KNOWLEDGE BASE

By chemically testing the outer hair of gray wolves in Canada, scientists were able to estimate the relative proportion of different prey items in the wolves' diets. Beavers made up around 8% of the wolves' diet overall, but for individual wolves it made up between 0% and 25%. Given that wolves' often hunt and eat together, the scientists had not expected such high variability in diet between individual wolves.

This report contains an analysis of how beaver conservation efforts have fared in Oregon, USA. Beavers play a vital role in creating habitat for juvenile coho salmon and these beaver conservation efforts had the ultimate objective of supporting salmon populations. In 1997, a programme to discourage beaver trapping began. This was successful because fewer beavers were being trapped but there had not been a clear increase in habitat for salmon.

Traditional theories suggest animals defend the smallest territory which contains enough resources for reproduction. However, in social animals, territory patterns may become more complex. This study explores this idea for beavers, showing that their territories don't just depend on resources but also on when pairs actually arrived in the territory - the pairs that arrived earlier got the bigger territories!

This study examined how light influences the levels of a type of mercury and dissolved organic carbon (DOC) in different lakes and wetlands over the course of a day (and night). The different freshwater habitats, amongst them a beaver pond, were chosen to represent different DOC levels. The scientists found a strong relationship between levels of this mercury, DOC, and sunlight, mediated by the ultraviolet light in sunlight. The text provides detail on, and a chemical explanation for, this relationship.

In Alaska, coho salmon return from the sea to freshwater to spawn and die. This study tested the theory that this process enriches freshwater beaver ponds with nutrients from the sea, supporting food webs and benefitting the young salmon. They tested ponds under a variety of conditions and showed that the spawning salmon can provide up to half of the carbon and nitrogen that the young salmon need, making sure that the young salmon survive. Please note, this resource is not open-access.