A simple method for calculating minimum estimates of previous population sizes of wildlife from hunting records

Hunting records have proven useful for examining the historical status of wildlife populations. The number of animals harvested can provide information on past population sizes that would have been required to support harvest yields. Therefore, when statistical data on annual harvests are available, a minimum estimate of past population sizes can be calculated. A very simple method for estimating the sizes of historic wildlife populations using only annual hunting records and the maximum annual population increase rate is presented in this study. This method was applied to estimate past population sizes for Japanese sika deer (Cervus nippon yesoensis) in Hokkaido Island, Japan, using hunting records from 1873 to 1882, and assuming 15% and 35% population increase rates. The annual number of deer harvested during 1873 to 1882 ranged from 15,000 to 129,000. The minimum population size in 1873 was estimated as 349,000–473,000. This method was validated by applying it to the eastern population of Hokkaido Island in 1993 when the population size was approximately 260,000, and population sizes estimated by this method were 0.50–1.17 times the nominal population size. Thus, the population estimates from this method were approximately equal to or less than the expected population sizes, and this method can be used to obtain minimum estimates of wildlife populations. Because shorter durations of hunting records result in population size underestimates, it would be better to use hunting record of 10 years or longer in this method. In addition, the degree of underestimation may change with hunting pressure intensity on the populations, other causes of mortality, and maximum annual increase rates of the species. The method can be applied to any wildlife species for which records of annual harvest and maximum annual population increase rates of the species are available. The estimates obtained can provide benchmarks for the population size required for ecosystem conservation, and can be useful for wildlife management as they indicate the lowest limit to maintain the population

Minimum Area Required for Local Populations of Japanese Macaques Estimated from the Relationship Between Habitat Area and Population Extinction

I estimated the minimum area required (MAR) for local populations of Japanese macaques (Macaca fuscata) from empirical data on habitat area and population viability. I used logistic regression analysis to examine the relationship between habitat area and survival/extinction among 50 populations over 50 yr. Estimated habitat areas satisfying 95–99% probability of a population persisting for 100–1000 yr range from 525 to 975 km2. However, confidence limits of parameters in the logistic regression equation are very large. Moreover, the number of extinct population might be underestimated in the empirical data. Consequently, a much wider habitat area (>1000 km2) should be considered for actual conservation planning for local populations of Japanese macaques. The method involves fewer variables and assumptions than previous methods of MAR estimation, and therefore may be a more useful way to estimate MAR for various species and regions

画一的土地利用が生態系機能を失わせ野生動物による農業被害を発生させた

Mass production is a logical outcome of price competition in a capitalist economy. It has resulted in the need for large-scale logging and planting of commercial crops. However, such monotonous land use, or monoculture, has damaged various ecological functions of forests and eroded the beneficial public service provided by forests. In Japan, the most widespread monotonous land use is associated with coniferous plantations, the expansion of which was encouraged by Forest Agency policies from 1958 that were aimed at increasing wood production. By 1986, half of all forested lands had been transformed into single-species conifer plantations. These policies may damage the ecological functions of forests: to provide stable habitats for forest wildlife. In particular, food supplies for wildlife have fluctuated greatly after several decades of logging. Some species have therefore changed their ecology and begun to explore novel environments proactively in order to adapt to such extreme fluctuations. Such species have started to use farmlands that neighbor the plantations. In this sense, crop raiding by wildlife can be regarded as a negative result of monotonous land use due to the loss of ecological functions. Therefore, habitat management to rehabilitate ecological functions and to reorganize the landscape will be required in order to resolve the problem of crop raiding by wildlife. This study examines crop raiding by Japanese deer (Cervus nippon) and monkeys (Macaca fuscata) on the island of Yakushima, which typifies crop-raiding situations in Japan.From the issue entitled "Special Feature on Sustainability and Biodiversity of Forest Ecosystems: An Interdisciplinary Approach

Effects of time and environmental conditions on the quality of DNA extracted from fecal samples for genotyping of wild deer in a warm temperate broad-leaved forest

Extraction of DNA from non-invasive samples (feces) has been used increasingly in genetic research on wildlife. For effective and reliable genetic analyses, knowledge about which samples should be selected in the field is essential. For this reason, we examined the process of DNA degradation in feces of deer. We collected fresh fecal pellets from three wild deer living in a warm temperate forest. We then assessed the effects of time (3, 5, and 10 days) under three environmental conditions (on the forest floor, on exposed ground, and inside the laboratory) on the rates of correct genotyping (CG), amplification failure (NA), genotyping error among positive amplification (ER), false alleles (FA), and allelic dropout (AD) of 15 microsatellite loci. The rate of CG significantly decreased, and those of NA and FA increased with increasing lapse of time. Rates of CG tended to be highest and those of NA, ER, FA, and AD to be lowest in feces kept inside, followed by those on the forest floor. Suitability of samples for DNA extraction was lowest in fecal pellets left on exposed ground, and we suspect that rain may hasten DNA degradation. NA rate could serve as a reliable indicator of the quality of fecal pellets because it was significantly positively correlated with ER rate. For efficient genetic analyses using deer feces in warm temperate zones, we recommend collecting fecal pellets within 3 days of defecation, during periods without rainfall and from under the cover of trees

Autumn Long-distance Movements of Male Japanese Sika deer Cervus nippon yesoensis in Western Hokkaido, Japan

We examined the ranging behaviors of three male Japanese sika deer Cervus nippon yesoensis in western Hokkaido (42°N, 141°E), Japan, from 2003 to 2009. All three deer exhibited similar patterns of long-distance movements in the autumn. They left residence areas between 17 September and 16 October during the rutting season. Their direction of movement appeared to be eastward, and total movement distances ranged from 7 to 26 km. The males tended to return to their residence areas between 10 November and 27 January

Food habits of Japanese deer in an evergreen forest : Litter-feeding deer

We observed the feeding behaviors of wild Japanese sika deer (Cervus nippon yakushimae) in a warm temperate broad-leaved evergreen forest of the island of Yakushima using the focal animal sampling method from April 2002 to June 2006. Sika deer fed on species of at least 73 woody plants, 13 vines, 8 herbaceous plants, 8 ferns, 1 moss, and 3 fungi. We investigated time spent feeding on each food category in each season (spring: April-June; summer: July-September; autumn: October-December; winter: January-March). During each season, 45.6-59.8% of the deer diet consisted of fallen woody leaves. Half of the fallen leaves were those tinged with red and yellow colors. Fallen reproductive parts of plants constituted 8.7-23.7% of the seasonal deer diet. In contrast, living woody parts of plants and herbaceous plants, including ferns and moss, constituted 4.4-22.5% and 0.8-9.2% of the seasonal diet, respectively. Deer also fed on animal matters as minor food items, such as the feces of monkeys and raccoon dogs, bones of deer and monkeys, and bird carcasses. Animal matters constituted 0.3-1.6% of the seasonal diet. Sympatric monkeys supplied food to deer as a result of their daily activities. Monkey-supplied foods comprised 1.7-10.9% of the seasonal diet of sika deer. Monkeys tended to supply many fruits and seeds. Overall, 75.0% of the annual deer diet consisted of forest litter, even though deer had access to abundant living edible leaves in the study area. Therefore, sika deer in this forest ecosystem function ecologically as decomposers rather than primary consumers

Seasonal change in the diet composition of the Asian parti-coloured bat Vespertilio sinensis

We determined the food habit of the Asian parti-coloured bat Vespertilio sinensis from May to August by analysing their faecal samples. Eight orders of insects were identified in the faeces. Lepidoptera, Diptera and Coleoptera had high frequencies of occurrence, but the proportion of each order varied with the sampling period. A comparison between diet composition and relative insect abundance showed that proportions of Coleoptera in the diet were larger than those in insect abundance. This pattern also was true for Lepidoptera in some sampling periods. In contrast, proportions of Diptera in the diet were lower than those in insect abundance, although Diptera was a major prey item. These results suggest that the diet composition of V. sinensis may be biased towards larger-sized taxa. Furthermore, the lack of any significant differences between diet composition and insect abundance for the other five orders suggested that the diet composition of V. sinensis is also influenced by the seasonal prevalence of each insect taxon