KNOWLEDGE BASE

This paper compared skulls of 2 ancient beavers with those of modern beavers in Poland. It found that ancient beavers had notably larger skulls than modern beavers of the same age. This is precisely set out by measuring different parts of the skull, including a part called the sagittal crest. Tables 3 and 4 set out these results in comparison to modern beavers.

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 text described how and why grassland bird populations in North America have declined, citing habitat loss and changes in ecological processes. Beavers, along with grazers like bison and prairie dogs, helped maintain open grasslands prior, but have suffered due to over-hunting. Understanding these natural processes was said to be crucial for informing bird conservation efforts, whether on natural habitats or on working lands like farms.

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.