EDP Baixo Sabor: Reservoir Filling and Exploration Phase – Otter [2015-2020]

Study Extent

The data were collected in 50 transects in the lower Sabor river valley, its tributaries and the rivers Maçãs and Angueira, from the river mouth up to 73 km upstream, in the municipalities of Torre de Moncorvo, Alfândega da Fé, Mogadouro, Macedo de Cavaleiros, Vimioso and Bragança.

Sampling

Sampling was designed to cover the whole valley of the lower Sabor river, its tributaries, and the rivers Maçãs and Angueira. A total of 50 transects was established in the study area. The transects had a minimum lenght of 200 m and, within this distance, the survey was stopped after the detection of the first confirmed sign of presence of the species (e.g., spraints, footprints). If there were no evidences of presence in the first 200 m, the transect was extended to a maximum of 600 m, after which, if the absence of signs persisted, the species was considered absent in the transect. Each transect was performed on foot, during daytime, by one or two observers, and the riverbed and its margins were carefully searched for signs of otter's presence (scats, footprints). All scats found were identified in the field and then taken to the laboratory for dietary analysis. The survey was based on indirect signs of otter presence, because individuals of the species are difficult to observe directly, and because the presence signs (spraints and footprints) can be unequivocally identified by experienced technicians. The database only includes the initial points of the transects along a particular water line, independently of the direction of the transect.

Quality Control

All identifications were performed by qualified technicians

Method steps

1. To be completed

The taxonomic coverage of this dataset includes 1 class, 1 orders, 1 familiy, 1 genus and 1 species.

1. Chordata
   rank: phylum
2. Mammalia
   rank: class
3. Carnivora
   rank: order
4. Mustelidae
   rank: family

Data were collected along the lower Sabor river valley and its tributaries, in 50 transects, from the river mouth up to 73 km upstream, in the municipalities of Torre de Moncorvo, Alfândega da Fé, Mogadouro, Macedo de Cavaleiros, Vimioso and Bragança.