KNOWLEDGE BASE

Much of the research exploring Eurasian beavers' impacts on fish had focussed on beavers located in forested areas. However, in Russia, many beavers live in steppe (grassland) environments. Some had theorised that beavers' effects on fish in these areas may be less than in forests since beaver population density was lower, but this paper gathered real data to test that theory. The results showed that beaver-modified habitats in this environment supported lower fish diversity and biomass compared to beaver-free areas. However, the researchers suggested that long-term beaver population stability might have a more positive impact.

Following the revival of Sweden's beaver population over the course of the last 100 years or so, this study sought to survey the parasites hosted by beavers across the country. Scientists only found five types of parasites after testing 30 beavers from around the country, reflecting the low levels of infection found in the original Norwegian population. Higher levels of infection were found in beavers from southern Sweden where temperatures are warmer.

This short note reported that Eurasian beavers had returned to Bulgaria, where they had been absent for over 150 years. The beavers were detected in the north of the country and the document contained two photos of the evidence gathered. By publishing this evidence, the authors aimed to inform the public and urge authorities to protect the species and its habitat, having noted that some local residents were harbouring a "negative attitude" towards the animals.

Acquiring a territory and a mate are crucial to beavers' reproductive success. These are often studied as independent phenomena but, for the beaver, they are not so easily separated. Here, scientists studied these phenomena simultaneously in a high-density Eurasian beaver population in Norway. The results showed that territory acquisition in this context depended more on a beaver's competitive ability (i.e. being bigger, or knowing the area better, than the other beaver) than on them being compatible with a potential mate. The text also discussed the reproductive trade-offs related to this dynamic.

Researchers tested whether Eurasian beavers' foraging habits differed according to sex. By following the activities of 41 beavers in Norway, they found that, while males and females spend similar amounts of time foraging overall, females spend more time in the lodge during spring and eat more aquatic vegetation. Males tend to eat more shrubs and trees throughout the year. These differences may help beavers adapt to the needs of reproductive cycles.