KNOWLEDGE BASE

Castoreum extract is a natural substance derived from beaver scent glands. This article assembles the research on its toxicity as a food additive. Based on the limited current data, consuming castoreum extract at current levels is deemed safe. Its long-term use throughout history without reported adverse effects supports this conclusion. It is regarded as safe by regulatory bodies. Overall, using castoreum extract at current levels poses no safety concerns. Please note, this resource is not open-access.

This study tested the impact of Eurasian beavers browsing on willow plants in winter. They simulated beaver browsing by pruning willow shrubs in February and comparing the shoots with those of shrubs that had not been pruned. The new shoots were tested in May and November. In May, pruned shoots were more nutritious and were preferred by beavers. In November, there was no difference in nutrition nor in beaver preference. This suggests that, after browsing, willows prioritise regrowth rather than any type of defense mechanism.

Researchers explored how wood frog populations respond to different types of beaver pond in Canada. They found that older beaver ponds hosted more male frogs, likely because they had less tree cover, warmer water, and higher oxygen levels. Protecting beavers and their habitats could help maintain healthy amphibian populations in the high-latitude pine forests. Please note, this resource is not open-access.

One challenge of managing conflicts between humans and beavers is the fact that people's views vary and change over time. In the USA, after a law was passed banning certain beaver traps, surveys were carried out to understand public opinion. This article reports on these surveys. Overall, people had positive views of beavers but those who had had negative experiences with beavers held less favourable views. The authors suggest that conservation efforts should be responsive to changing public attitudes. Please note, this resource is not open-access.

Between 2002 and 2004, feces from 62 beavers in the USA were tested for certain parasite species using microscopy and genetic analysis. The study showed that 6.4% of the beavers, all young ones, had these parasites.