Cooperation, conflict, and crèching behavior in goldeneye ducks

Area of Science:

• Behavioral Ecology
• Evolutionary Biology
• Ornithology

Background:

• Crèching behavior, or brood amalgamation, involves offspring being raised by non-genetic parents.
• Existing hypotheses often assume crèching is accidental or provides social benefits.

Purpose of the Study:

• To propose and test a new framework for understanding crèching behavior.
• To investigate the roles of brood desertion and brood adoption in crèching.
• To examine the selective pressures on parents and offspring in this context.

Main Methods:

• Developed a graphic model to predict parental brood desertion.
• Experimentally manipulated brood size in Barrow's goldeneyes (Bucephala islandica).
• Observed duckling acceptance and rejection by host broods of varying ages.

Main Results:

• Parental desertion occurred when brood size was experimentally reduced.
• Duckling adoption success depended on host brood availability and age; young broods (<10 days) accepted foreign ducklings, while older broods rejected them.
• No discernible benefits or costs of adoption were found for host females.

Conclusions:

• Crèching behavior results from selection on adults to desert broods when continued investment is costly.
• Selection favors deserted ducklings joining other broods for parental care.
• Crèching in goldeneyes represents reproductive parasitism, involving parent-offspring and intergenerational conflict.