The capture of the Himalayan water shrew (Chimarrogale himalayica) in Vietnam

Water shrews of the genus Chimarrogale (Insectivora: Soricidae) represent an important but often unobserved component of the Vietnam mammal fauna. Usually associated with clear, swift-flowing forest streams in mountainous regions (Arai et al. 1985), Chimarrogale are reported to swim well underwater and have been observed "running over stones in the bed of a stream and plunging freely into the water" (Anderson 1879 p.139). Having restricted habitat and food requirements, they are only infrequently reported in surveys of small mammal diversity; however, with some knowledge of their natural history, specimens can be obtained using customized trapping methods. Here we comment on the capture of the Himalayan water shrew (Chimarrogale himalayica) using a combination of specialized stream traplines and pitfalls. Our purpose is to provide both practical information on capture methods, as well as natural history data gleaned in the process. Materials and methods Small mammal surveys were conducted at Huong Son Forest, Ha Tinh Province, Vietnam (18°22'N, 105°13'E) between 13 April-21 May 1998, and 18-25 April 1999. Habitats sampled include lowland (220-250 m) and premontane (250-1000 m) broad-leaved evergreen forest; and premontane conifer/broad-leaved evergreen forest with a dense understory of dwarf bamboo (1150-1270 m). A variety of conventional small mammal traps were employed including Victor snap-traps, Museum Special snap-traps and Sherman live traps. In addition to these we also used three specialized methods as part of an effort to capture water shrews: 1) pitfall traplines; 2) a stream jetty to direct amphibious mammals to one pitfall trapline; and 3) Victor traps set in the stream (Fig. 1).