Governments Inert, as Dogs Continue to Mix with Europe’s Wild Wolves

Dogs are interbreeding with wolves in the wild, posing a threat to wolves’ ecological role, their unique looks, and the cultural and aesthetic values associated with them. A new study finds that wolf-dog hybridisation has been documented in all European wolf populations, and highlights that most European governments are failing to intervene to monitor and address this issue.

Wolves are a protected species. Dogs are a domestic animal. Today, both wolves and dogs roam Earth. However, many tens of thousands of years ago, dogs didn’t exist. Dogs have descended from wolves through artificial selection and domestication by humans, acquiring new shapes, behaviours and values to society in the process. Meanwhile, wolves retained their key ecological function as apex predators and their symbolism to people.

In the last ~30,000 years during which both wolves and dogs have been present, the two have occasionally interbred. However, compared to the past, today the number of free-ranging dogs in the wild is in the millions, and landscapes are significantly more fragmented and laden with human activities. This suggests that the occurrence rate of wolf-dog hybridisation is greater today than it was in the past, which is what has been worrying scientists especially in the recent decades. Greater occurrence of hybridisation risks compromising the conservation of wolf populations in terms of their genetic identity and integrity, their ecological functions, and their cultural and aesthetic values.

The wolf-dog hybridisation issue is receiving particular attention in Europe, where international laws and legal agreements for nature conservation (i.e., the Bern Convention, and the EU Habitats Directive) require its prevention and mitigation, including through measures such as reducing the number of free-ranging dogs and removing the hybrids from the wild.

A new study published in Biological Conservation co-authored by experts of the IUCN’s large carnivore specialist group (, made a first assessment of this issue in Europe and addressed the extent to which European governments are implementing the indications of international legislation.

The study finds that hybrids have been detected in all European wolf populations and are found in 21 out of 28 countries today.  Moreover, crucially most countries are found to be failing to implement any active management of the hybridisation issue, including zero monitoring, which is alarming as hybridisation rates could be rising but remaining undetected.

In a recent (unpublished) press release, the lead author of the study Dr Valeria Salvatori based at the Institute of Applied Ecology in Rome, urged governments to intervene: “we are still in a position to tackle this issue effectively if prompt action is taken at the continental scale”, she said.

The first step towards such coordinated continental action is to agree on a common definition of what a hybrid is. Hybrids can backcross with wolves indefinitely, and at any given time there may be hybrids of different generations bearing greater or smaller percentages of dog genes, in the wild. A main issue lays in deciding what is an acceptable proportion of wolf/dog genes in an individual for it to be considered a wolf, and what tools should be used for the genetic analyses, as several types are available that would each give different results.

The second step is to grant the hybrids a protected status from a legal point of view, to avoid loopholes whereby the illegal killing of wolves could be defended in court as a hybrid misidentification. For this reason, hybrid management should be in the hands of government agencies.

The authors conclude the paper proposing three aspects that current international laws need to incorporate in their texts to the aid effective mitigation of the wolf-dog hybridisation issue. These include an accurate definition of “hybrid” to be standardised across the continent, a guidance document on how hybrids should be managed (e.g., lethal/non-lethal removal), and a clear set of provisions to mitigate the presence of free-ranging dogs and minimise their interactions with wolves.

“Only by expanding on the currently available guidance in the manner indicated above can the two main international legal instruments for European nature conservation effectively contribute to the management of [wolf-dog hybridisation] at the continental scale”, the authors conclude the paper.

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Salvatori, V., Donfrancesco, V., Trouwborst, A. et al. 2020. European agreements for nature conservation need to explicitly address wolf-dog hybridisation. Biological Conservation248, p.108525.

Cover image credits: Jannik Selz on Unsplash

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