Early successional habitats created through plantation harvesting benefit the Gray Nightjar (Caprimulgus jotaka): An 8-year survey in central Hokkaido, northern Japan

Abstract

ABSTRACT Early successional habitats and their associated species have been decreasing globally. In contrast, plantations have been expanding and their young stages (stand age ≤ 10 years) can serve as early successional habitats. The Gray Nightjar (Caprimulgus jotaka), a nocturnal bird species, breeds and forages in early successional habitats surrounded by forests; its populations have declined since the 1970s in Japan. Because nightjars are more abundant in warmer areas across Hokkaido, northern Japan, habitat creation through plantation harvesting was expected to promote nightjar abundance or occupancy in this region. To explore the effects of plantation harvesting on nightjar occupancy, we conducted an 8-year playback survey in a plantation landscape in central Hokkaido. We considered the effects of elevation as a surrogate for temperature. The results indicated that increasing young forest cover within 500 m of the centroid of each site enhanced nightjar occupancy, whereas elevation negatively affected occupancy. Therefore, at lower elevations, we predict a larger increase in occupancy probability with increasing young forest cover following plantation harvesting. Our results suggest that young forest creation in landscapes can contribute to Gray Nightjar conservation. To effectively create early successional species habitats through plantation harvesting, it is important to consider climate and elevation in the target area.