Behaviour and body weight fluctuations of the Eurasian Red Squirrel (Sciurus vulgaris) in the mating season

Abstract

One female squirrel was studied in Nopporo Forest Park (43°20′N, 141°30′E), in west Hokkaido, Japan. During the pregnancy, she moved from a main nest to the breeding nest and then built a few new nests (5 spherical dreys). In lactation stage, she departed from her den later in the morning than during the pregnancy period. When other male squirrels were in proximity, she attacked them. She carried her litters and moved to other dreys about 30-days after parturition. Her body weight was weighed ranged from 371 g to 397 g at the pregestation stage, increased steadily during the pregnancy period, and attained the maximum, 504 g, just before parturition. After parturition, her body weight decreased abruptly about 12% (from 504 g down to 443 g). Her daily change rate of body weight (DCBW) was 2.91% in the pregestation period, 3.03 % in the pregnancy period, and 6.93 % in the lactation period.