Red Fox Removal and Roe Deer Fawn Survival—a 14-Year Study

Abstract

We studied the impact of red fox (Vulpes vulpes) predation on free‐ranging roe deer (Capreolus capreolus) neonates during 14 years in a mixed forest/agricultural landscape in south central Sweden. A large‐scale natural predator removal experiment occurred when an outbreak of sarcoptic mange (Sarcoptes scabiei) reduced the red fox population initially and caused subsequent variations in red fox abundance. We estimated relative red fox abundance by dividing number of fox observations with number of person‐days in field. Red fox predation accounted for 88% of known mortality in roe deer fawns. Predation was closely correlated to red fox abundance, and there was a strong negative correlation between fox abundance and overall fawn survival. Fox abundance was the only factor with a significant effect on between year variation in fawn survival. Annual predation varied between zero and 90%. Our study recorded the highest predation rates for roe deer juveniles established to date. High fawn survival in years of low fox abundance suggested that predation mortality was additive during summer. Our results supported the conclusion that the large national increase of roe deer in Sweden during the 1980s and 1990s was related to lower fox predation on fawns and also indicated that the roe deer population density was well below habitat carrying capacity at the onset of the mange epidemic. In Sweden, in general, a thorough fox control will most likely result in increased fawn survival and higher potential roe deer harvest.

Long-term data on invaders: when the fox is away, the mink will play

“…Red fox has been hunted continuously throughout the study period, because they prey on domestic animals and compete with hunters for small game species. Jarnemo and Liberg (2005) further showed that the number of fox observed agreed well with the number of fox shot during a 14-year study period. Likewise, the American mink, which preys heavily on fish, crayfish, and ground-nesting birds, rapidly became a nuisance species in Sweden, making it a prime target in hunting, and wildlife management.…”

“…Critical comparisons with other abundance estimates, such as count data, have either yielded very similar results (Cattadori et al 2003;Jarnemo and Liberg 2005) or have shown that the spatio-temporal patterns of the population dynamics may differ if based on harvest data as compared to count data (Ranta et al 2008). Species-specific changes in the hunters' harvest effort may also bias harvest data (Winterhalder 1980).…”

“…Introduced mammals such as feral cats (Felis catus) or rats (Rattus spp.) might be the most important cause of vertebrate extinctions during the last half-century, particularly on islands (Groombridge 1992;MacPhee and Flemming 1999). Other than that, we know little about the long-term effects of invasive mammals .…”

Maternal and individual effects in selection of bed sites and their consequences for fawn survival at different spatial scales

“…Due to the minimal odor presented by fawns (Jackson et al 1972), predators mostly rely on vision when hunting fawns. The visual hunting strategy used by red fox (Vulpes vulpes)-shown to be the major predator of roe deer fawns in Sweden (Jarnemo 2004;Jarnemo and Liberg 2005)-is not likely to be efficient in the dense beech and oak forests of our study site. In addition, the density of foxes at Trois Fontaines is relatively low (D. Delorme, personal observation).…”

Low-cost infrared sensor for wildlife detection in vegetation

“…It is caused by roe deer fawn natural instinct to stay lay low and still in the vegetation, which increases their risk of being killed or injured by agricultural machinery (Kittler 1979). Although a great importance of mortality caused by harvesting devices had been highlighted by several authors since the 1970's, it started to receive more attention in the past decade (Gaillard et al 1998;Jarnemo 2004;Jarnemo, Liberg 2005). Death of fawns from agricultural machines is severe in most cases, with frequent cases of cut feet and subsequent bleeding.…”