KNOWLEDGE BASE

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.

Researchers worked out how to tell the age of beavers by looking at their bones. They found that beavers take a long time, up to 12 years, to fully develop their skeletons, probably because they live in water. This slow development allowed them to divide beaver skeletons into five age groups: young, middle-aged, and old adults, as well as juveniles and subadults. Alongside other ageing methods such as analysing beaver teeth, this will help studying beavers in the wild and in history.

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.

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.

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.