Eurasian beavers were almost hunted to extinction in the early 20th century.Only 1200 individuals survived in 8 small populations.Since then,protection and reintroduction have caused their numbers to rise to over 1 million individuals.In Flanders,Belgium,beavers repopulated a landscape with a high density of humans.However,the beavers semi-aquatic and primarily nocturnal activity make it hard to study their behavior.Radio-tracking and visual observations have been performed in a number of studies,but both methods are time intensive and are often based on a small number of individuals.As an addition to other methods,we examine whether camera traps are a useful tool to study beavers.Camera traps have proven their use for studying large,mostly terrestrial mammals.However,knowledge concerning their use and usefulness for semi-aquatic mammals is very limited.Camera traps were deployed in 34 known beaver territories in Belgium.During more than 4000 camera days,1907 independent beaver recordings (counting only 1 beaver recording per location per hour) were registered,representing 41%of all mammal recordings indicating that directional placement of the cameras works.Differences in position of the camera trap (near the burrow,a freshly gnawed tree,running tract,dam,feeding location,water) significantly influenced the recording success.The beavers general activity pattern was based on examining the proportions of recordings over a 24 h period and confirmed the mainly crepuscular and nocturnal activity.Based on the activity pattern we observed minor seasonal differences and an increased activity at high moonlight intensities in this temperate region in Europe.