Field test for environmental correlates of dispersal in hedgehogs Erinaceus europaeus
Patrick Doncaster C., Rondinini C., Johnson PCD.
1. We report a field experiment designed to explore the responses by hedgehogs to novel and unfavourable terrain, which they encounter when dispersing between fragmented local populations in farmland. We identified four replicate sites as unused by hedgehogs, but lying between existing populations and containing locally abundant food. At each site, we released six hedgehogs from distant sources at 2-day intervals and monitored their subsequent dispersals over 20 days by radio-tracking. We compared movement trajectories under this treatment to those of 29 hedgehogs released at two sites known to support abundant hedgehogs. A third treatment comprised 20 unmanipulated hedgehogs at three sites. We estimated habitat use and proximity to habitats by comparing each observed trajectory to simulated random walks of equal length. We sought differences between treatments in movement and habitat use from nested analysis of variance. 2. No two trajectories of any translocated hedgehogs followed the same route; most involved little change in body weight, and took the animal into or through existing populations. Hedgehogs moved substantially further and faster on average from the unfavourable than from the favourable sites. They showed a significantly stronger attraction to habitat edges, which therefore acted as corridors, and a significant proportion of them stayed closer to roads and to urban habitat than random expectation. Habitat preferences also shifted significantly towards urban and away from arable areas. Six were predated, and two killed by road traffic. At least three returned to their release point, with P < 0·05 of this occurring by chance. 3. In this region, natural dispersals between populations up to 4 km apart are rare events. We have shown, however, that hedgehogs are capable of travelling distances of up to 3·8 km from a release point, and up to 9·9 km in total, compared to an average home range span of 0·8 km, and it appears that none of the local populations in the study area are out of reach of neighbours.