Spacing and kinship in the Formosan squirrel living in different habitats

Abstract

Spacing and kinship of the Formosan squirrel, Callosciurus erythraeus thaiwanensis, were studied in two different habitats. One, native habitat in the woods of Kenting, southern Formosa, was rich in available food throughout the year and had several species of predators. The other, a site in Kamakura, central Japan where squirrels had been introduced, had relatively scanty food and few potential predators. 1. Home ranges among males and between sexes overlapped extensively in both habitats. 2. Females occupied exclusive home ranges in Kamakura but had small overlapping home ranges in Ken-ting. 3. Most males disappeared from their natal areas at 1 year old in both habitats (86% in Kamakura and 93% in Ken-ting), but less females disappeared (36% in Kamakura and 35% in Ken-ting). 4. In Kamakura, daughters settled adjacent to the mother or inherited the home range of the mother, but never shared the mother's home range. In Ken-ting, 35% of daughters shared the home range with their mothers. 5. Tolerance among female kin in Ken-ting was probably facilitated by the richness of available food throughout the year, and functioned to reduce predation risk via alarm calling and mobbing.

Invasion dynamics of an introduced squirrel in Argentina

“…Published data on density and home range area were used to estimate habitat suitability for the different habitat types. The lowest density of red‐bellied squirrels, 2–3 individuals ha −1 , was reported in a Taiwanese plantation of Japanese fir ( Cryptomeria japonica ) (Lin and Yo 1981), whilst 5–7 adults ha −1 were found in temperate mixed forest in Japan and in native habitat (Tamura et al 1989). Home range size and overlap was always larger in males than females (Tamura et al 1989, Yo et al 1992b).…”

“…The lowest density of red‐bellied squirrels, 2–3 individuals ha −1 , was reported in a Taiwanese plantation of Japanese fir ( Cryptomeria japonica ) (Lin and Yo 1981), whilst 5–7 adults ha −1 were found in temperate mixed forest in Japan and in native habitat (Tamura et al 1989). Home range size and overlap was always larger in males than females (Tamura et al 1989, Yo et al 1992b). Tamura et al (1987, 1989) reported mean home range sizes of females of 0.5–0.7 ha, which greatly overlapped with male home ranges but not with those of other females, and mean home range sizes for males of 2.2–3.8 ha, which greatly overlapped with both male and female home ranges.…”

“…Observations of predation on the nests of native birds have been reported in the Pampas (Pereira et al 2003). Studies conducted in Japan, where it was first introduced in 1935, have reported high population growth and adaptability to new environments, damage to plantations, garden trees, and cables, and predation of native birds (Tamura et al 1988, 1989, Azuma 1998, Miyamoto et al 2004). The species was also introduced into France in the 1970s, where it now causes damage to trees and crops (Jouanin 1992).…”

Chemical components of hardwood barks stripped by the alien squirrel Callosciurus erythraeus in Japan

“…The squirrels also damaged conifer plantations in Taiwan, their original habitat (Hwang et al 1979;Wang and Kuo 1980). We have frequently observed from winter to early spring that Formosan squirrels debark and lick tree saps in Kanagawa Prefecture, Japan (Tamura et al 1989). Chang (1976) reported that the Formosan squirrels in Taiwan stripped barks and fed on sap from March to May.…”

Postcopulatory mate guarding by vocalization in the Formosan squirrel

“…Body weight, sex, and maturity were recorded each time that squirrels were captured. Further information on the study site and trapping methods is available in Tamura et al (1988Tamura et al ( , 1989, When I encountered a squirrel along the census routes, individual identification, location, time, and behaviour were recorded. When vocalizations were detected, I recorded the location and behaviour of the caller, the target of calling, the total duration of calling, and the reactions of neighbouring squirrels.…”