Changes in the density and spatial distribution of red fox dens and ...

Response of red fox to rabies vaccination 125Table 2. Mean annual cull of red foxes in the study area and its vicinity (2001–2005).Monitoring districtArea (ha)Mean annual culln n/km 2Brzeziny 6000 11.8 0.20Regny 9000 34.4 0.38Cietrzew 8300 30.4 0.36Study area 8900 64.2 0.72in 2004–2005, 24% of all breeding dens wereoutside forest (Misiorowska 2005). In Poland atthe turn of the 1970s, the percentage of foxbreeding dens located outside forest was low,even in territories with limited forest cover(Pielowski 1976, Goszczyñski 1985, Go³dyn et al.2003). However, by the end of the 1990s, in theCzempiñ area, (where the level of afforestationdoes not exceed 6%), almost 83% of breedingsites were located outside the forest (Panek andBresiñski 2002). In another study, a high densityof foxes (2.2 ind./km 2 ) and a large number ofnatal dens were reported from a farmland areain Wielkopolska (Go³dyn et al. 2003). The increaseduse of breeding dens located in anagricultural landscape may indicate profoundchanges of habitat use by foxes, and adaptationto a human-modified environment (Bresiñskiand Panek 2000, Tryjanowski 2000, Panek andBresiñski 2002).During the last five years the average foxnumbers at the beginning of the hunting seasonwas approx. 80 ind. This number was estimatedon the basis of annual number of natal dens (15),mean number of cubs per den (3.4), and thenumber of adult foxes per occupied den (2). Thisvalue slightly exceeded an average annual huntingbag in the same period (approx. 64 per year).It could be expected that such a high huntingpressure resulted in a decrease in fox numbersand density in the following year. However, inevery subsequent winter, fox density remainedstable or even increased: from 12.7 tracks/km/24hrs to 13.49 in the 2000/2001 and 2004/2005hunting seasons respectively. Similarly, in everysubsequent spring, the number of occupied familydens showed an increasing trend (Misiorowska2005). This suggests that intruders fromneighborhood nearby formed an important partof the local population in our study area inautumn-winter. Probably, during the autumnand winter, young foxes dispersed from adjoiningterrains, where hunting pressure waslower (Table 2).Similar observations of compensation forpopulation wastage due to intensive shootingwere described by Reynolds et al. (1993), Côtéand Sutherland (1997) and Vos (2003). Intruderslead a nomadic life, and use forests as naturalshelter during the day. As a rule, these foxescirculate around and inside occupied territories,not using existing, occupied dens as temporaryrefuges. In effect, some of these animals stayabove ground during the day. The results withthe battue (driving) method applied in forestconfirm this suggestion: the greatest increase infox numbers, of more than 100%, was found forthis. The battue method is the best of the threeused to assess numbers of nomadic animals. Incases of high fox mortality (eg with intensiveshooting), some nomadic animals eventually occupyvacated territories and stabilize the wholepopulation (Jasja et al. 2001, Vos 2003).Our results may also have practical implicationsfor hunting management. An increased foxpopuation is regarded as the main reason for thedecrease in small game populations (Panek et al.2006). However, the successful reduction of thefox population over areas covering only severaldozen square kilometres, as in case of our studyarea, is not possible, if shooting pressure on adjoiningareas is low. From a game managementpoint of view, the goal should therefore lie in anintensive and coordinated increase in fox culling