Mortality, diseases and diet of European hedgehogs (Erinaceus europaeus) in an urban environment in Finland

Abstract

Western European hedgehogs (Erinaceus europaeus) are commonly found in urban environments. To evaluate human-hedgehog interactions on the northern margin of the hedgehog range, we investigated the causes of mortality, the occurrence of diseases, parasites and bacterial infections, and the diet of hedgehogs (males n = 87, females n = 66, sex unknown n = 100) found dead in Joensuu, Finland, during the years 2004–2005. Hedgehog carcasses were obtained from a radio telemetry tracking study and a traffic mortality survey conducted by us, as well as from local people who provided us with dead hedgehogs. Of the carcasses obtained during the tracking study, 75 % died of human-related causes. The vast majority (97 %) of human-related deaths were road kills, and more than half (56 %) of natural deaths were by starvation. The average number of hedgehogs killed on the roads was 0.65 per 100 km of road transect studied. Purulent and gangrenous inflammation of the limbs was found in 11 adult males (out of 38 collected) in pathological examinations. The Salmonella enteritidis (phage type 20) infections that were found in 57 % of the individuals examined were typically latent and were mainly found in the liver. Lungworms (Crenosoma striatum) were found in 79 % of the individuals examined. Altogether, 92 % of the stomachs contained remains of human foods, especially fish and milk. The hedgehogs’ natural diet included invertebrates such as beetles (Coleoptera) and earthworms (Clitellata). Our results show that the main negative anthropogenic impact on hedgehogs is severe traffic mortality. The observed high prevalence of Salmonella calls for appropriate hygienic measures when feeding and handling hedgehogs.