Reading: Summary, Note & Table Completion: Question 2

Between 2009 and 2022, several regional water authorities in northern Europe reintroduced Eurasian beavers into upland river catchments as a low-cost method of reducing flood risk downstream. Unlike engineered flood barriers, beavers achieve this passively: by felling small trees and packing branches, mud and stones across a stream channel, a single family builds a dam that can raise the water level behind it by up to a metre, creating a pond that stores rainfall during storms and releases it slowly over the following weeks. A catchment containing a dense network of beaver dams can, according to monitoring data collected over a decade, reduce the height of a downstream flood peak by as much as sixty percent compared with an undammed stretch of the same river.

The ponds created by beaver dams bring benefits beyond flood control. Sediment and agricultural runoff carried by the stream settle in the still water behind each dam rather than being washed straight into rivers further downstream, measurably improving water clarity. The resulting wetland habitat also attracts a wider range of species; surveys of reintroduction sites recorded increases in populations of dragonflies, amphibians and wading birds within only a few years of the beavers' arrival, since the varied depths and slow-flowing margins of a beaver pond suit species that cannot tolerate a fast, uniform river channel.

Reintroduction has not been without friction. Landowners farming close to a river have occasionally objected to beavers felling mature trees or flooding low-lying pasture, and in a small number of cases dams built too near farmland have had to be partially dismantled by wildlife officers. To track the animals' movements and dam-building activity without disturbing them, most reintroduction projects now rely on a network of motion-triggered camera traps positioned along the riverbank, supplemented by occasional live-trapping to fit individual beavers with radio tags. Project managers describe the approach as a compromise: the beavers are left almost entirely to their own devices, while camera-trap footage allows researchers to intervene quickly if a dam threatens nearby property.

Complete the table below. Choose NO MORE THAN TWO WORDS from the passage for each answer.