The effect of climate change on avian offspring production: A global meta-analysis
Authors: Halupka Lucyna , Arlt Debora , Tolvanen Jere , Millon Alexandre , Bize Pierre , Adamík Peter , Albert Pascal , Arendt Wayne J. , Artemyev Alexander V. , Baglione Vittorio , Bańbura Jerzy , Bańbura Mirosława , Barba Emilio , Barrett Robert T. , Becker Peter H. , Belskii Eugen , Bolton Mark , Bowers E. Keith , Bried Joël , Brouwer Lyanne , Bukacińska Monika , Bukaciński Dariusz , Bulluck Lesley , Carstens Kate F. , Catry Inês , Charter Motti , Chernomorets Anna , Covas Rita , Czuchra Monika , Dearborn Donald C. , de Lope Florentino , Di Giacomo Adrián S. , Dombrovski Valery C. , Drummond Hugh , Dunn Michael J. , Eeva Tapio , Emmerson Louise M. , Espmark Yngve , Fargallo Juan A. , Gashkov Sergey I. , Golubova Elena Yu. , Griesser Michael , Harris Michael P. , Hoover Jeffrey P. , Jagiełło Zuzanna , Karell Patrik , Kloskowski Janusz , Koenig Walter D. , Kolunen Heikki , Korczak-Abshire Małgorzata , Korpimäki Erkki , Krams Indrikis , Krist Miloš , Krüger Sonja C. , Kuranov Boris D. , Lambin Xavier , Lombardo Michael P. , Lyakhov Andrey , Marzal Alfonso , Møller Anders P. , Neves Verónica C. , Nielsen Jan Tøttrup , Numerov Alexander , Orłowska Beata , Oro Daniel , Öst Markus , Phillips Richard A. , Pietiäinen Hannu , Polo Vicente , Porkert Jiří , Potti Jaime , Pöysä Hannu , Printemps Thierry , Prop Jouke , Quillfeldt Petra , Ramos Jaime A. , Ravussin Pierre-Alain , Rosenfield Robert N. , Roulin Alexandre , Rubenstein Dustin R. , Samusenko Irina E. , Saunders Denis A. , Schaub Michael , Senar Juan C. , Sergio Fabrizio , Solonen Tapio , Solovyeva Diana V. , Stępniewski Janusz , Thompson Paul M. , Tobolka Marcin , Török János , van de Pol Martijn , Vernooij Louis , Visser Marcel E. , Westneat David F. , Wheelwright Nathaniel T. , Wiącek Jarosław , Wiebe Karen L. , Wood Andrew G. , Wuczyński Andrzej , Wysocki Dariusz , Zárybnická Markéta , Margalida Antoni , Halupka Konrad 
Published: May 2023

Climate change affects timing of reproduction in many bird species, but few studies have investigated its influence on annual reproductive output. Here, we assess changes in the annual production of young by female breeders in 201 populations of 104 bird species (N = 745,962 clutches) covering all continents between 1970 and 2019. Overall, average offspring production has declined in recent decades, but considerable differences were found among species and populations. A total of 56.7% of populations showed a declining trend in offspring production (significant in 17.4%), whereas 43.3% exhibited an increase (significant in 10.4%). The results show that climatic changes affect offspring production through compounded effects on ecological and life history traits of species. Migratory and larger-bodied species experienced reduced offspring production with increasing temperatures during the chick-rearing period, whereas smaller-bodied, sedentary species tended to produce more offspring. Likewise, multi-brooded species showed increased breeding success with increasing temperatures, whereas rising temperatures were unrelated to reproductive success in single-brooded species. Our study suggests that rapid declines in size of bird populations reported by many studies from different parts of the world are driven only to a small degree by changes in the production of young.