Hokkaido Sika Deer Research Articles

Evaluation of GPS telemetry and its application for Hokkaido sika deer

Evaluation of GPS telemetry and its application for Hokkaido sika deer

Seasonal fluctuations of body condition in northern sika deer on Hokkaido Island, Japan

We analyzed seasonal and sexual fluctuations in kidney mass (KM) and kidney fat mass (KFM) as indices of condition in Hokkaido sika deerCervus nippon yesoensis Heude, 1884. For 76 male and 132 female sika deer, seasonal fluctuations in KM and KFM were given by fitted sine wave growth curves. Although the kidney fat index (KFI) is used frequently to evaluate animal condition, we reject it because it is based on the assumption that kidney mass is proportional to body mass in all seasons. Our data did not support this assumption. KFM is a better indicator of Hokkaido sika deer condition than KFI. Although sex-based differences in cervid KFM are said to reflect differences in reproductive cycles, the seasonal similarities in sika deer KFM levels may represent adaptations to the long severe Hokkaido winter. Because in our study deer populations were at low densities and had high pregnancy rates, our sine wave growth models can be regarded as reference for fat level fluctuations in Hokkaido sika deer.

Expression of prolactin receptor (PRL-R) mRNA in the caudal gland of Hokkaido sika deer (Cervus nippon yesoensis Heude, 1884)

We applied the in situ hybridization technique to the Hokkaido sika deer (Cervus nippon yesoensis) caudal glands using probes designed from the red deer (Cervus elaphus) prolactin receptor cDNA. Prolactin receptor mRNA expression was consistently detected in the secretory epithelial cells collected from fawns and lactating hinds. This suggests that the presence of developed caudal glands during late pregnancy and lactation may be caused by increased blood levels of prolactin. During late pregnancy and lacation, visual range is limited for deer in forests and grasslands because of the flourishing leaves and sprigs. Therefore, we suggest that the scent emitted from the caudal gland in a particular season coordinates with and reinforces the visual alarm effect of the rump patch and tail.

Population size estimation and feedback management of Sika deer in Hokkaido(SPECIAL LECTURE)

Population size estimation and feedback management of Sika deer in Hokkaido(SPECIAL LECTURE)

Body size, sexual dimorphism, and seasonal mass fluctuations in a larger sika deer subspecies, the Hokkaido sika deer (Cervus nippon yesoensis Heude, 1884)

Measurements of shoulder height, body length, hind-foot length, and total body mass were collected from 309 Hokkaido sika deer (Cervus nippon yesoensis Heude, 1884) (115 males and 194 females) and analyzed statistically for sexual dimorphism and seasonal body mass fluctuations. The von Bertalanffy equation was fitted to the growth curves that resulted. Asymptotic shoulder height, body length, and hind-foot length were 106.2, 112.6, and 52.9 cm in males and 94.8, 103.9, and 49.4 cm in females, respectively. Total body mass showed distinct seasonal fluctuations, ranging between 102.8 and 151.0 kg in adult males and 68.0 and 99.8 kg in adult females. Male/female ratios in shoulder height, body length, hind-foot length, and total mass were 1.12, 1.08, 1.07, and 1.51, respectively. These results indicate that the Hokkaido sika deer is one of the largest subspecies, at least in skeleton size. A larger body and longer hind foot would seem to be evolutionary adaptations to Hokkaido's cold, snowy environment.

Spatial distribution of Hokkaido sika deer and its hunting area

Spatial distribution of Hokkaido sika deer and its hunting area

Seasonal movements of female sika deer in eastern Hokkaido, Japan.

Seasonal movements of 16 female sika deer (Cervus nippon) were monitored using radio telemetry from April 1993 through June 1996 in eastern Hokkaido. Fifteen of these deer migrated between summer and winter ranges, and one was killed during the hunting season, before we could determine its migratory habits. Timing of spring migration coincided with snow-melt in April and May. Snow cover also influenced the timing of autumn migration, but its effects were less clear. Distances traveled from winter to summer ranges averaged 19.9 km (n=22) and maximum distance was 42.0 km. Deer showed high fidelity to summer ranges; all 9 females that were monitored more than 12 months used the same summer range in consecutive years. Fidelity to winter ranges was less apparent. Distances between consecutive winter ranges used by individual deer averaged 5.0 km (n=10) and those between consecutive summer ranges averaged 0.6 km (n=10).

Chemical prevention of Larix leptolepis stands from damage by sika deer (Cervus nippon yezoensis) in Hokkaido

Chemical prevention of Larix leptolepis stands from damage by sika deer (Cervus nippon yezoensis) in Hokkaido

Gestational age determination, variation of conception date, and external fetal development of sika deer (Cervus nippon yesoensis Heude, 1884) in eastern Hokkaido.

The authors determined gestational age from fetal weight, examined the range in conception dates, and classified the external fetal development process in sika deer of eastern Hokkaido. Gestational age (T) can be estimated from fetal weight (W) with the equation: T = (3 square root of W + 2.730)/0.091. Conception date can then be calculated back from date of kill of pregnant female, using gestational age. Though estimated conception dates ranged from 7 October to 17 January, most of them were concentrated between mid October and early November. In late November and after, nine conceptions were observed and six out of the nine late cases occurred in yearling females. This phenomenon is probably due to the excellent nutritional condition of deer in the study areas, which allows yearling females to mature sexually even in early winter. In fetuses, periods of tactile hair development, appearance of white spots, and development of general hairs overlap very little. In addition, these developmental changes occur at specific fetal weights. Based on these external phases, the gestation period can be divided into four stages. These stages will be useful for simple determination of fetal age in various sika deer populations.

New field signs in Sika deer in Hokkaido

New field signs in Sika deer in Hokkaido