Study confirms low percentage of dog and wolf crossbreeding in Swiss wolf population

The wolf has naturally recolonised the Alps in the last decades. But the wolf’s precense in a densly inhabited and used region, such as Central Europe, arises conflicts. Particularly, livestock owners and hunters oppose the comeback of the wolf. Many wolf opponents keep raising the argument of a high rate of hybridisation as a reason to shoot wolves. However, Swiss scientists came to the result that the dog introgression in the Swiss wolf population is very limited. This result debunks the argument that hybridisation would be a problem in the alpine wolf population.

Roots of hybridisation

Wolf-dog hybrids have been reportet all over Europe. Particularly, hybrids from male dogs and female wolves were subsequently integrated into wolf packs and backcrossed with wolves again. Several studies conducted in the last years took a closer look on the modality of wolf-dog hybridisation in the European wolf populations. Overall, the rate of hybridisation strongly depends on the level of disturbances to the wolf populations. This particularly means the presence and abundance of feral and stray dogs, for example close to anthtopogenic environments. As expected the rate of hybridisation is low in Western Europe, with for example 0 to 6,5% across the Italian Appenines and the Iberian Peninsula. Eastern Europe on the other hand shows higher percentatges, with 10 to 14% in Georgia, Bulgaria and Greece. This can be lead back to the high number of free-ranging dogs.

Unclear legal status of hybrids

The Bern Convention lists the Alpine wolf population as “endagered”. However, hybrids often fall into a legal gap. It is recommended to remove them in order to protect the integrity of wild wolf populations. The majority of the alpine wolves live in the Western parts of the Alpes between France and Italy. Only three packs established in Switzerland even though tens of individuals migrate thtrough the country every year. The rumor of wolf-dog hybrids is widespread in the public and is often used as a reason to minimise the wolf population. Debunking this argument is incredibly important to guarantee an objective discussion about the future wolf management and the wolf’s social preception in Switzerland.

EWS - Wolves WWF -00167_.jpg-© Wild Wonders of Europe /Sergey Gorshkov / WWF
© Wild Wonders of Europe /Sergey Gorshkov / WWF

Swiss scientists debunk rumour of wide-spread hybridisation

Scientists from the University of Lausanne conducted a long-term genetic survey of detected wolves in Switzerland and adjacent regions. The survey is part of an ongoing non-invasive genetic monitoring that started when the first wolves settled in the country, so more than 20 years ago. The scientists genotyped thousands of DNA samples and perfomed admixture analyses of genotypes of putative wolves and reference dogs. The objective was to estimate the hybridisation and admixture rate in the newly colonised Alpine wolf population. In the end the scientists were able to assign 1 645 samples of wolf salvia, faeces, blood, hair and tissue to 115 individuals. The samples of these individuals were collected between 1998 and 2017. The scientists then compared them with reference samples from 70 dogs.

The results of the study show that less than 2% of the animals had DNA that showed sings of hybridisation. The two estimated cross-bread wolves were properly the outcome of a wolf and dog mating at least two generations ago. The three Swiss wolf packs show no signs of cross-breading with dogs. The results of this study are in line with previous similar studies from Italy and Spain. Luca Fumagalli, one of the researchers working on the project, says:

Our results prove that dog-wolf cross-breeding is very limited in reality, even anecdotal, and that the genetic integrity of wild wolf populations livin in the Alps remains intact.

Luca Fumagalli
Researched, University of Lausanne

The Swiss laws recommend the culling of hybrids to preserve the integrity of the pure wild populations. However, Luca Fumagalli implies that controlling the presence of stray dogs that transfer their genes to wolves would be the crucial taks in keeping hybridisation low in the future.

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2 thoughts on “Study confirms low percentage of dog and wolf crossbreeding in Swiss wolf population

  1. Wolves are well-known to travel over hundreds, sometimes even thousands, of kilometres. Wolves in Switzerland arrived from the Apennine population in Italy, a country said to have over a million stray dogs roaming. As the study states in the discussion:
    “Feral and stray dogs are supposedly absent in Switzerland, and wolves usually avoid the immediate vicinity of human settlements. All dogs detected here are doubtlessly pets, hunting or guarding dogs, the Swiss mountains being extensively hiked and exploited for pastoralism. Although local crossbreeding cannot be ruled out, these rare hybridization events may have rather occurred in the Apennines, the source population of Alpine wolves24,25. About a million of free-ranging dogs has been reported over Italy by perhaps outdated estimates (10% of feral individuals38,39). While the overall dog introgression rate of Italian wolves still remains low (<7%, Table 1), some localized areas host introgressed packs21. Among them, western Tuscany, at the northwestern edge of the Apennine population, appears to be a hotspot of wolf × dog hybridization20, near the corridor connecting the Apennines and the Alps. Alpine wolves thus seems to have avoided gene flow with dogs and admixed individuals, which is remarkable given the low numbers of effective founders that arrived in this human-dominated region (~1525).”

    In addition, the data in Table 1 provides more proof that hybridisation rate in many countries is lower than the numbers claimed by people against their presence.

  2. the reason is that Swiss people do not allow for their dogs to wander on their own, so in this country a number of stray dogs is minimal + the number of wolves in Switzerland is so low, that statistical chances for a succesful mating between dogs and wolves there is close to zero

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Sign the Open Letter to the German Ministry

Join more than 70 forest experts demanding a radical change in the German forest management system.

Open Letter to the German Ministry of Food and Agriculture

Federal Ministry of
Food and Agriculture
Minister Julia Klöckner
11055 Berlin

Dear Minister Klöckner,

The current situation of the forest in Germany is worrying. It is a forest crisis not only driven by climate change. The current crisis management of the forestry industry is backward-looking and harmful to the forest. The declaration announced at the meeting of ministers in Moritzburg can be described as a `Moritzburg declaration of bankruptcy´. We call on the state forestry industry to, instead of expensive rushed actions, finally carry out an expert analysis of its own work and to involve all stakeholders in this process. What is called for is a consistent departure from plantation forestry and a radical shift towards a management that treats the forest as an ecosystem and no longer as a wood factory.

On 1stAugust 2019, five forestry ministers of CDU and CSU-led states adopted a so-called “master plan” for the forest in Germany, which was affected by heat, bark beetles, fire and drought. As of 2020, the federal government is to make 800 million euros available as a reaction to climate change. This money is to be used to repair the damage caused, reforest the damaged areas and carry out `climate-adapted´ forest conversion – including the use of non-native tree species that have not yet been cultivated in the forest. Research should therefore focus on on tree species suitability and forest plant breeding in the future – keyword: `Climate-adapted forest of the future 2100´.

Remarkably, the damage caused primarily by the extreme drought of 2018 is attributed solely to climate change. Climate change is meeting a forest that is systemically ill due to the planting of non-native tree species, species poverty, monocultures, uniform structure, average low age, mechanical soil compaction, drainage etc. A healthy, resistant forest would look differently! The master plan emphasizes: sustainable, multifunctional and `active´ forest management remains indispensable – and thereby means that its unnatural state cannot be changed. Reference is made to the `carbon storage and substitution effects´ of wood products. The use of wood, e.g. in the construction industry, should be increased and thus the demand for wood should be further fueled – while knowing that the forest in Germany already cannot meet this demand. In fact, forest owners are suffering from poor timber prices due to an oversupply of trunk wood on the world market.

All these demands make clear: the current forestry strategy, which has been practiced for decades, should not change in principle. The concept is simple: cut down trees – plant trees. At best, the `design´ of the future artificial forests consisting of perfectly calculated tree species mixtures, that are believed to survive climate change without damages, can be changed. In all seriousness, the intention is to continue selling the public a so-called `future strategy´ to save the forest. This strategy seamlessly follows the model of a wood factory, that is met with general rejection and must be regarded as a failure in view of the coniferous plantations that are currently collapsing on a large scale. An essential part of the forests that have currently died is exactly the part that was reestablished in 1947 as coniferous monocultures on a much larger area than today. There is only one difference to the situation at the time: considerable amounts of money are to be made available from taxes for forest owners this time.

Climate change is progressing, and this, without a doubt, has massive impacts on all terrestrial ecosystems, including forests. To pretend that the last two years of drought alone caused the disaster is too cheap. On closer inspection, the disaster is also the result of decades of a forestry focused on conifers – in a country that was once naturally dominated by mixed deciduous forests. People do not like to admit that for more than 200 years they have relied on the wrong species of commercial tree (spruce) and have also created artificial, ecologically highly unstable and thus high-risk forest ecosystems. A whole branch of business has become dependent on coniferous wood. And now the German coniferous timber industry is on the verge of bankruptcy.

It would only have been honest and also a sign of political greatness if you and the forestry ministers in Moritzburg had declared: Yes, our forestry industry has made mistakes in the past, and yes, we are ready for a relentless analysis that takes into account not only purely silvicultural, but also forest-ecological aspects. Instead, you have confined yourselves to pre-stamped excuses that are already familiar to everyone and that lack any self-critical reflection.

Clear is: We finally need resting periods for the forest in Germany, which has been exploited for centuries. We need a new, ecologically oriented concept for future forest – not a hectic `forest conversion´, but simply forest development closer towards nature. This gives the forest as an ecosystem the necessary leeway to self-regulate and react to the emerging environmental changes. We need a systemic forest management that is no less profitable than the present one, but must be substantially more stable and resistant to foreseeable environmental changes. The aid for forest owners that all citizens are now required to pay through their taxes is only politically justified in the interest of common good, if the forests of the future that are being promoted by it, do not end up in the next disaster, some of which is produced by the forest management itself.

That is why the signatories request from the the Federal Government, and in particular you, Mrs Klöckner, a master plan worthy of the name:

On disaster areas (mainly in public forests!) reestablishment through natural forest development (ecological succession), among other things with pioneer tree species, is to be brought about. In private forests, ecological succession for reestablishment must be purposefully promoted. Larger bare areas should be planted with a maximum of 400 to 600 large plants of native species per hectare in order to permit ecological succession parallelly.
To promote ecological succession, the areas should no longer be completely and mechanically cleared; as much wood as possible should be left in the stand (to promote optimum soil and germ bed formation, soil moisture storage and natural protection against browsing). In private forests, the abandonment of use in disaster areas should be specifically promoted for ecological reasons and in order to relieve the burden on the timber market.

Regarding the promotion of reestablishment plantings in private forests: priority for native tree species (of regional origin); choose wide planting distances in order to leave enough space for the development of pioneer species. For the forests of the future: Minimize thinning (low-input principle), build up stocks through targeted development towards old thick trees, protect the inner forest climate / promote self-cooling function (should have highest priority due to rapidly progressing climate change!), prohibit heavy machinery, refrain from further road construction and expansion, permit and promote natural self-regulatory development processes in the cultivated forest and on (larger) separate areas in the sense of an compound system; drastically reduce the density of ungulate game (reform of hunting laws).

Like in the field of organic agriculture, which has been established since the 1980s, the crisis of our forests should be the reason today to transform at least two existing forestry-related universities. They should be turned into universities for interdisciplinary forest ecosystem management. This is a contribution not only to the further development of forestry science and silviculture in Germany, but also of global importance! The goal must be to produce wood through largely natural forest production and to start with it here in Germany, the birthplace of forestry.


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