Pesticides and Hedgehogs: A Toxic Coexistence Revealed by Science

Long a discreet mascot of European gardens, the European hedgehog (Erinaceus europaeus) is now at the center of an alarming environmental warning. A Danish study recently published in *Frontiers in Veterinary Science* sheds light on the widespread contamination of these small mammals by a multitude of pesticides. This is yet another warning sign for a species already classified as vulnerable in many European countries.  

Pesticides Are Ubiquitous in Hedgehogs’ Bodies

Conducted in Denmark, this study relied on the toxicological analysis of 115 liver samples from hedgehogs that died in 2016. The goal? To test for the presence of 19 chemical substances, including rodenticides, insecticides, and herbicides. The results are telling: 84% of the samples contained at least one rodenticide, 50% contained a herbicide, and 43% contained an insecticide. Even more concerning, nearly 80% of the hedgehogs had multiple residues, with some containing up to nine different pesticides. Among the most frequently detected substances are:

• bromadiolone, an anticoagulant pesticide that is lethal to rodents (in 79% of cases);
• imidacloprid, a neonicotinoid widely criticized for its effects on pollinators (in 35% of cases);
• metamitron, a herbicide (in 29% of cases).

While these figures do not yet allow for a precise assessment of lethal or sublethal risks to hedgehogs, chronic exposure has been confirmed.  

Revealing Geographical Differences

The study also highlights significant regional disparities between eastern and western Denmark, likely reflecting differing agricultural practices. This geospatial dimension, rarely explored in wildlife studies, underscores the importance of refined regional monitoring.  

A Threat Identified in France

The phenomenon is not limited to Denmark. In France, the Center for Nature and Environmental Education and Research (CHENE) has been conducting a large-scale investigation into the causes of hedgehog mortality since 2019. Its analyses reveal an alarming mortality rate among juveniles, often linked to chronic diseases, road traffic, and exposure to agricultural chemicals. Other studies report that nearly 80% of hedgehogs in France have disappeared over the past two decades. Among the main culprits: pesticides and rodenticide baits, as well as mechanical traps, which are still overused in gardens.  

An Environmental Sentinel in Danger

Considered a good bioindicator, the hedgehog serves as a sentinel for urban and rural biodiversity. Its diet (worms, slugs, insects) and behavior make it particularly vulnerable to the bioaccumulation of contaminants. As the Danish study notes, there is currently no specific toxicological threshold for this species, which complicates the assessment of long-term effects.  

A Need for Regulatory Vigilance

As the European Union debates the reauthorization of certain controversial pesticides, these findings add weight to calls for stricter usage restrictions, including for products sold to consumers. According to scientists, systematic, multi-species monitoring is essential to better understand the cumulative effects of chemicals on wildlife. The contamination of ecosystems does not affect only pollinators or rivers. The hedgehog, though so familiar to us, has unwittingly become a silent witness to the widespread poisoning of living organisms. It is time to listen to it…