Study On Food Stealing And Their Effect Factors In Short-nosed Fruit Bat, Cynopterus Sphinx

There are several examples about sharing food in animalia among relatives, mates, dominant individuals and subordinate individual, include the passive sharing and proactive sharing, in which food stealing belongs to the passive sharing. We found food stealing between individuals in the process of behavioral observation in short-nosed fruit bat, Cynopterus sphinx, that is the stealer snatches food from the holder who is fed, in most cases the holder defent their food,however a part of holders choose to tolerate. Cynopterus sphinx is one kind of fruit bats, usually be polygynous or more male live in a tent. We observed and researched food stealing behavior under the condition of laboratory incubation in a group. The results showed:(1) from the skills,stealer can improve the grabing efficiency by changing direction and distance and so on. Among which occurrence frequency that a stealer fly and clasp the holder suddenly is the least, however the hit rate of robbing is the highest by this way.(2) compared to male,not only the number of food stealing(t=-2.477, P=0.023) but also the number of successful food stealing(t=-2.511, P=0.022)for female are more significantly. We believe that what happens in food stealing of gender differences, mainly on reproduction investment of the male is far lower than the female,then the female is in a chooser position, the male in a selected position, therefore, the male may acquire mating opportunities through this kind of share resources in an attempt to get the favour of female.(3) With the volume and weight of food increase, times of food stealing and successful food stealing rate rise under the condition of adquent food. In other word,bigger food means more food stealing occured and successful rate increased. The results suggested that large food that contained a lot of energy were more attractive to another individuals and rob predator would put into greater willingness to grab. Meanwhile this also implies that the action of dog bats grabing is more than energy. In addition, under the condition of the food is defecient,the frequence of dog bat grabing is increasing comparing to food sufficient. The result indicated that bats dog stealing behavior is still has a certain relationship with energy demand.(4) Grooming is found between the individuals that polyculture in a group, and the most is among females that lives in a tent. The length of grooming is in correlated with food stealing times(r=0.559, P=0.038) and the same as successful food stealing times(r=0.659, P=0.010). So we speculate that the individuals groom for others were in exchange for food.(5) We hypothesized that there may be weaker level relations between individuals based on the phenomena that the grab action under conditions of sufficient food, be toleranced of stealing in the process of sharing food and the unjust relationship in sharing food.