Fission-fusion dynamics over large distances in raven non-breeders.
The influence of fission-fusion dynamics, i.e., temporal variation in group size and composition, on social complexity has been studied in large-brained mammals that rely on social bonds. Little is known about birds, even though some species like ravens have recently received attention for their socio-cognitive skills and use of social bonds. While raven breeders defend territories year-round, non-breeders roam through large areas and form groups at food sources or night roosts. We here examined the fission-fusion patterns of non-breeding ravens over years, investigating whether birds meet repeatedly either at the same or at different locations. We combined four large datasets: presence-absence observations from two study sites (Austria, Italy) and GPS-tracking of ravens across two study areas (Austria, France). As expected, we found a highly dynamic system in which individuals with long phases of temporary settlement had a high probability of meeting others. Although GPS-tagged ravens spread out over thousands of square kilometres, we found repeated associations between almost half of the possible combinations at different locations. Such a system makes repeated interactions between individuals at different sites possible and likely. High fission-fusion dynamics may thus not hinder but shape the social complexity of ravens and, possibly, other long-term bonded birds.
Department of Cognitive Biology, University of Vienna, Althanstrasse 14, A-1090, Vienna, Austria. mail@m-loretto.com.|Konrad Lorenz Forschungsstelle, Core Facility for Behaviour and Cognition, University of Vienna, Fischerau 11, A-4645, Grünau im Almtal, Austria. mail@m-loretto.com.
Matthias-Claudio
0000-0002-1940-3470
MC
Loretto
Department of Forest and Conservation Sciences, University of British Columbia, 3041 - 2424 Main Mall, Vancouver, B.C., V6T 1Z4, Canada.|Department of Biology, 1125 Colonel By Drive, Carleton University, Ottawa, K1S 5B6, Canada.
Richard
0000-0003-3191-7869
R
Schuster
Office National de la Chasse et de Faune sauvage, Délégation Régionale Occitanie, Actisud Bâtiment 12, 18 rue Jean Perrin, F-31100, Toulouse, France.
Christian
C
Itty
Office National de la Chasse et de Faune sauvage, Délégation Régionale Occitanie, Actisud Bâtiment 12, 18 rue Jean Perrin, F-31100, Toulouse, France.
Pascal
P
Marchand
Riserva naturale regionale del Lago di Cornino, I-33030 Forgaria nel Friuli, Udine, Italy.
Fulvio
F
Genero
Department of Cognitive Biology, University of Vienna, Althanstrasse 14, A-1090, Vienna, Austria.|Konrad Lorenz Forschungsstelle, Core Facility for Behaviour and Cognition, University of Vienna, Fischerau 11, A-4645, Grünau im Almtal, Austria.
Thomas
T
Bugnyar
D000818:Animals; D001522:Behavior, Animal; D046368:Crows; D005060:Europe; D005247:Feeding Behavior; D005260:Female; D008297:Male; D012919:Social Behavior