科研之友
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摘要
Increased density, increased intraspecific aggression and reduced fear of humans have been pointed as the easily observable and frequently described characteristics of "urbanized" wildlife. The interaction among these variables and the relationship with urbanization condition are poorly understood. In this paper, we explore the reasons why the density, wariness and intraspecific aggression have an intense relationship in the urban populations of the red-bellied squirrel (Callosciurus erythraeus castaneoventris) in Longjiang riverside of Yizhou, Guangxi, China. The study was conducted in the fall of the years 2008-2011. Results indicated that the squirrel's density ranged from 0.961/ha (fall 2008) to 1.18/ha (fall 2011). The startle distance for the red-bellied squirrels varied at this location from 2.07 +/- 0.35 m (fall 2008) to 1.93+0.42 m (fall 2009), 1.87 +/- 0.06 m (fall 2010) and 1.92 +/- 0.14m (fall 2011) and there was no evidence of a relationship between the red-bellied squirrel density and wariness (R(2)adj = -0.67, p = 0.46). Observation for acts of intraspecific aggression among the squirrels was conducted for 108 hours. The mean values ranged from 7.12/h +/- 0.18 (fall 2009), to 10.24/h +/- 0.05 (fall 2011). There was a positive relationship between density and intraspecific aggression (R(2)adj = 0.92,p = 0.02). The Vanderloeg and Scavia selectivity index (Ei) indicated that red-bellied squirrels showed preference for habitat variability in water distance, slope, elevation, shrub distance, distance to human disturbance, shrub density, canopy density, shelter from wind direction, food abundance, distance to trees, slope position and tree density. Itt was found that hidden factors, geographical factors, interference factors, food factor and water factor features were the most important factors in determining the autumn habitat selection of the red-bellied squirrels. The present results support the idea that the habitat preferences of the red-bellied squirrels are a trade-off between suitable habitat features and avoidance of potential human interactions, and also transformed adaptation mechanisms in the urbanized fragmented habitats.
