KNOWLEDGE BASE

This study examined the reintroduced European beaver population in Sweden. At the time, reintroductions were happening with increasing frequency but few long-term studies of reintroduced populations were available. Based on the population growth pattern observed - a typical, rapid increase followed by a decline - the authors suggested some management strategies. These included allowing hunting during the population growth phase.

This study analysed beavers' behaviour and territory sizes after releasing them sequentially into a new area. Beavers released early settled into larger, richer habitats first, whilst later releases occupied smaller, poorer ones. Territorial behaviour limited beaver population density. The study also explored how territory size changed with the seasons and whether the beavers were foraging willow sustainably or not (it appeared that they were!).

Beavers were reintroduced to an area of the Netherlands, with the expectation that they may help create a mixed forest from a willow-dominated forest. However, this article explained how the beavers - although mainly feeding on them, removed only a small percentage of the willows. They also ate a disproportionate amount of the non-willow species - perhaps to maintain a balanced diet - which likely hindered forest succession. The study suggested a more natural water regime overall would likely have been needed for successful forest change. Please note, this resource is not open-access.

Scientists monitored a beaver pond system's water chemistry in the USA for just over two years. The beaver pond acted as a sink for some dissolved substances like aluminium and sulphate, but was a net source for others like organic carbon and ammonium. Some of the substances that the pond absorbs can cause acidification problems downstream, suggesting that beavers may have a helpful effect on downstream ecosystems even if they don't live there! Please note, this resource is not open-access.

This article gave an update, as of 1993, on the case of invasive beavers in Tierra del Fuego, Argentina. Suitable habitat and a lack of natural predators had allowed beaver populations to grow rapidly, colonising several islands in the Magallanico Archipelago. Their presence had transformed the forest ecosystems, creating wetlands, raising water tables, and altering the biochemical composition of riparian areas. Please note, this resource is not open-access.