The Effects of Weather on Breeding Productivity in the Northern Goshawk

The Northern Goshawk is a secretive forest raptor that serves as an indicator species for most of the forests in North America. Fairhurst and Bechard (2005) predicted that low temperatures in February and March, combined with heavy precipitation in April, would result in less breeding success and territory occupancy in the Northern Goshawk in northern Nevada. After observing lower than average occupancy and productivity in Northern Goshawks in the Minidoka Ranger District of the Sawtooth National Forest in Idaho during the breeding season of 2019, we launched a study using concepts from Fairhurst’s paper to explain the impact of the year’s cold and wet springtime weather on the goshawks in our study area. We evaluated the effects of cumulative precipitation over three time periods (January through May), mean monthly temperature, mean daily low temperature and minimum temperature during the incubation period (the month of May), and Average Snowpack Depth in the second and third week of April (April 8 - April 22), a time corresponding to the expected egg-laying period within the area. To minimize the effect of psuedo-replication, we included Year and Territory as random effects. We used linear mixed models with a binomial distribution for occupancy, and Poisson distribution for productivity