Roost switching and population changes in nursery colonies in the Japanese northern bat, Eptesicus japonensis, at Norikura Kogen, over 29 years

Abstract

An ecological survey of the Japanese northern bat, Eptesicus japonensis, roosting in artificial structures was conducted at Norikura Kogen, Nagano Prefecture, central Honshu, from May to October 1990 to 2018. The Japanese northern bat forms nursing colonies to give birth and nurse infants. Roost switching occurs due to predatory activities and the improvement or abandonment of roosts. The start date of the formation of nursing colonies, the stability of the number of colonies, the maximum number of colonies, and the dissolution date of the nursing colonies changed each year. Populations in nursery colonies fluctuated from 77 individuals to 347 individuals.