Assessment of a daily defecation rate of fallow deer upon a closed population study

KOSNAŘ, A. , RAJNYSOVA, R. : Assessment of a daily defecation rate of fallow deer upon a closed population study. Acta univ. agric. et silvic. Mendel. Brun. , 2012, LX, No. 6, pp. 173–180 Many indirect methods of counting even-toed ungulates are based on the principle of accumulating dung in a known area per a unit of time. In order to provide the most accurate assessment of the population size, these methods require the knowledge of daily defecation of the monitored species. The main objective of the study submitted is the assessment of a daily defecation rate of fallow deer based on the monitoring of its closed population. A partial objective is the assessment of the distribution of fallow deer in an enclosed area with a view to biotopes represented. A fallow deer population was studied for the period of three years (2009–2011) in a fenced-in area (8 ha). During this period, dung heaps were counted in forty sites with the total area of 0.8 ha in all seasons of the year. In each season, the sites were cleared, and the dung was counted a er a seven-day exposure. This counting was performed twice in each season. Thanks to the precise knowledge of the number of monitored animals, daily defecation rates (DDR) were derived upon the dung found, using a formula for the calculation of population density. Subsequently, the determined DDRs were verifi ed by direct observation. The highest average DDR value calculated from the formula (21.11 ± 0.32 S.E.) was obtained in the summer season. The lowest defecation of fallow deer was established to be in winter (12.34 ± 0.25 S.E.) and early spring (10.61 ± 0.24 S.E.). Dama dama, defecation rate, fallow deer, pellet groups Fallow deer belong to the most common species of cloven-hoofed animals in Central Europe (Chapman & Chapman, 1980). Overabundant, this species o en causes damages to crops and forest vegetation (Kay, 1993; Mouissie et al., 2005; Gill & Beardall, 2001). Similarly as with other even-toed ungulates, for game management to be performed properly it is necessary to know the population density in the area concerned. For this purpose, numerous counting methods may be used (Putman et al., 2011), many of which are based on accumulating dung in a known area per a unit of time. These indirect counting methods have been successfully used in wooded areas with lower visibility (Aulak & BabinskaWerka, 1990; Acevedo et al., 2008); they may also be utilised in extensive areas with lower human population density and minimum number of fi eld workers (Forsyth et al., 2007). The methods gain a higher accuracy with higher population densities of the species monitored (Neff , 1968). Two factors are recognised as the main sources of potential errors in these methods – dung decomposition time and the daily defecation rate (DDR) specifi ed in the number of dung heaps per animal and day (Cederlund et al., 1998; Ronnegard et al., 2008). Errors caused by the pellet disappearance factor may be minimised by a suitable setting of the counting periods (Massei et al., 1998; Tsaparis et al., 2008). In the winter season, decomposition processes are slowed down, and signifi cantly longer periods of time may be selected (Cambell et al., 2004; Therekauf et al., 2008). What is considered more problematic is the use of the correct DDR value. The reason for this is the DDR variation in the time and area of counting, caused especially by the change of food and climatic conditions within the year, activity 174 A. Kosnař, R. Rajnysova of the species, and type of habitat (Mitchell et al., 1985; Rogers, 1987; Prokesova et al., 2006). Further important factors aff ecting the daily defecation rate are the age structure of the herd and proportion of sexes in the population monitored. Studies dealing with the fallow deer DDR have been conducted in Western Europe and the Mediterranean (Bailey & Putman, 1981; Massei & Genov, 1998). Hitherto ascertained values for the fallow deer DDR range between 11.3 and 26.5, but many studies give only winter DDR values (Stubbe & Goretzki, 1991). The objective of this contribution is to assess the fallow deer DDR in various seasons of the year for Central European conditions, and to compare results obtained with available literature. MATERIAL AND METHODS