KNOWLEDGE BASE

In this study, researchers analysed the genes of Eurasian beaver populations from across Eurasia. They focused on 8 'relict' populations that survived the peak of beaver overhunting in the late 1800s. They found 16 types of gene pattern, none of them shared by more than one of these populations. However, these 16 patterns can be grouped in two main genetic lineages, eastern and western, which were possibly formed during the last ice age. The study suggests managing each population as a distinct unit and offers guidelines for future conservation efforts.

This text charts the history of the North American beaver from before European colonisation to the present. It explains how overhunting led to a severe reduction in beaver numbers, beaver ponds, and the amount of sediment that those ponds had been stopping from flowing downstream. Beaver populations have partially recovered to around one-tenth of their prior levels. Today, beaver dams still trap significant sediment. Beaver dam collapses are more common than many people think, and the collapses can cause floods and infrastructure damage.

This article shows how a core ecological metric like population density varies across different scales and landscape features. They found that the larger the area, the lower the population density. The study, based in Canada, demonstrates this with beaver populations but goes into more detail analysing the population density of grey squirrels.

Researchers investigated the presence of two parasites in beavers from Massachusetts, USA. 62 blood samples were collected and tested showing a low overall prevalence: 10% of samples were positive for T. gondii and 6% for S. neurona. The presence of these parasites in beavers suggests they have been ingesting it from nearby water or foliage, possibly as a result of contamination by cats or opossums.

This article reports on three occasions between 1999 and 2004 where Alaskan beavers were seen feeding on Chinook Salmon carcasses. They were seen actively seeking out carcasses, swimming with carcasses in their mouths, or using their forefeet to handle and chew the salmon. Many other plant-eating mammals are known to occasionally eat meat but this had never been reported before for beavers. Although unusual, the authors suggested this may be a common strategy of Alaskan beavers to make the most of the seasonal protein source provided by salmon runs.