Doncaster (1992) hedgehog intraguild badger predation regulating effects
Title: Testing the role of intraguild predation in regulating hedgehog populations, Proceedings: Biological Sciences 246 (1324); 113-117. 1992
Authors: C. P. Doncaster
Background to study
An investigation into the factors responsible for small-scale discontinuities in the distribution of hedgehogs using an experimental perturbation approach.
- Hedgehogs were fitted with radio-transmitters, released into two sites of similar habitat including woodlands, urban, roads and pasture. 20 individuals were released into a control site known to support hedgehogs at a density of 25/sqKm and 30 were released into Wytham woods where hedgehogs were known to be absent. Resident individuals from the control site were removed prior to the release.
- The movements of released individuals were monitored for 2 months by obtaining location fixes during nightly patrols and individuals encountered were re-weighed.
- Known fate of individuals, dispersal movements and habitat preferences were recorded and compared between the two sites.
- Survival of hedgehogs was significantly lower at Wytham woods than at the control site. Road traffic accounted for deaths at both sites but the main difference in mortality was due to badgers which accounted for seven deaths at Wytham compared with no deaths at the control site.
- Hedgehogs released into Wytham Woods dispersed twice as far from the release point than those released into the control and females at Wytham dispersed at least as far as males (mean distance of females 2.1 km and1.8 km for males).
- After 20 days individual movements stabilised and mortality declined at Wytham in the second month when the majority of hedgehogs had dispersed from the site (3 of 30 remained).
- 14 of the 18 surviving hedghogs released in the Wytham settled in gardens of the six nearest urban areas, five of which already sustained hedgehog populations.
- Roads did not present a barrier to movement with a major trunk road being traversed by 22 hedgehogs and a 12 m wide section of the River Thames was crossed by one female.
- Grass pasture and gardens were occupied in preference to other habitats at Wytham whilst woodland, which contained the highest concentration of badgers, were not favoured.
- Arable land was avoided at both sites.
- Males released into Wytham gained mass faster than those released at the control site and may reflect differences in foraging observed between the two sites, where 55% of pooled fixes at Wytham were in residential gardens, compared with only 20% at the control.
Key messages to landowners and managers derived from these results
- Badgers are a major factor contributing to distribution of hedgehogs within rural landscapes, resulting in hedgehogs being lost from areas where badgers are at high density. Creating refuge habitat within rural settlements is recommended to provide refuge for hedgehogs and prevent populations becoming fragmented.
- Releases of rehabilitated hedgehogs should be carried out in areas where badgers are either absent or at low density to increase the chances of survival and settlement.