The fate of rescued hedgehogs (Erinaceus europaeus) released back to the wild has now been the subject of several follow-up studies. Although subject to various hazards, released hedgehogs have clearly shown essential ‘life-skills’. However, all previous studies have involved releases into hedgehog-rich areas and the observed long-range (> 500m) dispersal movements shown by some subjects, of up to 5km, may be a consequence of local intraspecific competition. This study has reduced a number of potentially confounding subject variables and provides follow-up data on 12 age-matched female hedgehogs with similar histories. A main group (n = 10) was released into a rural woodland area (Surrey, UK) of low natural hedgehog density, and radio-tracked for up to 108 days. A pilot release of two animals in an urban area with an established hedgehog population also took place (tracked for 109 and 131 days respectively). Most of the main group dispersed (up to 3km) from the release site; the two animals in the urban site did not. These data, taken with those from previous studies, suggest that dispersal is not specifically the result of intraspecific competition. Overall survival at week 8 was 42per cent (5 hedgehogs) plus two lost animals. This is comparable with previous studies. However, survival fell to 25 per cent (3 animals) plus two lost animals by week 15. Of seven recorded deaths, only one was the result of a failure to thrive and all other mortalities were accidental: four road deaths, one drowned in a pond and one predation. The study concludes that the hazards of the human environment were the principal threat to the welfare and survival of released hedgehogs in the area.

Although there is an increasing understanding of the role of parasites in their host dynamics, accurate, quantitative estimates of parasite caused morbidity in wild animals are rare. Here, we examine the possible impact of 2 tick species (Ixodes ricinus, I. hexagonus) on the condition of the European hedgehog (Erinaceus europaeus). For this, we tested for correlations between blood parameters of 36 adult hedgehogs from an experimental population enclosed in a natural habitat and their tick infestation over a period of 8 months (March–October 2007). We found correlations between the tick infestation and the concentration of red blood cells, haemoglobin, haematocrit, MCH, MCHC, thrombocytes, lymphocytes and neutrophils. These results indicate that ticks can induce anaemia in the hedgehog. The peripheral blood characteristics and the erythrocyte indices characterize this anaemia as haemorrhagic and regenerative. During the course of our study the hedgehogs of our population showed below normal mortality but morbidity was found to be high resulting from the blood loss caused by the feeding activity of the ticks.