Do Feed Plants Provide Sufficient Sodium, Calcium and Magnesium to Sika Deer in Japan? An Analysis Using Global Plant Trait Data.

Deficient minerals in overabundant populations could act as an attractant to cull sika deer (Cervus nippon). Because selective culling of female deer is reported to be effective in reducing sika deer populations, it is particularly important to clarify the differences in mineral requirements between males and females. Here, using global plant trait data and a published list of sika deer feed plants in Japan, we estimated whether feed plants provide sika deer sufficient sodium (Na), calcium (Ca) and magnesium (Mg), and compared the results between males and females. An analysis of 191 feed plant species suggested that feed plants can provide sufficient Mg, whereas sufficient Na and Ca is not always provided, especially when the intake is small or the deer large. Na deficiency was more intense for lactating females than males, suggesting that Na can be an effective attractant for selectively culling female deer. In summary, this study demonstrated that sika deer in Japan might require extra Na and Ca sources in addition to feed plants, and therefore these minerals could be useful for developing effective culling methods.

A 17-Year Study of the Response of Populations to Different Patterns in Antlerless Proportion of Imposed Culls: Antlerless Culling Reduces Overabundant Deer Population.

Increasing populations of large herbivores have caused environmental damage around the world, and it is necessary to improve population management strategies. Culling is a traditional management method. Antlerless deer proportions, consisting of adult female deer and fawn in Cervidae in wildlife statistics, are directly related to population increases; thus, the culling-based removal of individuals from habitats and the removal of these antlerless individuals by game hunting and nuisance control might be effective approaches for reducing population sizes. We evaluated the effectiveness of antlerless culling on 17-year density trends in the sika deer (Cervus nippon) population across an area of 1175 km2 in Fukuoka Prefecture (Japan). In 11 out of 47 grids (area measuring 5 by 5 km), the densities of sika deer tended to decline; meanwhile, in the remaining 36 grids, the densities increased. These density trends were explained by changes in the proportion of antlerless culling, as the densities declined with increasing proportions of antlerless deer. The results affirm the theory that antlerless culling is effective in population management; it is posited that antlerless-biased culling could be a crucial measure in managing overabundant populations of herbivores, contributing to more effective conservation of forest environments.

FECAL PROGESTERONE METABOLITES IN POSTPARTUM SIBERIAN FLYING SQUIRRELS.

The Siberian flying squirrel ( Pteromys volans) produces up to two litters a year. To deliver second litters in breeding season, P. volans may have a postpartum estrus similarly to that of a variety of small mammals. If this were the case, females would have periods of elevated progesterone levels because of the formation of corpora lutea (CL) after postpartum ovulation. To test this hypothesis, fecal progesterone metabolite dynamics was investigated during lactation in this species using an enzyme immunoassay. In five of the six lactating females, periods of high fecal progesterone metabolite concentration were observed, and, furthermore, progesterone secretion patterns were periodic. Therefore, the source of progesterone during lactation could be arising CL from postpartum ovulation, indicating that ovarian activity was reinitiated after parturition and the CL that formed began secreting progesterone. This study thus showed that P. volans likely has the physiologic potential to mate during lactation.

Seasonal changes in activity patterns of Japanese flying squirrel Pteromys momonga.

Seasonal changes of activity patterns are an important survival strategy for several species. Seasonal changes in the activity patterns of Japanese flying squirrels (Pteromys momonga) were studied at Daibosatsu Mountain on Honshu Island, Japan from 2 June to 20 November 2007 and 11 April to 14 November 2008, to discuss their survival strategy based on the change. Activity patterns were assessed using long-term sensor camera traps at 214 sites for 14 months of a 2-year period. The cameras were placed for a total of 7317 camera trap nights over which total of 90 photographs of this species were collected from 22 of the 214 sites. Although distinct nocturnal activity was detected throughout the study period, activity patterns differed between temperate (June-September) and cold (April, May, October, and November) seasons. So, activity peaks were found to be bimodal during the temperate seasons and trimodal during the cold seasons. It is possible that the squirrels reduce their activity times per bout during the cold seasons to reduce energy loss arising from prolonged exposure to cold temperatures, as a survival strategy.