Wildlife management systems face growing challenges to cope with increasingly complex interactions between wildlife populations, the environment and human activities. In this position statement, we address the most important issues characterising current ungulate conservation and management in Europe. We present some key points arising from ecological research that may be critical for a reassessment of ungulate management in the future.
Although drive counts are frequently used to estimate the size of deer populations in forests, little is known about how counting methods or the density and social organization of the deer species concerned influence the accuracy of the estimates obtained, and hence their suitability for informing management decisions. As these issues cannot readily be examined for real populations, we conducted a series of ‘virtual experiments’ in a computer simulation model to evaluate the effects of block size, proportion of forest counted, deer density, social aggregation and spatial auto-correlation on the accuracy of drive counts. Simulated populations of red and roe deer were generated on the basis of drive count data obtained from Polish commercial forests. For both deer species, count accuracy increased with increasing density, and decreased as the degree of aggregation, either demographic or spatial, within the population increased. However, the effect of density on accuracy was substantially greater than the effect of aggregation. Although improvements in accuracy could be made by reducing the size of counting blocks for low-density, aggregated populations, these were limited. Increasing the proportion of the forest counted led to greater improvements in accuracy, but the gains were limited compared with the increase in effort required. If it is necessary to estimate the deer population with a high degree of accuracy (e.g. within 10% of the true value), drive counts are likely to be inadequate whatever the deer density. However, if a lower level of accuracy (within 20% or more) is acceptable, our study suggests that at higher deer densities (more than ca. five to seven deer/100 ha) drive counts can provide reliable information on population size.
The wild population of fallow deer in Central Europe has grown considerably over the last decade. However, information on feeding habits of this alien species in relation to the indigenous red deer or roe deer, in areas of their co-occurrence, is scarce. A prevailing view maintains that their food-niches are distinct, although direct comparative studies have not been carried out. Therefore, the aim of the research was to compare the diets of fallow, red, and roe deer feeding in the same habitat. Research was based on the rumen contents of 242 animals hunted in the autumn-winter season in the forests of Southern Poland. The analyses demonstrated that fallow deer are moderate grazers in such conditions and eat more graminoids in comparison to red or roe deer (36.4% vs. 16.1% or 5.5%, respectively). On the other hand, it feeds on less browse (17.2% vs. 41.4%) or dwarf shrubs (8.4% vs. 19.0%) than red deer, and on less bramble (10.9% vs. 34.6%) or forbs (4.0% vs. 7.6%) in comparison to roe deer (P=0.05). Although the diets of the three deer species differ in terms of the proportion of each food type in their diet, overlapping of their food-niches is high (52.6%).
In¯uence of habitat type on the group size of sika deer was analysed on the basis of 2718 individuals observed in 708 groups, in the area where deer are under pressure neither from predators nor hunters. From spring to autumn, the percentage of individuals observed in the largest groups in open woodland was higher than both in clearings and closed woodland. In early winter, the percentage of individuals aggregated in the largest groups was highest in the clearings, while in late winter, the percentage of individuals observed in the largest groups was highest in the closed woodland. Besides, the percentage of large groups observed in the morning and evening (when most of deer are active) was much higher than during daytime (when level of deer activity is lower). Changes in food availability are suggested to be a factor responsible for variation in sika deer group size in different habitats.
The influence of population density of sika deer (Cervus nippon) on their activity, habitat use, and habitatrelated group size was studied in the area of Japan's Tanzawa Mountains in early winter. The percentage of active sika deer was higher in January 1994 (a low-density period) than in January 1995 (a high-density period). The pattern of habitat use differed between periods. During the high-density period, deer increased their relative use of lower quality habitats. A possible mechanism and implications of this are discussed. Changes in population density had a positive effect on group size in sika deer, though the variation among habitat types supported the hypothesis that food biomass is an important determinant of group size.
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