ALT Beaver dams act as wildlife bridges! Image 1: A camera trap image of a beaver gnawing a fallen branch. The image is black and white and was clearly taken at night. A beaver dam is visible in the background, and the beaver is in the water held back by the dam. Image 2: A camera trap photograph of a red squirrel crossing the beaver dam, clearly the same location, but during daylight hours and in colour. The squirrel is mid leap crossing towards the camera, tail up.

ALT Text: Daniel Arah, an MSc student from the University of Glasgow - who completed a placement year with Beaver Trust - has shared the results of a camera-trapping study on beaver dam crossings. One aspect of Daniel’s research assessed whether beaver dams act as bridges for terrestrial mammals during seasonal high-water conditions. It compared beaver dams with control structures. Graph: A bar chart. Y axis reads 'Detections per 100 trap nights' and has units 0-20. The bar on the left is labelled 'control' it is the shorter bar (reaching approximately 4). It is divided into two colours -Brown for deer and orange for foxes. The deer section is largest (approximately 3 units). The bar on the rights is labelled 'Dam' it is much taller, reaching almost 20. It is divided into six colours, representing Fox, Mink, Otter, Pine martens, Red squirrel, and Rodents. Pine martens are the largest section (roughly 10 units) The chart illustrates that beaver dams were the preferred structure.

ALT Text: Pine martens crossed beaver dams more frequently than any other terrestrial mammal, but they weren’t the only mustelid to use the beaver-engineered bridge... Images: Two camera trap images of pine martens crossing the dam towards the camera, they are black and white, clearly taken at night. The top image shows a pine marten carrying an egg. In the bottom image the pine marten has its head to the ground, facing the camera, you can see its eyes, ears and body, but its nose is out of frame. The dates on the photographs indicate these photographs were taken on consecutive nights (01-02/09/2022)

ALT Text: Otters (pictured above) and American Mink both used the beaver dams to cross the water. Instances of otters swimming past the camera traps were also recorded, but these were not included in the results. A total of six beaver dams were monitored for mammal crossings during the study. Across these and the control structures, a total of 308 nights of camera trapping contributed to the dataset. Image: A camera trap photo shows the rear half of an otter as it crosses the dam away from the camera. Its forelegs and head are disappearing into the darkness, as the image was taken at night. Its tail hangs over the dam.