At the sources of the Biferno, among the tufts of aquatic plants, the trout dig their own beds of scrub, bringing to light the white gravel. The individuals seen in the video are mostly males manning the breeding site and fighting for the best position while waiting for the female. The female is present and is the one that is stationed just downstream from the mound of gravel. Other females before her have moved that gravel with tail strokes and the reproducers concentrate precisely on the nests already cleaned by the earliest females. Competition for breeding sites is ongoing, and late breeding males can damage previous spawns. This is also why it is so important to redevelop the habitats, increase the available surface and break down the barriers that prevent native trout from reaching further sites suitable for reproduction.