EDP Foz-Tua: Small Mammals - Complementary Studies [2010] & Monitoring Ecological Program [2011]

Study Extent

The data were collected within a 5-km buffer around the lower Tua River valley (Northeast Portugal), up to 50 km from the mouth, and in Ferradosa stream (Douro sub-basin) in the municipalities of Carrazeda de Ansiães, Vila Flor, Alijó, Murça and Mirandela.

Sampling

Sampling was designed to cover the main habitat types for small mammals (fallows, cork-oak woodlands, bushes, riverine, abandoned orchards, reedbeds, juniper woodlands, chestnut woodlands) in and around the lower Tua valley affected by the Foz-Tua dam and in the Ferradosa stream (Douro sub-basin). Each sampling plot was visited once during three consecutive days between February-March and October-December 2010 (Complementary Studies) or October 2011 (Ecological Monitoring Program). In January-February of 2010 a total of 29 sampling points were established in the framework of the Complementary Studies of the Foz-Tua dam to provide a preliminary assessment of the small mammal fauna in the area. These plots served as a baseline for the sampling grid of the Ecological Monitoring Program of this group, which was tested in October-November 2010, with 19 points (of which 14 were effectively used) set in a 2x2 km UTM grid (one plot per square) centered in the lower Tua River valley in the area affected by the dam. Based on the results of this experience, a final grid of 19 sampling plots (of which 17 were effectively used) was established in each 2x2 km square (and in three additional points located in the Ferradosa stream), in October 2011. Each plot was selected in function of its habitat suitability for small mammals, and a preliminary inspection looking for signs of the presence of small mammals (tracks, feces, latrines) was performed. When this inspection was positive, the information was recorded and the plot was earmarked for a capture session. Each capture session consisted in the installation of lines of 25 “Sherman” traps distributed every 2-5 m in open areas and 15 m in closed habitats (e.g., bushes and woodlands), covering the maximum number of suitable habitats in the sampling plot. Traps remained set for three days and three consecutive nights and during their activation period they were baited with apple, carrot and commercial cat food (for Soricidae) and were covered with vegetation carded cotton, to provide food and thermal comfort for captured individuals, respectively. Each trap was controlled at least twice a day (one in the morning and another in the late afternoon). All the captured specimens were administered with light volatile ethyl ether anesthesia, to ensure a correct and safe manipulation procedure. Each specimen was individually assigned a temporary marking (haircut), aiming to recognize the animal in the event of a recapture situation, aged and sexed (with the exception of shrews when non-lactating), measured and subsequently released. The following biometric parameters were taken: body length, tail length, hind leg length, ear length and weight. All identifications were made with appropriate keys (Gonçalves, 2006) and field guides (Blanco, 1998). The captures were carried out under the License No 378/2010 / CAPT, issued on October 26 2010, by the Institute of Nature and Forests Conservation (ICNF) to the senior field technician.

Quality Control

All identifications were performed by qualified technicians

Method steps

1. To be completed

The taxonomic coverage of this dataset spans 1 phylum, 1 class, 2 orders, 7 families, 8 genera and 10 species.

1. Chordata
   rank: phylum
2. Mammalia
   rank: class
3. Rodentia
   rank: order
4. Eulipotyphla
   rank: order
5. Muridae
   rank: family
6. Cricetidae
   rank: family
7. Soricidae
8. Gliridae
   rank: family
9. Erinacidae
   rank: family
10. Sciuridae
    rank: family
11. Talpidae
    rank: family

The data were collected within a 5-km buffer around the valley of the River Tua (Northeast Portugal),up to 50 km from the mouth, in the municipalities of Carrazeda de Ansiães, Alijó, Murça, Vila Flor and Mirandela.