Factors affecting the nesting success of Swainson's thrush (Catharus ustulatus) along an elevational gradient

Montane birds face several ecological challenges during the breeding season, including nest predators, competition for territory, and food availability. The continuing effects of climate change are causing shifts in these plant and animal communities, as well as changes in abiotic factors such as increased temperature and precipitation effects, adding additional stressors that could affect nest survival, putting their populations at risk. The Swainson’s thrush (Catharus ustulatus) is migratory songbird which is moderately common and breeds along a wide elevation gradient within this system (200-1,250m). Populations of Swainson’s thrush were once declining, though recent research shows their ranges to be shifting downwards, potentially as the result of increased precipitation and temperature at higher elevations. Although lower elevations might be more favorable in terms of climactic conditions, nest predation is higher at lower elevations in other systems. Thus, this species might be fa...