In an article by “Welt.de” from May 2025 a squirrel aid-worker (in Berlin, Germany) is being quoted saying: “Es ist dramatisch – bei den Eichhörnchen ist der Beginn des Aussterbens da” (English: “It’s dramatic – the squirrels are on the verge of extinction”). This claim turns out to be mostly false.
In order to verify the claim and ensure accurate reporting, we reached out to Tanya Lenn directly, as well as several leading researchers in the field, including Dr. Craig Shuttleworth and Dr. Lucas A. Wauters. Their insights form the basis of the expert consensus presented here. We also reached out to a representative of the DPA and received the original publication in order to be able to accurately trace the path of the claim.
The claim dissected
The original claim stems from a DPA feature story with the squirrel aid worker Tanya Lenn from Berlin, Germany. The DPA (German press agency) regularly publishes stories and many German news outlets have a contract allowing them to license and re-publish these reports sometimes with minor changes on their own websites. This was also the case with this claim: DPA published the feature story with Lenn on April 28, 2025 and Welt.de republished it with minor but impactful changes in the first week of May 2025 on its own website.
The headline of the article by Welt.de states: “It’s dramatic – the squirrels are on the verge of extinction”. According to both the DPA report and the Welt.de article, Lenn is also claiming that squirrels suffer from prolonged droughts and it can cause them to fall from trees because of dehydration – and that higher temperatures in winter months are negatively affecting the hibernation cycle of squirrels.
In the original story by DPA, Tanya Lenn’s initial claim was slightly different to the headline of the Welt.de article. It states: “Es ist dramatisch – bei den Hörnchen ist der langsame Beginn des Aussterbens da” (English: “It’s dramatic – the squirrels are slowly beginning to die out”). It was also immediately followed by a note saying that the squirrels won’t be extinct in the near future, however it is not clear if the latter statement was made by Tanya Lenn herself or if it is additional context added by the DPA later.
The contextualization was omitted, however, when the report was re-published by Welt.de, leaving out the important word “slowly” in the original quote. With that the quote is dramatized and misses crucial context from the original story.
By definition, extinction means “the dying out or extermination of a species” and it can occur “when species are diminished because of environmental forces” (Britannica), such as habitat destruction, climate change, or endangerment by invasive species.
However, the term “extinction” usually refers to the complete disappearance of the species on a global scale. The quote from Lenn, published and shortened in the headline of “Welt.de” claiming that “the squirrels are on the verge of extinction”, evokes a sense of imminent species extinction. This does not align with current assessments made by conservationists.
While the claim made by Tanya Lenn only talks about “squirrels” in general, biologists differentiate between two main squirrel species in Europe: grey squirrels (Sciurus carolinensis) and red squirrels (Sciurus vulgaris). Grey squirrels are resident in The United States of America and Canada but were introduced to Italy, Ireland and the UK in the past century. Red squirrels are resident in the whole region of Eurasia. Both of their population sizes are stable, according to the International Union for Conservation of Nature and Natural Resources (IUCN).The IUCN regularly publishes a list of the conservation status of animal, fungi and plant species, called the Red List. The conservation status of both squirrel kinds is listed as “Least Concern” in this list. In both cases, the IUCN argues that the species have a large population size and a wide distribution. This finding suggests that conservationists would heavily disagree with the term extinction used in the context of squirrels of any of the two species.
An overview of the distribution of red squirrels according to IUCN data can be found here.
Population size of squirrels is unknown
There is no reliable data on the current total population of red and grey squirrels in Europe. Some projects, such as the German citizen science project “squirrels in Bavaria” by NABU (Nature Conservation Association), try to collect such data on a regional level with the help of citizens who use an app to record sightings of squirrels. Citizens and scientists in Berlin have also participated in a data collection project, according to a report by the Berliner Abendblatt in 2022. The mentioned project has found that there has been no significant decline in the red squirrel population in Berlin, stating that the sightings are still “fairly frequent”. This means that even on the regional level, there seems to be no scientific evidence that supports Lenn’s claim. As Tanya Lenn is from Berlin, Germany it is also important to note that currently only the red squirrel is resident in Germany and, according to NABU (German Nature Conservation Association) there are no reports on grey squirrel populations in the country.
Grey squirrels pose a risk for red squirrels
However in other European countries such as the UK and Italy there are certain things affecting red squirrel populations heavily. One is the extinction threat that invasive grey squirrels pose to native red squirrels. A recent systematic review of all the literature regarding the competition and interactions between red and grey squirrels suggests that the replacement of native red squirrels by the invasive grey squirrel in Europe “is one of the best documented cases of the devastating effects of biological invasions on native fauna” (Wauters et al., 2023, p. 1).The invasive grey species originally came from the American continent and has been introduced to the European continent since the mid-20th century. In regions with a high population of grey squirrels, the red squirrels are heavily affected and red population size declines rapidly, according to studies in regions such as northern Italy (Bertolino & Genovesi, 2003) and the UK (Bertolino et al., 2016). While there are risks for the red squirrel in specific regions, where the grey squirrel is habitant, in Germany there are no reports on any existing grey squirrel population making the claim incorrect on a national level.
The squirrel poxvirus
Grey squirrels are a danger to red squirrels because they often carry a disease, the squirrel poxvirus (SQPV) and infect the red individuals. Typical transmission routes are direct contact and body fluids (Collins et al., 2014). This is an imminent risk to red squirrels as it heavily affects the health of red squirrels, often killing the infected individuals (Carroll et al., 2009). Their grey counterpart, however, does not appear to be affected nearly as much by the virus and is therefore considered to be only a reservoir host for the virus.
In 2017 scientists also discovered a new aggressive poxvirus in and around Berlin, calling it the Berlin squirrel poxvirus. A report by the German Leibniz-Institute for Zoo and Wildlife Research suggests that the Berlin squirrel poxvirus is mostly a danger to young red squirrels. The Berlin squirrel poxvirus therefore could have been a cause for Lenn’s observation of squirrels being weak but is physically isolated to the area around Berlin, Germany.The claimed threat for red squirrels could be a future one, as grey squirrels are likely to expand all over Europe in the foreseeable future, according to a study (Bertolino & Genovesi, 2003, p. 351). Although the International Union for Conservation of Nature and Natural Resources (IUCN) argues that this development is not currently visible in the population size of grey squirrels, their expansion in Eurasia could be a threat to the population size of red squirrels, even in Germany. While there is evidence of a threat to red squirrels in some regions, it is not accurate to say that this will extend to all squirrels.
Effects of climate change
While Tanya Lenn also cites a change in climate as a reason why squirrels are at risk, it is worth taking a look at the research.
A 2018 study on red squirrels found that population growth rates of red squirrels are lower in regions where winters are warming more rapidly. The authors suggest that changes in the environment may be contributing to red squirrel decline (Turkia et al., 2018), this matches the claim by Lenn regarding the prolonged droughts. A more recent study from 2023 projects that, under both the most optimistic climate change scenario (“SSP126”) and the most pessimistic scenario (“SSP585”), grey squirrel populations are likely to continue expanding, possibly displacing red squirrels in some regions in Europe (Nie et al., 2023) mainly because of the squirrel poxvirus.Climate change also has a significant negative impact on biodiversity and affects trees in their seed production, studies find (Bellard et al., 2012; Bogdziewicz et al., 2020). When fewer seeds are produced, there is a mismatch between the availability of resources and the needs of consumers such as squirrels. The lack of sufficient food options causes squirrels to reduce their reproductive activities, studies show (Williams et al., 2014). Altering the timing of tree growth and squirrel reproduction, warmer weather causes further mismatches that also have a secondary impact by introducing a higher juvenile mortality, according to a study (Selonen et al., 2016). By stating that higher temperatures in winter months are negatively affecting the hibernation cycle of squirrels and therefore the overall fitness of the species, Lenn seems to be correct, as this part of her claim can be supported by science.
How expert consensus frames the threat
“In order to say that [squirrels are becoming extinct], you would have to have a lot of long-term data. To determine if an animal died from dehydration, you’d need a pathologist,” says Dr Craig Shuttleworth, a research fellow on squirrels at Bangor University in Gwynedd, Wales. In the interview he also states: “In ‘95, I was working in Liverpool, we had a really hot summer and what I noticed about the squirrels then was they began to lose condition and a lot of them had skin infections of autumn mites. But I didn’t notice a decline in the population associated with that dry weather. There was still plenty of food.”
Dr. Lucas A. Wauters, a researcher at the University of Insubria, confirmed via email: “There is no evidence to show that the squirrels are slowly going extinct. The red squirrel however does face a regional threat in areas invaded by the grey squirrel.”
Conclusion
While the claims of Tanya Lenn might have been true on a local level, her phrasing of the quote and changes made by Welt.de in particular turned a personal and regional observation into a misleading general claim that is contradicted by science.
What the German squirrel aid worker appears to be describing is not extinction in a strict biological sense, but rather her personal observation of a gradual population decline of red squirrels that are local to Germany and an increased struggle for survival due to various environmental stressors. These include warmer winters, shifting food availability, changes in reproductive activity, and habitat loss – all of which can lead to regional population decline.
However this is only the case for the red squirrel population – grey squirrel population is expected to increase in the near future, according to numerous studies. In addition, the Berlin squirrelpox virus may have contributed to Lenn’s regional observation of a change in the health and size of local red populations.
A correct claim would have been that the red squirrel is threatened in some regions of Europe by the invasive grey squirrel, whose population size is projected to increase and which therefore poses a future threat to the red squirrel in other regions of Europe.
RESEARCH | ARTICLE © Louis Göllner, Hochschule der Medien, University of Applied Sciences, Stuttgart, DE –
Timon Weiß, Jade Hochschule, University of Applied Sciences, Wilhelmshaven, DE – Marios Foutiou, Haaga-Helia University of Applied Sciences, Helsinki, FI –
Lea Prawit, Jade Hochschule, University of Applied Sciences, Wilhelmshaven, DE –
Jelmer de Vries, Hogeschool Utrecht, University of applied sciences, Utrecht, NL –
Ynske Meyes, Thomas More, University of Applied Sciences, Mechelen, BE
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