Michael P. Lombardo

Department of Biology, Grand Valley State University

S

Stephen C. Lougheed

Department of Biology, Queen’s University

A

Ashley C. Love

Department of Biology, Miami University

S

Stuart A. Mackenzie

Long Point Bird Observatory, Birds Canada

J

John P. McCarty

Department of Biology, University of Nebraska Omaha

A

Ann E. McKellar

Environment and Climate Change Canada, Science and Technology Branch, Wildlife Research Division

N

Nicole Mejia

Department of Ecology and Evolutionary Biology and Lab of Ornithology, Cornell University

C

Christy A. Morrissey

Department of Biology, University of Saskatchewan

M

Mia L. Nahom

Pacific States Marine Fisheries Commission

D

D. Ryan Norris

Department of Integrative Biology, University of Guelph

L

Lillian M. Para

Department of Ecology and Evolutionary Biology, University of Tennessee

F

Fanie Pelletier

Département de biologie, Université de Sherbrooke

C

Cody K. Porter

Biology Department, Hope College

W

Wallace B. Rendell

School of Applied Sciences Skills and Technology, Loyalist College

E

Eric A. Riddell

Department of Biology, University of North Carolina at Chapel Hill

J

James W. Rivers

Department of Forest Engineering, Resources, and Management, Oregon State University

R

Raleigh J. Robertson

Department of Biology, Queen’s University

A

Alexandra Rose

Department of Ecology and Evolutionary Biology, University of Colorado

K

Kimberly A. Rosvall

Department of Biology, Indiana University

T

Thomas A. Ryan

Department of Ecology and Evolutionary Biology and Lab of Ornithology, Cornell University

R

Ryan P. Shannon

Department of Biology, Miami University

D

Dave Shutler

Department of Biology, Acadia University

V

Victoria F. Simons

Itasca Biological Station and Laboratories, University of Minnesota

M

Mark Stanback

Department of Biology, Davidson College

C

Corey E. Tarwater

Department of Zoology and Physiology, University of Wyoming

P

Patrick A. Thorpe

Department of Biology, Grand Valley State University

M

Morgan W. Tingley

Department of Ecology and Evolutionary Biology, University of California

C

Christine L. Tischer

Sea and Sage Audubon

B

Benjamin A. Tonelli

Department of Biological Sciences, Clemson University

M

Melanie L. Truan

Museum of Wildlife and Fish Biology, University of California–Davis

C

Cornelia W. Twining

Department of Fish Ecology and Evolution, Swiss Federal Institute of Aquatic Sciences and Technology

J

Jennifer J. Uehling

Department of Ecology, Evolution and Organismal Biology, Iowa State University

C

Carol Vleck

Department of Biology, West Chester University

D

David Vleck

Department of Biology, West Chester University

M

Michael L. Watson

The Holden Arboretum

N

Nathaniel T. Wheelwright

Biology Department, Bowdoin College

L

Linda A. Whittingham

Department of Biological Sciences, University of Wisconsin–Milwaukee

D

David W. Winkler

SABER Consulting

C

Casey Youngflesh

Department of Biological Sciences, Clemson University

C

Cedric Zimmer

Laboratoire d’Ethologie Expérimentale et Comparée, Université Sorbonne Paris Nord

M

Maren N. Vitousek

Department of Ecology and Evolutionary Biology and Lab of Ornithology, Cornell University