Winter Weight Loss in Japanese Serow

Abstract

To obtain winter weight loss patterns by sex and age, we examined whole weight data on 925 Japanese serows (Capricornis crispus) shot in Gifu and Nagano prefectures, Japan, during November-March in 1980-81 and 1981-82. Weight loss among yearling, juvenile, adult, and aged serows of both sexes ranged from 5 to 23%, whereas lambs did not lose much weight. Adults lost more weight during the severe winter than during the moderate winter. J. WILDL. MANAGE. 50(2):336-338 It is well documented that body weights of northern ungulates are heaviest in fall, decline over winter, and are lightest in early spring (Moen 1973, Anderson et al. 1974, Franzmann et al. 1978, Nichols 1978, Knaus and Schrider 1983). From winter until spring, metabolic rate and food intake decline, and these animals then are in a negative energy balance wherein they depend mainly on stored body fat for sustenance. Food availability and weather conditions during winter can directly affect mortality. A knowledge of seasonal changes in ungulate body weights is an important management consideration because such trends serve as an index of range nutritional status. As a part of a population study of Japanese serows we investigated their weight loss patterns by sex and age from late fall to early spring. These findings are reported here. We are deeply indebted to M. Sugimura of the Dep. Vet. Anat., Gifu Univ., for granting permission to report data collected by him and his staff. We thank K. Tokita, H. Saitoh, R. Higashi, and H. Higashi, Res. Cent. Jap. Wildl., and personnel of the Gifu and Nagano Gov. for their invaluable assistance. This work was supported in part by a Grant-in-Aid for Sci. Res. from the Minist. Educ., Sci., and Cult., Jap. STUDY AREA AND METHODS The collection area encompassed approximately 9,000 km2 along the Gifu-Nagano prefectural border which is located in the central part of Honshyu, Japan. Elevations range from 700 to 2,600 m. Topography in the area is dissected by rugged, steep drainages and mounta ns extending north and south. The vegetation is a mosaic of clearcut patch with dwarf bamboo (Sasa kurilensis); temperate deciduous forest with Siebold's beech (Fagus crenata); Erman's birch (Betula ermanii), and oak (Quercus spp.); and artificial forest dominated by Hinoki cypress (Chamaecyparis obtusa) and Japanese larch (Larix leptolepis). Serow density on some regions of the area estimated by a direct count of the number seen in 1981 varied from 1.2 to 6.5/km2 (K. Tokita, unpubl. data). Serows were shot by hunters during November March 1980-81 and 1981-82. Whole body weight of the 925 serows taken were obtained to the nearest 0.5 kg. The ages of all serows were determined from horn ring and cemenum annuli counts (Miura 1985) and by tooth replacement pattern (Miura and Yasui 1985). Because serows presumably are born from late May to early June (Sugimura et al. 1983), ages of study specimens were grouped into 5 classes: lamb (0.5-1.0), yearling (1.5-2.0), juvenile (2.53.0), adult (3.5-11.0), and aged (>11.5 years old). To obtain the seasonal weight change patterns by sex and age, we calculated mean weights by 10-day intervals during each month. Linear regressions and correlation coefficients were derived according to Moen (1973). This content downloaded from 157.55.39.144 on Wed, 07 Sep 2016 05:44:31 UTC All use subject to http://about.jstor.org/terms J. Wildl. Manage. 50(2):1986 SEROW WEIGHT Loss * Miura and Maruyama 337 RESULTS AND DISCUSSION Monthly records from 11 meterological stations in the study area indicated that the winter of 1980-81 was severe, with monthly maximum snow depth averaging 48.0 cm from December to March. The 1981-82 winter was more moderate, with monthly maximum snow depth averaging 9.6 cm. Differences in mean whole weights between the 2 years were found in females for 3 age classes. Female lamb, adult, and aged serows were heavier during the 2nd year than the 1st (P 0.05) between the slopes of regression lines for these age-sex classes. However, the intercept of the regression line for pregnant adult females differed from that of nonpregnant adults (P 0.05) in the slopes and intercepts of the equations, adult serows apparently lost more weight during the severe winter of 1980-81 (21.2% for males and 17.4% for females) than during the moderate winter of 1981-82 (13.6 and 13.8%, respectively). This might be due to food limitation because deep snow covered much of 70 MALES