The Study Of The Echolocation Calls Of Myotis Macrodactylus In Different River Habitats

Myotis macrodactylus has been listed as a Lc species by Red List of Threatened of International Union for Conservation of Nature, which mainly distributes in Japan, Russia, Siberia and Korea. In 2008, M. macrodactylus has been found in Ji'an, Jilin Province, China. The bats forage over the water surface by'trawling'. We divided the water habitats in micro-scale, and examined the parameters of echolocation calls in 13 different river habitats and 1 land habitat. We analyzed the parameters of echolocation calls and discussed the adaptability between echolocation call and ecological characteristic. The results were as follows.1. Echolocation calls of Myotis macrodactylus were FM (Frequency modulation) with 1-2 harmonics in different habitats. In our study, M. macrodactylus showed a higher peak frequency(54.63±5.10), longer duration(4.65±1.09) and broader bandwidth (start frequency, 94.39±33.78; end frequency, 39.40±4.03) than that in Hokkaido. The difference might result from the variation of geography and habitats, or the annum.2. M. macrodactylus used different echolocation design between land and river habitats, with a significant variation for the echolocation parameters (p < 0.05), and a discrimination value in 66.1%. The result was confirmed from the compariation between the land and the three relative open or close river habitas, in which the water surface characteristic were different. Echolocation behavior was interferenced with the river, M. macrodactylus had an Jamming avoidance response to river by a higher peak frequency and broader bandwidth to acquire detailed information of the target, and by a shoter duration and longer interpulse interval to avoid overlap. While the amplitude didn't increase.3. Physical structure of the water surface influenced the design of echolocation potentially. Some echolocation parameters were different in significantly for the three habitats, which were smooth water surface habitat, clutter water surface habitat and rapid water surface habitat. It is in a large degree for the clutter water to increase the multiplicity of habitat and the difficulty of foraging. The lowest frequency, shortest duration, steepest pulse was shown in habitat CNO5-10, indicating a echolocation strategy to clutter habitats, which showed an adaption to the clutter habitat. M. macrodactylus used a lower frequency, narrower bandwidth, longer duration and shallower call in relative open river habitats, which shows the phenotypic flexibility and eco-adaptability for echolocation call of M. macrodactylus.4. There was a significant difference among the river habitats (p < 0.05). For the smooth habitats, the peak frequency and bandwidth gradually depress, but the pulse duration gradually increase, the pulse gradually shallow with the increasing of the open degree of habitats. It showed a similar regular alteration among rapid habitats, while not the same as clutter habitats. We suggested that riparian vegetation wasn't an uninfluenced factor to the echolocation when the smooth river habitat was open enough.The echolocation of M. macrodactylus was adjusted to the right habitat.In all, it is thus evident that echolocation calls were certainly diversity in different river habitats, and so do the land and river habitats. Physical structure and characteristic of river habitats affect echolocation design in part degree. The echolocation call of M. macrodactylus had phenotypic flexibility and eco-adaptability. Acoustic plasticity was essential for the bats foraging in complex habitats, and was an result of the interaction between echolocation and environmental, determining the utilization degree of habitat resources.