Is Mate Switching an Adaptive Behavior in House Wrens?

Student: Abbi Turner ’20
Research Mentors: Dustin Reichard (OWU Department of Zoology) and Elizabeth Schultz (OWU Department of Zoology)

The quality of an individual’s mate directly affects their fitness. When mate quality is poor, e.g., low parental effort, poor body condition, reproductive success can be low. Mate switching is a behavior that occurs in many avian species that could potentially increase reproductive success in individuals that are initially paired with low-quality mates. This behavior occurs when a pair bond is severed, a new mate is found, and a new pair bond is formed. Mate switching is most commonly observed between breeding seasons, but multi-brooded house wrens (Troglodytes aedon) will frequently switch mates within a single breeding season between nesting attempts. We studied mate switching behavior in house wrens to examine its potential adaptive value. We caught male and female house wrens using mist nets, and blood samples were collected to measure circulating glucocorticoid hormones associated with stress and collect DNA for paternity testing. We banded each individual with a unique color combination to identify them while observing pairing and parental care behavior. We hypothesized that individuals who switched mates would not have higher fitness than the individuals who did not switch mates with fitness being measured as the number of offspring that fledge. Data analysis for this study is ongoing, but preliminary results suggest that mate switching is common in our population regardless of whether or not the first breeding attempt is successful.

Our study focused on mate switching behavior in a common, backyard songbird, the House Wren (Troglodytes aedon). Mate switching is essentially a divorce where at least one member of the pair leaves to find a new mate. We were interested in determining if mate switching is beneficial by studying whether the adults who switched mates had more offspring than the adults who did not switch mates. To measure switching behavior and offspring production, we attached unique combinations of colored bands to the legs of adult wrens and observed which wrens paired together and also collected blood samples from both adults and nestlings for paternity testing.