This interesting species of duck nests in hollows or burrows under trees, and sometimes on the ground, always near water. The nest can be even several hundred meters away from the nearest water reservoir. After hatching, the young jump out of the hollow to the ground and are led by their mother to the nearest river. In the summer you can see the mother carrying many of her offspring on the back. Goosanders in Poland are sparse, but for some time their range from Scandinavia has been extending through northern Poland towards the south, mainly along river valleys. The greatest threat to this species is the cutting down of old hollow trees, which is associated with the loss of nesting sites. Predators such as cats, martens, foxes and raven birds are also a significant threat. To prevent this, you can hang special nesting boxes for these birds, which should be properly secured against the entry of predators. Mergansers can be observed every year in Roztocze, mainly in winter in herds, I encourage you to go on field trips (Bird & Car) because observing these interesting birds is a great joy.