Differences in Habitat Use of the Native Raccoon Dog (Nyctereutes

Differences in habitat use of the native raccoon dog (Nyctereutes procyonoides albus) and the invasive alien raccoon (Procyon lotor) in the Nopporo Natural Forest Park, Hokkaido, Japan

Go Abe, Tohru Ikeda and Shirow Tatsuzawa Department of Regional Sciences, Faculty of Letters, Hokkaido University, N10-W7 Kita-ku Sapporo 060-0810, Japan

Abstract We investigated differences in home range sizes and in the pattern of habitat use between the raccoon (Procyon lotor), an invasive alien species, and the native raccoon dog (Nyctereutes procyonoides albus), which lived sympatrically in Nopporo Natural Forest Park, Hokkaido, Japan. The mean home range size of raccoons (±2SD) was 116.2ha (±203.8ha), and that of raccoon dogs was 125.2ha (±71.1ha). The mean size of core areas was 12.1ha (±18.4ha) for raccoons, and 10.6ha (±12.8ha) for raccoon dogs. There were no significant differences between these two species in home range size (U-test, p=0.571) or in core areas (U-test, p=0.571). The pattern of habitat use, however, differed between these two species. Diurnal resting sites were located in woodland margins for raccoons, but in woodland for raccoon dogs. A comparison of the utilisation rates of farm fields in the home range showed that raccoons used farm fields significantly (U-test, p<0.05) more than raccoon dogs. This result supports that in Japan raccoons use farmer’s properties for feeding and breeding.

Keywords: raccoon; raccoon dog; pattern of habitat use; invasive alien species; home range; radio-tracking

INTRODUCTION

The irresponsible breeding and release of pet raccoons Hokkaido, Japan. (Procyon lotor Linnaeus, 1758) in Japan, coupled with their rapid naturalisation, has caused this species to pose problems to native habitats and biodiversity METHODS (Ikeda 2000). Raccoons naturalised 28 years ago in Hokkaido and dispersed to more than half of its Study area municipalities. Now, their number is estimated to be over three thousand in the central part of the island The study was conducted in the Nopporo Natural (Hokkaido Prefecture 2003). Severe damage to crops Forest Park, located 11 - 15km east of the City of and predation on endangered species such as the Sapporo (43'25"N, 141'32"E), central Hokkaido, Japan. Japanese crayfish (Cambaroides japonicus) have been This is a 2,040ha sub-isolated forest (ca. 6×4km), with reported (Hori and Matoba 2001, Ikeda et al. 2004). altitudes between 20 to 100m above sea level. The The raccoon dog (Nyctereutes procyonoides albus annual precipitation and the mean temperature are Beard, 1904) is a native carnivore of Family Canidae in 899mm and 6.6ºC (-25.8ºC in February and up to Japan, whose body size (Kinoshita and Yamamoto 29.8ºC in August), respectively (Data from Japan 1996, Kishimoto et al. 1998, Zeveloff 2002, Asano Meteorological Agency). This forest is a mixed 2003b), breeding season (Ikeda 1983, Asano 2003a), conifer-hardwood forest, dominated by Abies seasonal activity patterns (Yamamoto 1993, Kurashima sachalinensis, Acer mono, Quercus mongolica var. grosserrata, et al. 1998) and diet (Hori and Matoba 2001, Furukawa and Fraxinus mandshurica var. japonica (Ishikawa 1989). 2001, Kasuya 2001) are similar to those of the feral The presence of raccoons was first verified in this raccoon Small animals and fruits are major food forest in 1992 (Kadosaki 1996). Subsequently, they sources for both species. The impact of raccoons on have been suspected of serious agricultural damage the native raccoon dogs is important and it is a and attacks on a colony of herons (Ardea cinerea) inside frequently debated issue in nature conservation in the forest (Ikeda 1999, Hokkaido Prefecture 2003). Japan. They are very attracted to crops like sweet corn, Raccoons are known to live sympatrically with melons and strawberries. During the study period, only raccoon dogs in Hokkaido, but information about the strawberries were ripening in and around the research relationship between these two species is still fields. incomplete. In the present study we report on the differences in the pattern of habitat use between these Trapping and radio-collaring two sympatric nocturnal carnivores, during daytime and night-time, in Nopporo Natural Forest Park, Traps were set for 48 days in total, from 26 March to

Pages 116-121. In Koike, F., Clout, M.N., Kawamichi, M., De Poorter, M. and Iwatsuki, K. (eds), Assessment and Control of Biological Invasion Risks. Shoukadoh Book Sellers, Kyoto, Japan and IUCN, Gland, Switzerland, 2006. G. Abe et al.

year (Maesaki et al. 2002). Live cage traps (model #1089: 82Lx27Wx30H cm; ca 4.0kg; Havahart, Litiz, Pennsylvania, USA) were used, baited with dog food, corn snacks and doughnuts. We set traps at intervals of about 500m, which was smaller than the raccoon's home range length reported by Kurashima and Niwase (1998). We estimated that this distance is the potential trapping radius for each trap (Fig. 1). On their first capture, trapped raccoons and raccoon dogs weighing 3.5kg or more were immobilised with an intramuscular injection of ketamine hydorochloride (Ketaral, 1mg/kg), medetomidine hydrochloride (Domitor, 40µg/kg) and midazolam (Dormicam, 0.15mg/kg). Body mass, head-body length and tail length were measured and radio-collars were fitted (ca 120g, ATS, Inc., USA). After finishing these procedures, the reversal agent

potential trapping radius atipamezole hydrochloride (Antisedan, 40µg/kg) was trap point (500m) administered, assisting recovery. Animals were released drive way farm field at the site of capture after approximately two hours, by heavy traffic road woodland which time they had fully recovered from the river residential area anaesthesia. Figure 1 Nopporo Natural Forest Park and the adjacent Juvenile individuals of less than 3.5kg and areas. This park is wedged between the north-western individuals suspected to be suffering from sarcoptic residential area and the south-eastern farm fields. We set mange (Sarcoptes scabie Linnaeus, 1758) were not a maximum of 34 traps in the southern part of the park collared, for animal welfare reasons. and estimated the potential trapping radius of each trap as 500m. The dashed line shows the research target area,

where the home ranges of some raccoons and raccoon dogs were thought to overlap. Radio-tracking

From June to July in 2003, we recorded telemetry 24 May 2003 (except for 23 - 29 April and 6, 7, and 14 locations for all radio-collared individuals once a day in - 16 May), using a maximum of 34 traps (25 days for the daytime, between 0700 - 1800. As both raccoons each trap; 851 Trap-nights; Fig.1) in the southern part and raccoon dogs are nocturnal (Mech et al. 1966, of Nopporo Natural Forest Park, where both species Yamamoto 1993), we assumed that these location had been trapped most frequently during the previous points represented their resting sites. We radio-tracked

Table 1 Radio-collared raccoons and raccoon dogs, both of which were captured in Nopporo Natural Forest Park, Hokkaido in May, 2003. All individuals in the table were radio-tracked during the daytime, and those with asterisks were also radio-tracked at night. The “head body” was larger estimation since we measured the length along the curve of neck. Body length Head Body + tail Body mass Radio-tracking Species ID Sex length (kg) at night (cm) r-f1 female 64.0 + 28.0 6.0 * r-f2 female 61.0 + 31.0 8.0 * r-f3 female 63.0 + 25.0 4.4 * r-f4 female 62.5 + 31.0 5.7 Raccoons r-f5 female 64.0 + 23.5 6.4 (Procyon lotor) r-f6 female 62.0 + 28.0 5.6 r-f7 female 54.0 + 24.0 4.3 r-f8 female 62.0 + 28.0 5.4 r-m1 male 60.0 + 26.0 4.2 * rd-f1 female 56.7 + 17.0 5.6 * Raccoon dogs rd-f2 female 51.0 + 16.0 4.3 * (Nyctereutes rd-f3 female 54.0 + 16.0 3.5 procyonoides albus) rd-f4 female 58.0 + 21.0 3.8 rd-m1 male 57.0 + 18.0 3.8 *

117 Habitat use of native raccoon dogs and alien raccoons particular individuals whose nocturnal home ranges RESULTS were assumed to overlap with each other (based on the fact that their resting sites overlapped). This Trapping and radio-tracking radio-tracking at night was done every hour between 1800 - 0700, once per week. Nine raccoons (one male and eight females) and nine Radio signals were detected with a hand-held raccoon dogs (one male, five females, and three of four-element Yagi antenna and receiver (FT290, unknown sex) were trapped and all nine raccoons and YAESU, Japan). Azimuths were triangulated from at five raccoon dogs (one male and four females) were least three positions to fix a location. radio-collared. One female raccoon dog weighing less than 3.5kg and three other raccoon dogs suspected to be suffering from sarcoptic mange were not collared. Data analysis Based on the telemetry location data for resting sites, we selected four raccoons (one male and three To examine only the nocturnal activities of raccoons females) and three raccoon dogs (one male and two and raccoon dogs, which live sympatrically, we females), because they were assumed to have home compared location data of individuals monitored for ranges overlapping with the other species. The home more than three nights. Home ranges as well as core ranges of other radio-collared individuals (five areas that each animal used frequently were calculated raccoons and one raccoon dog) did not have such based on the whole nocturnal activity pattern for each overlapping at all (see details on Tab. 1 and Figs. 2 and individual. Their home ranges were estimated with the 3). 100% Minimum convex polygon method and the core We obtained 355 locations for the four raccoons areas were estimated with the 50% Fixed Kernel and 247 locations for the three raccoon dogs for method (Worton 1989), which calculated the utilisation nocturnal activities. Radio transmitter signals stopped distribution as a grid coverage using ad hoc calculation for one female raccoon and one female raccoon dog in of a smoothing parameter. For these analyses, Animal July. Due to insufficiency of data, we therefore omitted Movement ver. 2.0 (Hooge and Eichenlaub 1997), and the July data from our analyses. the add-in software of ArcView (Esri Inc., Redlands, California, USA) were used. We examined the statistical significance of Home range size differences in size of home range, core area, and utilisation rates of farm fields, using Mann-Whitney's Fig. 4 shows the nocturnal activity patterns of four U-test (p<0.05). raccoons (one male and three females) in the early

rd-m1

r-m1

drive way farm field resting site drive way farm field resting site heavy traffic road core area heavy traffic road woodland woodland core area river river residential area residential area Figure 3 Resting sites and core areas of five Figure 2 Resting sites and core areas of nine raccoons raccoon-dogs obtained from diurnal radio-tracking in obtained from diurnal radio-tracking in Nopporo Nopporo Natural Forest Park, in June and July 2003. Natural Forest Park, in June and July 2003. r-m1 rd-m1 represents a male raccoon-dog. represents a male raccoon.

118 G. Abe et al. summer of 2003, while Fig. 5 shows those of three areas both inside and outside of the woodland. raccoon dogs (one male and two females) for the same Raccoon dogs, however, stayed inside the forest and duration. The mean nocturnal home range size of the rarely used farm fields during the study periods (Fig. 5). raccoons (±2SD) was 116.2ha (±203.8ha), whereas Raccoons used the farm fields significantly (U-test, that of the raccoon dogs was 125.2ha (±71.1ha). The p<0.05) more than raccoon dogs (see details in Tab. 2). mean size of nocturnal core areas was 12.1ha (±18.4ha) for the raccoons and 10.6ha (±12.8ha) for the raccoon dogs. There were no significant DISCUSSION differences between the two species in either home range size (U-test, p=0.571) and in the size of core This study revealed different habitat use between areas (U-test, p=0.571). raccoons and raccoon dogs despite their sympatric The diurnal resting sites and core areas indicated co-existence. Both raccoons and raccoon dogs had den sites and breeding nests. Both species had plural several daytime resting sites, but raccoons seemed to resting sites, but the number of core areas was be less fixed to a particular den site than raccoon dogs. different between raccoons and raccoon dogs. While It has previously been reported that raccoons seven out of eight raccoons had several core areas, frequently shift diurnal resting sites, particularly when three out of four raccoon dogs had a single diurnal they are using dens on the ground during summer and core area during the study periods (Figs. 2 and 3). autumn (Mech et al. 1966, Shirer and Fitch 1970). Fritzell (1978) observed raccoons in North Dakota rarely reusing daytime resting sites on successive days. Habitat use Gehrt (2003) supposed that this might partially be because raccoons had a large home range, as this The pattern of habitat use differed between these two makes it more difficult to return to a previous resting species. Resting sites and core areas of raccoons in the site. It was not clear whether raccoons in the present daytime were mostly located on woodland margins, study used dens on the ground, but the size of their except for one male raccoon (r-m1) occupying a home ranges was as large as reported elsewhere, where farmer's barn in July of 2003 (Fig. 2). By contrast, all sizes from 50 to 300ha were given (reviewed by Gehrt of the resting sites of raccoon dogs were located (2003)). within woodland areas (Fig. 3). Raccoon dogs in Honshu, the main island of In nocturnal activities, raccoons went out of the Japan, have several daytime resting sites in their home forest frequently and sometimes crossed a road with ranges (Yamamoto. 1993). Although raccoon dogs in heavy traffic (Fig. 4). Three of them had multiple core the present study also had some daytime resting sites,

r-f1 rd-m1 r-f2 rd-f1

r-f3

r-m1 rd-f2

drive way farm field home range drive way farm field home range heavy traffic road woodland heavy traffic road woodland core area resting site river residential area river residential area

Figure 4 Nocturnal home ranges and core areas of four Figure 5 The home ranges and the core areas of three raccoons radio-tracked in Nopporo Natural Forest Park, raccoon-dogs radio-tracked at night in Nopporo Natural for two months from June to July 2003. r-m1 represents a Forest Park, June and July 2003. rd-m1 represents a male male raccoon. Home range and core area of each raccoon-dog. Home range and core area of each individual are shown with specific line pattern. individual are shown with specific line pattern.

119 Habitat use of native raccoon dogs and alien raccoons

Table 2 Sizes of nocturnal home ranges and core areas of raccoons and raccoon dogs radio-tracked in Nopporo Natural Forest Park, Hokkaido, June to July 2003. Percentage area of farm field areas in home range and core area are shown. Home range, 100% MCP1 Core areas, 50% FK2 Species ID Area (ha) Farm-field (%) Area (ha) Farm field (%) r-f1 161 74 25 43 Racoons r-f2 59 35 6 37 (Procyon lotor) r-f3 236 52 14 88 r-m1 9 63 5 52 Raccoon dogs rd-f1 85 27 3 11 (Nyctereutes rd-f2 153 0 14 0 procyonoides albus) rd-m1 138 15 14 36 100% MCP1 : 100% Minimum Convex Polygon method, 50% FK2 : 50% Fixed Kernel method. they were also fixed on the use of a particular breeding this study is representative for raccoon dog behaviour site. In raccoon dogs, both the male and female in Hokkaido, this would be clearly different from their participate in pup rearing (Ikeda 1983, Yamamoto behaviour in Honshu. 1987, Kauhala and Saeki 2003), and take turns to The difference in habitat use between these two attend the den for 30 to 50 days after the breeding. species also evokes the possibility of direct and/or (Fukue 1991, Saeki 2001). In Japan, the breeding indirect inter-specific competition. Although the season of raccoon dogs is reported to be from April to present study, however, does not provide any evidence June. Our study period, June to July, is supposed to be of competition, ongoing monitored video camera part of the pup rearing season, thus individuals might recordings could clarify this possibility, as raccoons have been fixed on particular dens. visited the dens and latrine sites of raccoon dogs. Raccoons used areas of farm fields more than Unfortunately, small sample sizes limited the scope for raccoon dogs. It is well-known that raccoons utilised detailed analysis of dynamic interactions between farmer's barns for feeding and breeding in Japan raccoons and raccoon dogs, but we showed that the (Ando and Kajiura 1985, Maesaki et al. 2002, Ikeda et al. habitat use between these two carnivores was different, 2004). Ikeda (1999) reported that these buildings could even though they live sympatrically. have helped the introduced raccoons to naturalise in Hokkaido through the cold winter. In their native range in North America, raccoons ACKNOWLEDGEMENTS prefer to live near the water or moderately moist environments such as hardwood and mangrove We wish to thank all the students who assisted our swamps, marshes, and bottomland forests (Stuewer trapping, anesthetising and radio-tracking in this study. 1943, Zeveloff 2002), because much of their diet is We are also grateful to Nopporo Natural Forest Park sourced from aquatic areas (Stuewer 1943, Lotze and Office and the Nature Preservation Division of the Anderson 1979, Sanderson 1987). In our study area Hokkaido Government which supported our study. there are many streams running through the woodland Especial thanks to Dr. Asano (United Graduate School to the farm fields, although small streams are not of Veterinary Sciences, Gifu University), who gave us shown in our map (Fig. 1). It is also known that precise advice on anaesthesia. This study was raccoons can thrive in a wide variety of habitats in supported by the Ministry of the Environment as a their native range. They commonly live in suburban Global Environment Research Programme (F3: 2002 - residential areas and on cultivated and abandoned farm 2004). fields (Zeveloff 2002). By contrast, the raccoon dogs in our study area tended to stay inside the forest during the daytime as REFERENCES well as the night-time, even if their core areas were in marginal woodland areas. This result is consistent with Ando, S. and Kajiura, K. 1985. The habitat situation of Procyon lotor in Gifu Prefecture. Bulletin of the Gifu Prefectural Museum. the fact that local people are often unaware of raccoon 6: 23-30. (in Japanese) dogs being in the adjacent forests. Asano, M., Matoba, Y., Ikeda, T., Suzuki, M., Asakawa, M. and In Honshu, not much information on the feral Ohtaishi, N. 2003a. Reproductive characteristics of the raccoon is available, compared with information on feral raccoon (Procyon lotor) in Hokkaido, Japan. J. Vet. the raccoon dog, which is one of the most popular Med. Sci. 65(3): 369-373. Asano, M., Matoba, Y., Ikeda, T., Suzuki, M., Asakawa, M. and mammals due to its frequent appearances in residential Ohtaishi, N. 2003b. Growth pattern and seasonal areas (Yamamoto et al. 1995, Sonoda and Kuramoto, weight changes of the feral raccoon (Procyon lotor) in 2001), rice fields, croplands and abandoned fields Hokkaido, Japan. Jpn. J. Vet. Res. 50(4): 165-173. (Teduka et al. 1999, Sonoda 2001, Kauhala and Saeki Fritzell, E.K. 1978. Habitat use by prairie raccoons during the waterfowl breeding season. Journal of Wildlife 2004). Thus, if the tendency of the raccoon dogs in Management. 42: 118-127.

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