Masked Palm Civet Paguma Larvata Summer Diet Differs Between Sexes in a Suburban Area of Central Japan
Total Page:16
File Type:pdf, Size:1020Kb
Mammal Study 42: 185–190 (2017) © The Mammal Society of Japan Short communication Masked palm civet Paguma larvata summer diet differs between sexes in a suburban area of central Japan Masakazu Iwama1, Koji Yamazaki2,6, Miho Matsuyama3, Yoshinobu Hoshino3, Masumi Hisano4, Chris Newman5 and Yayoi Kaneko1,* 1 Carnivore Ecology and Conservation Research Group, Institute of Agriculture, Tokyo University of Agriculture and Technology, Saiwaicho 3-5-8, Fuchu, Tokyo 183-0054, Japan 2 Ibaraki Nature Museum, Zoological Laboratory, 700 Osaki, Bando, Ibaraki 306-0622, Japan 3 Laboratory of Vegetation Management, Institute of Agriculture, Tokyo University of Agriculture and Technology, Saiwaicho 3-5-8, Fuchu, Tokyo 183-0054, Japan 4 Faculty of Natural Resources Management, Lakehead University, 955 Oliver Road, Thunder Bay, ON P7B 5E1, Canada 5 Wildlife Conservation Research Unit, Department of Zoology, University of Oxford, The Recanati-Kaplan Centre, Tubney House, Abingdon Road, Tubney, Oxon OX13 5QL, UK 6 Department of Forest Science, Faculty of Regional Environmental Science, Tokyo University of Agriculture, 1-1-1 Sakuragaoka, Setagaya, Tokyo 156-8502, Japan Abstract. We studied the summer (June–August) diet of the masked palm civet (Paguma larvata) in a suburban area of Ibaraki Prefecture, using the stomach contents from road-killed carcasses. Specifi- cally, our aim was to examine (i) monthly changes and (ii) if food habits differed between sexes, based on frequency of occurrence (FO) of the main food classes consumed. From 2009 to 2014, 61 civet carcasses were collected along the three major national highways in Ibaraki Prefecture. Civets con- sumed a wide range of foods such as insects, fruits, mammals, and earthworms. The FO of mammals and fruit taxa (cherries, strawberries, and persimmons) differed substantially among months, which likely reflected the peak availability of each food category/item. Females consumed amphibians, insects, and persimmons significantly more frequently than did males, likely relating to the higher food security demands of females while raising offspring. Overall, masked palm civets in Ibaraki Prefecture proved to be opportunistic and generalist feeders, eating primarily fruits and insects with a high fre- quency of occurrence in summer. Key words: diet, frugivory, human-wildlife conflict, sexual size dimorphism, stomach contents. The masked palm civet (Paguma larvata, hereafter In their native range (in subtropical central China; “civet”) occurs widely across South Asia, Southeast Asia, Zhou et al. 2008), the civet diet is comprised mainly by China, and Taiwan (Torii 2009); although it is now gen- wild/cultivated fruits and small mammals/birds; subject erally recognised to be an introduced species in Japan. to dietary shifts in accord with seasonal changes in fruit Since the first civet was recorded in Japan (1940s) their availability. In Japan, the food habits of the civet have range has expanded substantially (currently to 43 of 47 been examined in Shizuoka Prefecture (Shizuoka Prefec- prefectures; Ministry of Agriculture, Forestry and Fisheries ture 1996), Chiba Prefecture (Matsuo and Ochiai 2009), Japan 2008). This invasion causes a human-wildlife con- Gunma Prefecture (Anezaki et al. 2010), and in Tokyo flict (Woodroffe et al. 2005); civets cause considerable (Yoshino and Hagiwara 2010). While these studies crop damage, amounting to 433 million yen (approxi- describe that civets rely primarily on fruits, they also mately 4.5 million US dollars) in 2012 (Ministry of Agri- highlight that civets can feed opportunistically on other culture, Forestry and Fisheries Japan 2012). A better foods such as arthropods, molluscs, fish, reptiles, and understanding of the civets’ diet is therefore crucial for scavenged items. their effective management. Differences in prey preferences between the sexes have *To whom correspondence should be addressed. E-mail: [email protected] 186 Mammal Study 42 (2017) been observed in various small carnivores (Boydston et al. 2001), notably mustelids (e.g., Mustela spp. Moors 1980; Birks and Dunstone 1985; Dayan et al. 1989). This has been attributed to sexual size dimorphism (Moors 1980), where either: (a) larger males tend to hunt larger prey than do smaller females (e.g., Brown and Lasiewski 1972); or (b) females need greater food security than males to raise their offspring and select home ranges to ensure sufficient food availability (e.g., Moors 1980), whereas males organise their territories not only based on food, but also to overlap breeding females, leading to them utilizing a more extensive range (Greenwood 1980; Fig. 1. Locations from which masked palm civet carcasses were Kaneko et al. 2014; Noonan et al. 2016). Although civets collected in Ibaraki Prefecture. are polygynandrous and sexual size dimorphism is not evident (see Ohdachi et al. 2009), male home ranges of small areas of farmland (58.4%), forest (19.2%), urban (276.8 ± 77.4 ha) in central China tend to be twice as development (18.0%), wetland (1.9%), orchard (1.3%), large as those of females (136.5 ± 38.3 ha) (Zhou et al. and other habitat (1.2%), as well as two medium-sized 2014). This socio-spatial organisation may interact with cities (Mito and Hitachi—with an averaged population their preferred prey selection (see also Zalewski 2007). density of 1036.6/km2, January 2009; Hitachi City 2010; Our study was conducted in an area of mixed suburban Mito City 2010). Forests mainly consisted of plantations housing and agricultural land in Ibaraki Prefecture Japan. of Japanese cedar (Cryptomeria japonica), Japanese Civets were first confirmed in Daigo town, in the northern cypress (Chamaecyparis obtusa), Japanese red pine part of Ibaraki Prefecture, in 1963 (Yamazaki et al. 2001) (Pinus densiflora), sawtooth oak (Quercus acutissima), and then reached the southern part of the prefecture by the and konara oak (Q. serrata). Japanese pears (Pyrus 1990s (Yoshitake 1998). Given their opportunistic feed- pyrifolia var. culta), Japanese chestnuts (Castanea ing habits (Zhou et al. 2008), we posited that civets would crenata), Japanese apricots (Armeniaca mume), persim- consume the widest range of food items in the summer mons (Diospyros kaki), and grapes (Vitaceae spp.) were months when fruits and invertebrates are readily available widely cultivated in orchards. (although some persimmons and oranges are also grown Between 2009 and 2014, we collected 118 civet road in the winter). Indeed, records of civets killed along a kills from the three major national highways transecting major highway in this region (Ibaraki Nature Museum, Ibaraki Prefecture (Routes 6, 50, and 51, with a total unpublished data) imply that civets are most active in the length of ca. 323 km; Fig. 1). Sixty-one of these casualties summer, with 46.7% (50 of 107) of road-killed civets occurred in summer (June–August), 28 in spring (March– recovered over just the three months (June–August May), and 23 in autumn (September–November); only between 2004 and 2013). In this first investigation of this six were recovered in winter (December–February), type for this species, and focusing on this summer period, which was insufficient to support statistical analysis. here we aimed to: (i) describe the general summer diet of From these, we collected stomach contents samples from the civets by analysing stomach contents, and (ii) exam- those civets killed during the summer, to coincide with ine differences in food habits between sexes. the ripening season of vulnerable crops. Carcasses were stored (at –25°C to –30°C) at the Ibaraki Nature Museum Materials and methods prior to necropsy and the dissection of stomach contents. Stomach content samples were then either preserved in Study area and sample collection 80% ethanol (2009–2013) or frozen (–15°C; 2014) until This study was conducted in the northern and central dietary analysis. All 61 carcasses (29 males and 32 parts of Ibaraki Prefecture (area ca. 437 km2), which lies females) were adult, where maturity was determining by in the north-eastern part of the Kanto Plain (Fig. 1). The head-body length exceeding 440 mm, following Torii mean human population density over this prefecture was (2009), who determined that, in the Shizuoka population, 476.8/km2 in 2016 (according to the Ibaraki Prefectural civets over 469 mm were >2 years old. Government 2016). This landscape comprised a mosaic Iwama et al., Summer diet of palm civets 187 Dietary analysis food categories and fruit items over the three summer Stomach content examination was performed follow- months, and to test for differences between the sexes. If a ing the methods of Matsuo and Ochiai (2009), and refer- significant (a = 0.05) monthly difference was detected, ring to Fukue et al. (2011). Stomach contents were washed we then conducted post-hoc pairwise Fisher’s exact tests through a 0.5-mm-mesh sieve with 1 L water. Food items with Bonferroni correction to determine in which month were classified into 14 categories (that is, these ‘items’ civets consumed these items most frequently (Tsuji et al. comprised ‘categories’): ‘mammals’, ‘birds’, ‘reptiles’, 2014; Hisano et al. 2017). For the Bonferroni post-hoc ‘amphibians’, ‘fish’, ‘insects’, ‘crustaceans (crabs and test, the statistical significance standard (a) was adjusted shrimps)’, ‘molluscs (slugs and snails)’, ‘earthworms’, to 0.017 (i.e., 0.05/3 months). All statistical analyses were ‘other animals (e.g., centipedes or spiders)’, ‘unidentified conducted using R 3.2.4 (R Development Core Team animals’, ‘berries and seeds’, ‘other plants (i.e., grasses, 2016). twigs, plant galls)’, ‘artificial materials (i.e., human- subsidised food, garbage, plastic, vinyl)’, along with inci- Results dental items such as own hairs, inorganic materials, and unidentified items, which were excluded from the analy- General summer diet sis. We identified seeds present up to the species level. Across all five years, on average individual civets con- We also examined the residual water used for washing sumed foods from 4.26 ± 1.16 categories (range 1–7), stomach contents, to count any earthworm chaetae excluding unidentified food.