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Keywords:

  • badger;
  • fox;
  • monitoring;
  • sign surveys

ABSTRACT

1. A national monitoring scheme for recording the abundance of foxes and badgers in Britain would have to utilize a technique or techniques that could detect a wide range of animal densities in structurally different habitats. Furthermore, the likely reliance on volunteers for data collection means that these techniques must be easily applied by people with different levles of field expertise.

2. Direct methods that rely on counts of the animals themselves (e.g. capture-mark-recapture, radio-tracking, spotlight counts) are generally unsuitable because of cost, manpower and licensing requirements, are not readily applied to all habitats and cannot easily be used by volunteers. However, density estimates derived from capture-mark-recapture and radio-tracking methods are likely to represent the benchmark against which other estimates of abundance are measured.

3. The number of foxes killed per unit area is currently collated by non-governmental organisations for some patterns of land use, e.g. game estates. No such data are available for badgers, as this species is legally protected in Britain. However, the applicability of hunting statistics for monitoring fox abundance is limited by differences in culling effort, the non-independence of different culling practices applied in the same region, possible future changes in the legal status of different culling methods and changes in the ratio of land where foxes are and are not culled.

4. Indirect methods that rely on counts of the signs of the animals (e.g. droppings, breeding refugia) are less expensive than direct methods, can be applied to the range of habitats found in Britain and can easily be used by volunteers. To date, indirect methods have been utilised to derive estimates of relative animal density or the density of social groups. However, the major factor currently limiting the use of indirect methods is that their relationship with absolute animal density has not been validated. The preliminary results of two projects quantifying the use of field signs as a measure of absolute fox and badger abundance suggest that indirect methods could be applicable for monitoring changes in fox and badger numbers at a national scale.