Ecological correlates of alternative reproductive tactics: conspecific brood parasitism rates vary with nest predation and seasonal effects influenced by climate change

Ecological and social factors shape individual reproductive strategies. Climate change has wide-ranging effects on the timing of reproduction and availability of nesting sites for many birds. Ecological factors such as season length or predation rate could in turn affect the relative success rates of alternative reproductive tactics (ARTs). A new article by Pöysä (2024) featuring a long-term study of common goldeneyes Bucephala clangula highlights the role of climate change in altering rates of conspecific brood parasitism (CBP) by affecting nest initiation dates and season length. While some authors have emphasized the effects of spatial and temporal aggregation of nests in promoting tactics of reproductive interference, few studies have addressed the effects of environmental variables on rates of CBP and other ARTs. I review some of the evidence for a relationship between population-level nest predation rate and rates of CBP, principally in ducks and rails, and suggest a role for high rates of nest loss from all sources in the evolution of CBP and host responses. There is a need for further studies that examine environmental correlates of ARTs. Long-term studies have the highest potential to reveal how shifts in phenology and life history variables may respond to environmental perturbations. Comparative studies of similar species in remote geographic locations can add perspective of how different ecological variables affect the prevalence of ARTs.