]pn. ]pn. ]. Environ. Entomo 1. Zoo 1. 21 (3) : 155 -164 (2010) 環動昆第21 巻第3号: 155 -164 (2010) Original Original article Subterranean Subterranean spatial utilization of the lesser ]apanese mole ， Mogerl α imaizumii (Kuroda ， 1957) Atsushi KASHIMUR A， J) ，2) Kunihito MOTEKI ，l) ，3) Yosuke KIT AMUR A， 1) Daiju HA Y ASHI ，1) Yuu Shimoyokkaichi ，l) Akio SHINOHAR A，4) Tetsuo MORIT A， 2) ，3) and Kimiyuki TSUCHIYA J) ，5) 1) 1) Laboratory of Wild Animals ，Tokyo University of Agriculture ，Atsugi ，Kanagawa 243 - 0034 ，J apan 2) Department of Environment and Resource Sciences ，Interdisciplinary Graduate School of Agriculture and Engineering ，University of Miyazaki ， Miyazaki 889-2192 ， Japan 3) 3) Department of Plant and Animal Sciences ， Graduate School of Agriculture ， University of Miyazaki ， Miyazaki Miyazaki 889-2192 ， Japan 4) 4) Division of Bio-Resources ， Frontier Science Research Center ，University of Miyazaki ，Kiyotake ， Miyazaki 889-1692 ， Japan 5) 5) Applied Biology Co. ，Lt d. ，Minato-ku ，Tokyo 107 】 0062 ， Japan (Received (Received : June 15 ， 2009 ; Accepted : Janu ぽ y 12 ， 2010) Abstract We investigated the subterranean spatial utilization of the lesser Japanese mole ，Mogera imaizumii. We attached a radio radio transmitter to 8 individuals and conducted 9 sessions of continuous radio 田 tracking for up to 48 h. The depth of the the moles was estimated based on the strength of the radio signa l. In addition ，we measured soil temperature and the abundance of so 江 animals as potential prey items at several depths to determine their effect on the vertical distribution distribution of the moles. The home range size was negatively correlated with the total biomass of soil animals and the the home range was expanded during the breeding season. The vertical distribution of the moles changed seasonally A soil temperature of 23.0'C appeared to be the threshold above which the moles chosεto use the shallow soil layers. The utilization of this zone during the winter was likely due to the overlap with the breeding season. this period ，male moles actively search for receptive females. In summary ， our data suggest that the seasonal 記s the the vertical distribution of moles may be explained ， in par t， by changes in soil tεmperature. Furthermore ， reproductive reproductive state may also play a role in determining the vertical distribution of individual moles. Key words : Lesser J apanese mole ，Mogera imaizumii ， depth utilization ，home range ，radio telemetry. Introduction refuge from predators and a more favorable microclimate (Nevo ，1999 ; Burda et al. ，2007) A number of subterranean mammal species However ，little is known about the use of these tunnel construct construct tunnel systems in which they spend the systems because of the difficulties observing the majority majority of their life. These tunnels provide a stable behavior of subterr 註nean mammals. microclimate microclimate and shelter from terrestr 匂 1 predators Moles are known to construct elaborate ， three (Nevo ， 1999 ; Buffenstein ， 2000 ; Busch et al. ， 2000 ; dimensional tunnel systems (Godfrey and Crowcrof t， Burda et al. ， 2007). The tunnel systems typically 1960 ; Mellanby ， 1971 ; Hartman ， 1983 ; Gorman and consist consist of shallow and deep tunnels that extend both Stone ， 1990 ; Yokohata ， 1998 ;Y oshiyuki ，2002). These horizontally horizontally and vertically underground. It is generally animals spend their entire life in these tunnels where thought thought that the shallow tunnels are used for foraging they forage ，breed ，and rear their young. During the whereas the deeper tunnels are thought to provide summer the moles create shallow tunnels that are Corresponding Corresponding author : [email protected] 155 一一 KAS Hl MUI~A elαl visible visible from the surface. Conversely. in the wintεr ， the presence of mole-hills signifies that the moles are 醐ethods removing soil from deeper tunnels. Based on these observations ，it is thought that the vertical distribution Studyarea of of moles varies seasonally (Godfrey and Crowcrof t， The study was conducted in the gardens of the 1960 1960 ; Mellanby ， 1971 ; Gorman and Stone. 1990). It is Atsugi Campus. Tokyo University of Agriculture. hypothesized hypothesized that the seasonal changes in vertical Kanagawa Prefecture between May 2004 and distribution distribution is a response to changes in soil February 2006. The garden had a number of trees. temperature and/or distribution of their prey including Japanese zelkov 呂 Zelkova serrata ， camellia (Godfrey and Crowcrof t， 1960 ; Mellanby. 1971 ; Camellia japonica. J apanese cherry Prunus x yedoensis ， Gorman and Stone. 1990). and J apanese plum P. mume. In addition. the garden The fully fossorial lifestyle of the moles prevents contained several ground cover plants from the biologists biologists from observing their behavior. However. the Poaceae family (bristle grass Setaria viridis. zoysia development development of radio telemetry systems has allowed Zoysia japonica. and silver grasses Miscanthus spp.) and researchers researchers to study home range distribution. seasonal the forb guild (fleawort Plantago asiatica. dandelion changes changes in home range utilization ，and the relationship Taraxacum officinale. J apanese dock Rumex obtus ザolius. between home range size and habitat quality (Stone shepherd' s purse Capsella bursa-pastoris. and Cockleburs and Gorman. 1985 ; Gorman and Stone. 1990 ; Loy et Xathium spp.). These latter plants were mowed 2-3 al.. al.. 1992 ， 1994 ; Beolchini et al.. 1996). For example ，a times/year using a bush cutter. number of studies have shown that the home range of the the male European mole. Talpa europaea. does not Determination of depth use by the moles overlap overlap with other males. but does overlap with the Prior to the study ，we evaluated the relationship home ranges of several females. Furthermore ， female between transmitter signal strength and the depth of home ranges often overlap those of other females the transmitter below ground 目 The transmitters (50 (Stone (Stone and Gorman. 1985 ; Gorman and Stone. 1990) MHz ，Applied Biology. Co. Lt d.. J apan ; 144 MHz ， Gorman and Stone (1990) also showed that there was Arcitech Co. Lt d.. Japan) were buried at depths of 5. a negative relationship between food density and 30. 50. 100. and 150 cm. The radio signal was recorded territory territory size in the European mole. Interestingly. both using a receiver (FT -817. Vertex Standard Co.. Lt d.. the the pattern of home range overlap among individuals Japan) that was connected to a Yagi antenna (HY- and the relationship between food density and home 144. Natec Co.. Ltd.. Japan). The antenna was held range size is similar in the Roman mole. T. romana vertical to the ground and parallel to the body of the (Loy (Loy et al.. 1992. 1994 ; Beolchini et al. ， 1996). Loy et al. operator. We recorded the signal strength (S (1994) (1994) also observed patrolling behavior during the the radio signal emitted from the tags at each active active period and seasonal changes in home range We then used the S values to determine subterran 四日 utilization utilization in the Roman mole. depth of the moles during the study. These studies highlight the utility of radio telemetry for for evaluating the behavior of subterranean mammals Mole trapping and attachment of the transmitter However. few studies have evaluated seasonal changes We set mole live traps (Konishi type. Konishi in in depth utilization in moles. Our objective was to Factory Co.. Lt d.. J apan) in the center of the opening evaluate evaluate the seasonal changes in vertical distribution to each tunne l. The traps were checked at intervals of of of the lesser J apanese mole. M. imaizumii. This species 3-4 h and any moles that were captured were is is endemic to Japan and is found primarily in the east transported to the laboratory for tagging. We recorded area area of Honshu. Japan (Abe. 2005). We radio tagged the weight and sex (where possible). We evaluated several several individuals during a two year period and the reproductive state by checking for the presence of monitored their movement for up to two days. In an external generative organ in the males. Each mole addition. addition. we measured soil temperature and soil animal was then anesthetized using a combination of ether biomass at several depths to determine the gas and an injection of pentobarbital (Nembutal. relationship relationship between vertical distribution of the moles Dainippon Sumitomo Pharma Co.. Lt d.. J apan) or and soil temperature or prey abundance. ketamine (Ketalar. Daiichi Sankyo Co. ，Lt d.. J apan) . -156 Subterranean Subterranean spatial utilization of the lesser ]apanese mole ，Mogera imaiZllmii Once the animal was fully anesthetized ，we inserted a classified as inactive if the mole was stationary or th 記 microchip microchip (BioMedic Data Systems Inc" U. S. A.) S value was stable for > 15 min under the skin on the back of the mole for individual The home range size of each mole was estimated identification. identification. A radio transmitter was then glued to using a 100% minimum convex polygon. The areas of the the dorsal surface at the base of the tail and secured the study site that were inaccessible to the moles (e.g. with with surgical sil k. The area of attachment was shaved buildings) were removed from the calculation of home to to ensure the transmitter adhered to the body. The range size. The distance traveled by each mole was animal animal was then allowed to recover from anesthesia estimated by summing the linear distance between and was released at the point of capture consecutive records (5 min apart). Radio telemetry Soil temperature and vertical distribution of soil We recorded the highest S value reading every 5 min animals and marked the location using a numbered wooden We monitored soil temperature every h at depths of peg. peg. During the observations ，we attempted to hold 5，30 ，50 ，and 100 cm using thermal data loggers (RTR 】 the the antenna in the same manner as during the initial 51 ，T&D Co.