How Large Cooperative Bird Groups Avoid Local Competition

Large cooperative groups are a common sight in nature. Their existence is puzzling, however, because local competition should keep groups relatively small. A simple but untested way large groups can avoid the problem of local competition is by increasing their resource base. We will conduct a systematic review and phylogenetic meta-analysis to look for evidence of this effect in wild populations of cooperatively breeding birds. Our effect size will be the strength of the correlation (Zr) between group size and territory area. We will additionally look for evidence of how territory size changes when a specific group changes in size.