Biology
Polygyny Threshold Model and Territory Quality in Red-Winged Blackbirds
Quick fact
The polygyny threshold model predicts that a female will accept polygyny when the quality of a male's territory is so high that the benefits of nesting there outweigh the costs of sharing his help and resources, and this has been supported by experimental manipulations of territory quality in red-winged blackbirds.
Why this is interesting
Imagine a female red-winged blackbird searching for a nest site. She could choose a single male on a low-quality territory, or she could join an already-mated male on a prime marsh. Why would she ever 'settle' for second best?