The Study On The Self-grooming Behaviour And The Effect Of Odor On The Individual Identification In Tylonycteris Pachypus

The study of chemical communication in animal is always one of the hot spot in the research of animal behavior, mammals use scents for different purposes, such as marking territories, individual identification and kin recognition. Many research of chemical communication have been done with rodent and other mammals, but few have done with chiropteran. Study of chemical communication in flat-headed bats, Tylonycteris pachypus has been done in Longzhou County, Guangxi Zhuang Autonomous Region from May to October2011, which includes the roles of olfactory factors in mother-pup recognition, roostmate recognition and sex discrimination, and the effect of odor from different levels on self-grooming behaviour. The results are as following:1. The female of T. pachypus gives birth to twins at the end of May, and the offsprings fly in the last ten days of June. The offsprings live with their mother until they can fly, so there are many offsprings and female bats live together in the same colony during the breeding season. Evolutionary theory predicts that in gregariously breeding species, it is very important for parents to discriminate between their own and alien offspring to direct parental care to their own descendants. Self-made maze was used to test the partiality for female bats choosing the odor from their own and alien offsprings,303individuals had been tested and the result showed that female spent significantly more time on their own offsprings’ side of the arena in the maze (the positive selection is60.88±1.15%(n=303), the negative selection is39.12±1.15%(n=303)). There was significant differences in female bats choose their own and alien offsprings’ odor (P<0.001), and it shows that the female bats can recognize their own offspring by odor. All the samples had been divided into five groups based on their offspings’ forearms and weight, and different groups related to different ages of offsprings. Through the contrast experiment of5groups, the results indicated that the capacity of discernment grown with age, but close to time when offsprings could flew the capacity of discernment have decreased.2. Olfactory recognition is very important for mammals, the colonial animal will usually exclude the strange individual. The roosting groups of T. pachypus, which formed after foraging, were not limited in size by the dimensions of the roost site. Though the individual often exchange colony, the member of roosting groups are relatively stable. Self-made maze was used to test the partiality for bats choosing the odor from their own and alien roosting groups, and all the samples had been divided into4groups based on their sex (♀-♀♀、♀-♂♂、♂-♀♀、♂-♂♂).243samples had been tested and the result showed that the female bats can distinguish roostmates from strangers by odor in both sex, and male bats can distinguish roostmates from strangers only in male, it had not show difference in scent-choice when male bats meet odor from the roostmates and strangers female individual.Many mammals studied show the ability in use scents for sex recognition, and olfaction is an important cue for mate-choice. The ability of T. pachypus to distinguish between males and females in scent-choice experiments was tested, the results showed that both sex of bats did not show any preference in either trials. We propose that the period when we made the test was not oestrum for the bats, so it did not show any difference when the bats met the odor from opposite-sex conspecific.3. Grooming is an innate stereotyped behavior that exists in most animal species. Generally, self-grooming of animals can remove ectoparasites and clean the pelage, and lower their body temperature, etc. Self-grooming in mammals following the odor of a conspecific encounter is considered to be a form of olfactory communication. We use the odor from the male, include the conspecific bats from different colony and forest, and from different species, include T. robustula and human, to activate the T. pachypus. The self-grooming behavior of T. pachypus which has been activated by the odor showed significant differences when compared with the control group. The self-grooming behavior had not show difference when T. pachypus activated by the odor from conspecific individual, but showed significant differences by the odor from different species. It was also found that self-grooming of T. pachypus showed difference between sexes when activated by male odor, it might be relative to sex pheromone in olfactory communication.