Directed seed dispersal by scatter-hoarding rodents into areas with a low density of conspecific seeds in the absence of pilferage

Abstract

Some species of scatter-hoarding rodents direct seed dispersal by dispersing seeds into areas where the densities of conspecific trees are low. This behavior seems to be an immediate response to cache pilferage and is accomplished by multiple movements. We evaluated whether this directed dispersal also occurs when the scatter-hoarding rodents Maxomys surifer disperse seeds away from parent trees when no pilferage has occurred. We simulated parent trees by releasing seeds at different sites in semi-natural enclosures, which prevent pilferage, in Xishuangbanna region, Southwest China. We found that M. surifer preferred to disperse seeds into areas with fewer conspecific seeds and that seeds cached in areas of low seed density were more likely to survive than those in areas of high density. Our results indicate that M. surifer could provide directed dispersal when they initially disperse seeds away from parent trees, without pilferage. This finding suggests that directed seed dispersal is not an immediate response after pilferage, but an instinctive behavior to reduce the potential for density-dependent cache pilferage. Further, our study indicates that directed seed dispersal is important to mast-seeding plants or species whose seeds are unlikely to be dispersed several times by scatter-hoarding animals.