Differences in the capture rate of cage‐trapped red foxesVulpes vulpesand an evaluation of rabies control measures in Britain

Abstract

Summary1. Methods used to control canids may differ in their relative effectiveness and how they 'sample' age and sex classes. However, there is little information on such biases. We utilized data from a population of known size and structure to quantify differences in the seasonal capture rate of foxes Vulpes vulpes of different age, sex and social status. The effects of home-range utilization and trap experience were also investigated. 2. The capture rate of juvenile ( < 1 years) foxes was highest in spring and declined throughout the year. Adult ( ≥ 1 years) trap rates were equivalent to those of juveniles in winter. 3. Neither juveniles nor adults exhibited sex differences in trappability. 4. Adults were classified as dominant or subordinate based upon patterns of dyadic interaction. Subordinate foxes were trapped more frequently than dominants. 5. Trappability did not differ inside or outside of core areas, after controlling for trap effort. 6. Previous trap experience did not affect the capture rate of adult foxes. 7. Captures of non-resident foxes peaked in winter (52% of captures), associated with dispersing juveniles and adult males, and were lowest in summer (13%). 8. In Britain, 75-90% of foxes would need to consume poison or vaccine baits to control a rabies epizooty. During simulated rabies control operations, where cage-trapping was used to measure the proportion of foxes taking dummy baits containing a biomarker, < 30% of foxes consumed baits. However, non-resident foxes present during the period of baiting but not during trapping, or vice versa, may bias these calculations. We used the frequency of capture of non-resident foxes to re-examine the success rate of these trials. 9. Revised estimates still suggest that < 45% of foxes were reached during the simulated control operations. This is significantly below the levels necessary for rabies control. Further biomarker trials are required that do not rely only on trapping for sample collection and where the residency status of captured foxes has been determined.

Environmental variation at the onset of independent foraging affects full-grown body mass in the red fox

“…Foxes were captured by netting from den sites or in baited box traps placed in residential gardens (Baker et al 2001a). All individuals were sexed, weighed, aged from tooth wear (Harris 1978) and ear tagged (Rototags, Dalton Supplies Ltd, Nettlebed, Henley-on-Thames, Oxfordshire, UK).…”

Modeling Control of Rabies Outbreaks in Red Fox Populations to Evaluate Culling, Vaccination, and Vaccination Combined With Fertility Control

“…In rural areas the proportion of the population that take baits is likely to be around 70-80% (Masson et al, 1999), whereas only about 40% bait uptake is reported in urban areas of the UK (Trewhella et al, 1991;Baker et al, 2001). Therefore we simulated a range of vaccination rates to study the effects of bait uptake on rabies control.…”

Seasonal and Sex-Specific Differences in Feeding Site Attendance by Red Foxes Vulpes vulpes

“…Sites that provide super-abundant food may also attract foxes from neighbouring territories or further away (e.g. Tsukada 1997) and movements between neighbouring territories can occur yearround (Baker et al 2001). Despite all the relevant variables, information is lacking about seasonal variation in feeding site attendance by both resident and trespassing foxes of each sex.…”

“…For example, attendance may be highest during spring/summer when parents or other group members are food provisioning cubs (Soulsbury et al 2008). In contrast, infrequent attenders at feeding sites would be expected most often during autumn and winter, coincident with dispersal and reproductive movements (Baker et al 2001;Soulsbury et al 2011). Alternatively, feeding sites could be used year-round, representing a stable source of food.…”