Seasonal patterns in the distribution of Northern Pygmy-Owls (Glaucidium gnoma) across an elevational gradient

Abstract

Northern Pygmy-Owls (Glaucidium gnoma) occur in mountainous regions of western North America, but their movements and seasonal patterns of distribution are poorly understood. Assumed to be altitudinal migrants, data evaluating their seasonal distributions are scarce. We quantified the seasonal distributions of Northern Pygmy-Owls across elevations in the Oregon Coast Range, USA, by using call playbacks to elicit responses. We hypothesized that pygmy-owls would be more widely distributed at higher elevations during the summer, and during the cooler winter months their distributions would shift downslope to more moderate climates. Northern Pygmy-Owls responded at all elevations and in all seasons but responded most frequently at middle elevations. The pattern of responses with respect to season and elevation was consistent in the 2 years of our study (2020–2021), suggesting that they were not altitudinal migrants in our study area during those years. However, characterizing altitudinal migration from distributions alone requires careful interpretation so we encourage further studies using tagged and tracked individuals.