EDP Foz Tua: Bat Habitats - Ecological Monitoring Program (PME) and Program of Mitigation/Compensatory Measures (PMC, MC12H) - Exploration Phase (2018-2020)

Study Extent

The data were collected within a 5-km radius buffer around the lower valley of River Tua (Northeast Portugal), up to 40 km from the mouth, in the municipalities of Alijó, Carrazeda de Ansiães, Vila Flor, Mirandela and Murça.

Sampling

Sampling was designed to cover all suitable foraging habitats for bats in the study area. A stratified sampling procedure was used, with the number of samples allocated to each habitat in proportion to the area occupied and/or its significance for bats. A total 0f 60 sampling points (56-PME and 4-PMC) was set in natural woodlands (10), forest plantations (mostly Eucalyptus and Pinus), (10) river margins (9), shrublands (9), orchards/olive orchards (6), vineyards (6), dryland crops (7) and cliffs (3). Each point of PME was visited monthly (March - October) from 2018 to 2020 and each point of PMC was visited monthly (July - August) from 2018 to 2020. Acoustic sampling was made within ± 3 hours of sunset, beginning 30 minutes after it. Each point of PME was sampled for 10 consecutive minutes and 15 minutes the points of PMC. The detection of the specimens in flight was made with a bat detector (Pettersson Elektronik, D240X model), with a frequency range of 10-120 kHz. The detector was connected to an automatic digital recorder (model Zoom H2n) which saved the recordings in a “Wave” format, at a frequency of 44 kHz and at an expanded mode of 10x, making them audible to the human ears while, at the same time, preserving the original acoustic characteristics. The analyses of bat sound records used the manual/traditional methodology based on the the software “Batsound Pro – Sound Analysis”, from Pettersson Elektronik. This software generates graphics (oscillograms, sonograms and power spectrums) that allow the identification of the detected species by comparing them with those available in reference bat sound libraries. The acoustic variables usually employed to manually identify the sounds are (1) the structure of the pulse, (2) the frequency of maximum energy (kHz), (3) the range of frequencies (kHz), (4) the pulse duration (ms), (5) the interval between pulses (ms), and (6) the pulse repetition rate (Hz). The exact identification of the bat species by sound analysis is not always possible, due to problems in detectability and/or identifiability. In the context of this work, whenever it was not possible to perform the identification until the species, the binomials, multinomials or genera to which the identification was possible were considered to be present. Thus, the presence of all species constituting these phonic groups (or “species complexes”) was considered possible.

Quality Control

All individual identifications were performed by qualified technicians

Method steps

1. To be completed

The taxonomic coverage of this dataset spans 1 phylum, 1 class, 1 order, 4 families, 10 genus and 13 species positively identified. Additionally, a set of 8 potential species may be present in the 23 “species complexes” identified.

1. Chordata
   rank: phylum
2. Mammalia
   rank: class
3. Chiroptera
   rank: order
4. --------------
   rank: family
5. Miniopteridae
   rank: family
6. Molossidae
   rank: family
7. Rhinolophidae
   rank: family
8. Vespertilionidae
   rank: family

The data were collected within a 5-km radius buffer around the lower valley of River Tua (Northeast Portugal), up to 40 km from the mouth, in the municipalities of Alijó, Carrazeda de Ansiães, Vila Flor, Mirandela and Murça.