Persnickety Parents: How Parental Care Behavior affects Songbird Nest Success

Kenney, Macy
Incubation attentiveness and rhythms can have important fitness consequences for songbirds through influencing their number and quality of successful young. Songbirds are highly susceptible to nest failure due to predation given their use of sessile reproductive sites, and have been shown to alter their nesting behavior in response to perceived predation risk. One sagebrush-obligate songbird, the Brewer's sparrow (Spizella breweri), has been shown to adjust their parental care behavior following failed nesting attempts. We therefore expected that sage thrasher (Oreoscoptes montanus) nest survival also may be affected by parental care behaviors. Specifically, we predicted that birds with successful broods would take fewer trips to the nest and have longer bout lengths, reducing the likelihood that their nest would be discovered by predators. We analyzed parental care videos from sage thrasher nests during incubation to assess differences in parental behaviors between successful and unsuccessful nesting attempts. We assessed average on- and off-bout lengths, total nest attentiveness, and average number of trips taken to the nest per hour. Videos were recorded from May-August 2015 and 2016 at sites in the Upper Green River Basin, WY as part of a larger study of sagebrush-obligate songbird nest success. Preliminary results suggest that sage thrashers that successfully fledge young tend to have longer on-bout and shorter off-bout length, higher total nest attentiveness, and have fewer visits per hour to the nest. Identifying whether and how sagebrush-obligate songbirds mitigate predation risk via behavioral plasticity will facilitate better understanding of how birds respond to ongoing human disturbance, such as energy development, which alters habitat and predator communities.
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