Beaver Populations By Type in Europe: 1900 vs. 2021

The two maps above show Europe’s beaver population in 1900 compared to 2021.

They both come from this wonderful video by Qarol Mapping:

The Eurasian beaver (Castor fiber) was hunted to the brink of extinction for its fur and castoreum, leaving only around 1,200 individuals surviving across eight isolated populations ranging from France to Mongolia by 1900.

However, widespread reintroductions across Europe, means there is now an estimated population of at least 1.5 million in 2021.

But what’s going on with North American beaver (Castor canadensis) population in Finland?

North American beavers were introduced to Finland in 1937, initially intended as a reintroduction effort after the local extinction of Eurasian beavers.

At the time, it was not recognized that the North American beaver was a separate species.

From an initial group of seven individuals, the population expanded rapidly, reaching approximately 12,000 animals within 64 years.

By 1999, around 90% of Finland’s beavers were identified as North American.

Despite their introduction, North American beavers are not universally viewed as invasive, since their ecological role in Europe closely mirrors that of Eurasian beavers, which have not returned to the region naturally.

To manage their numbers, hunting licenses have been issued.

A 2010 report concluded that, although the current American beaver population in Finland poses no significant ecological issues, their higher reproductive rates and tendency to build slightly larger dams could lead to problems if their range expands eastward into Russia.

However, such an expansion has not yet been observed.

Below you can see the map for 1900 vs 2021 in more detail:

1900

2021

Differences Between the Eurasian and North American Beaver

Feature	Eurasian Beaver (Castor fiber)	North American Beaver (Castor canadensis)
Size & Weight	Slightly smaller and lighter; typically weighs 11–30 kg.	Slightly larger and heavier; typically weighs 16–32 kg.
Fur	Generally lighter-colored, grayish-brown fur.	Darker, reddish-brown fur.
Skull & Head Shape	Longer, narrower skull with a less prominent nose.	Shorter, wider skull with a more prominent, rounded nose.
Tail Shape	Narrower, less oval-shaped tail.	Broader, more oval-shaped tail.
Chromosome Count	48 chromosomes.	40 chromosomes.
Dam Building	Smaller dams and lodges.	Larger dams and lodges.
Reproduction	Smaller litter sizes (average 1–3 kits).	Larger litter sizes (average 3–4 kits).
Behavioral Traits	More cautious and wary of humans; less adaptable to human-altered landscapes.	More adaptable and somewhat more tolerant of human presence.
Range	Native range extends from Western Europe to East Asia (historically widespread, but reduced).	Widely distributed throughout North America (Canada, USA, Mexico).
Conservation Status	Historically near extinction but recovering in parts of Europe and Asia.	Common and abundant, not threatened.

What do you think of this map?