Studies On Echolocation Calls During Postnatal Growth And Behaviors Of Mother-infant Communication Of 2 Species Of Bats

14 of the 19 chiropteran families lack data on postnatal growth, and <3% of known bat species have been investigated regarding their growth and development. Eighty percent of studies on postnatal growth are restricted to the family Vespertilionidae, particularly bats of the temperate zone. Studies on subsequent postnatal growth and on mother-infant communication of bats are important for understanding the aspects of their life history and for understanding a wide range of ecological, behavioral, and developmental patterns. Study of postnatal growth and Mother-infant communication of bats is one of the major fields in bats study.Changes in the echolocation calls of young Rhinolophus ferrumequinum and Myotis daubentoni at different growth stages were researched by marking and recapturing method in this paper. The equation for estimating age of young M. daubentoni was obtained by measuring length of forearm and length of the total gap of the fourth metacarpal-phalangeal joint. The behaviors of the mother-infant communication of R. ferrumequinum and M. daubentoni were observed in a laboratory (volume: 9m×4m×4m) and the Dalazi cave in the field. The results were as follows:1. The dominant frequency and pulse duration were increased when young greater horseshoe bats grew increasingly. However, only was the dominant frequency increased when young M. daubentoni grew increasingly, but the pulse duration and interpulse interval were decreased.2. Length of forearm of M. daubentoni followed a linear pattern of growth at early stage of postnatal growth, but the rate of increase decreased therafter. The length of the total gap of the fourth metacarpal-phalangeal joint showed a linear increase up to 13 days, followed by a linear decrease until it closed. Length of forearm was the best parameter for estimation of age of M. daubentoni before 13 days after birth, but afer 13 days of age, the total gap of the fourth metacarpal-phalangeal was the best one.3. The mothers and their infants of R. ferrumequinum and M. daubentoni were identified each other by the smell and calls emitted by them. Following the growth of young bats, the relationships of mother and infant were decreased. At the late of lactation, the young bats would close with their mothers, but the mothers became lack of interest with the young. Mother of two species of bats only nurtured the young bats which were produced by themselves, and the common nurturing young bats at intraspecies level was not observed.4. There were some significant differences of echolocation calls between the greater horseshoe bats closed with their young bats and they hung. At this first state, the dominantfrequency was higher than that at the later state (t=4.79, p<0.05), but pulse duration and interpulse interval were lower (t=-3.67, p<0.05;t=-17.88, p<0.05, respectively). There were also some significant differences of calls emitted by M. daubentoni between the bats approached their young bats and they hung. At the first state, the dominant frequency was lower than that at the later state (t=-2.46, p<0.05), but the pulse duration was higher (t=4.46, p<0.05). Furthermore, the interpulse interval was not significant difference at two states (t=-1.92, p>0.05).