TY - JOUR
T1 - Home field advantage, not group size, predicts outcomes of intergroup conflicts in a social bird
AU - Strong, Meghan J.
AU - Sherman, Benjamin L.
AU - Riehl, Christina Pauline
N1 - Funding Information:
Funding for this research was provided by the Princeton Environmental Institute at Princeton University . We thank the Smithsonian Tropical Research Institute for continued support of this long-term study, especially Owen McMillan, Egbert G. Leigh, Jr, and John Christy. Field assistants Chiti Arvind, Luke Carabbia, Laura Jara Reyes, Amanda Savagian, Zachariah Smart and Wendy Webber helped to collect field data. For assistance in ArcMap, we thank Tsering Wangyal Shawa of the Map and Geospatial Information Center of the Princeton University Library, and William Guthe of the Office of Information Technology at Princeton University.
Funding Information:
Funding for this research was provided by the Princeton Environmental Institute at Princeton University. We thank the Smithsonian Tropical Research Institute for continued support of this long-term study, especially Owen McMillan, Egbert G. Leigh, Jr, and John Christy. Field assistants Chiti Arvind, Luke Carabbia, Laura Jara Reyes, Amanda Savagian, Zachariah Smart and Wendy Webber helped to collect field data. For assistance in ArcMap, we thank Tsering Wangyal Shawa of the Map and Geospatial Information Center of the Princeton University Library, and William Guthe of the Office of Information Technology at Princeton University.
Publisher Copyright:
© 2017 The Association for the Study of Animal Behaviour
PY - 2018/9
Y1 - 2018/9
N2 - Research on cooperatively breeding birds usually focuses on social dynamics within the breeding group, but conflict between groups can also affect individual fitness and the evolution of sociality. Here we investigate the causes and consequences of competition between groups of communally breeding greater anis, Crotophaga major, over a 10-year field study. Social groups were spatially clustered into loose aggregations that showed a moderate degree of reproductive synchrony. However, competition between neighbouring groups for nesting sites was intense, occasionally leading to wholesale destruction of a group's nesting attempt and abandonment of the site. We documented 18 cases in which a group's entire clutch of eggs was ejected from the nest during the laying or incubation period, often accompanied by behavioural observations of conflict with a neighbouring group. Clutch destruction typically occurred when two groups attempted to nest in close proximity on high-quality sites: nearest-neighbour distance and nest site type were the strongest predictors of clutch destruction. Surprisingly, group size did not predict whether or not a group's clutch would be destroyed, and small groups sometimes ousted larger groups. By contrast, ‘home field advantage’ did have a significant effect: groups that had previously nested on the site were more likely to destroy the clutches of newly established groups, and this effect increased with the number of years that the group had nested there. Together, these results support previous evidence that competition between groups for high-quality nesting sites is an important driver of communal breeding, and they highlight the importance of location and past history in determining the outcome of intergroup contests in social species.
AB - Research on cooperatively breeding birds usually focuses on social dynamics within the breeding group, but conflict between groups can also affect individual fitness and the evolution of sociality. Here we investigate the causes and consequences of competition between groups of communally breeding greater anis, Crotophaga major, over a 10-year field study. Social groups were spatially clustered into loose aggregations that showed a moderate degree of reproductive synchrony. However, competition between neighbouring groups for nesting sites was intense, occasionally leading to wholesale destruction of a group's nesting attempt and abandonment of the site. We documented 18 cases in which a group's entire clutch of eggs was ejected from the nest during the laying or incubation period, often accompanied by behavioural observations of conflict with a neighbouring group. Clutch destruction typically occurred when two groups attempted to nest in close proximity on high-quality sites: nearest-neighbour distance and nest site type were the strongest predictors of clutch destruction. Surprisingly, group size did not predict whether or not a group's clutch would be destroyed, and small groups sometimes ousted larger groups. By contrast, ‘home field advantage’ did have a significant effect: groups that had previously nested on the site were more likely to destroy the clutches of newly established groups, and this effect increased with the number of years that the group had nested there. Together, these results support previous evidence that competition between groups for high-quality nesting sites is an important driver of communal breeding, and they highlight the importance of location and past history in determining the outcome of intergroup contests in social species.
KW - Crotophaga major
KW - cooperative breeding
KW - greater ani
KW - group stability
KW - intergroup competition
KW - social behaviour
KW - territoriality
UR - http://www.scopus.com/inward/record.url?scp=85028654285&partnerID=8YFLogxK
UR - http://www.scopus.com/inward/citedby.url?scp=85028654285&partnerID=8YFLogxK
U2 - 10.1016/j.anbehav.2017.07.006
DO - 10.1016/j.anbehav.2017.07.006
M3 - Article
AN - SCOPUS:85028654285
SN - 0003-3472
VL - 143
SP - 205
EP - 213
JO - Animal Behaviour
JF - Animal Behaviour
ER -