Mammals in MZNA-VERT: biology of Arvicola sapidus in Navarra. PhD project, Juan Manuel Garde

Study Extent

Ribera Alta is a geographic area located in the south of Navarra dominated by an agricultural landscape mixed with natural vegetation coverage consisting mainly on mediterranean scrubs patches and black pine repopulations (Rivas-Martínez, 1987). Surveys took place at Aragón’s riverbank as it passes through Mélida. It is a riparian forest formed by elms, black plopars (Populus nigra), ashes (Fraxinus angustifolia) and willow trees. Reed beds are also important as they constitute shelter and source of food for the water vole.

Sampling

Main sampling effort was conducted from October 1984 to December 1986 mainly once or twice a month. Five sampling sites were selected but most of the material comes from Mélida, specifically from riparian forest of Aragón river. Traps were placed in areas were activity of A.sapidus was observed (e.g. scats). These areas were commonly tracks used by this specie. Each trapping event last one day and traps were checked twice a day: at dawn and twilight. Traps were not baited to avoid attracting other species. All specimens captured were brought to the laboratory for further studies.

Quality Control

All specimens are deposited in the Museum of Zoology of the University of Navarra (MZNA, Pamplona, Spain) in the ‘Biology of Arvicola sapidus in Navarra’. All specimens of A.sapidus were sexed and identified in by Juan Manuel Garde. Other small mammals captured during the sampling were transported as well to laboratory and identified using suitable literature (Gosálbez 1987). Scientific names have been validated according to Mammal Species of the World (Wilson and Reeder 2005, Palomo et al. 2007). Unique catalogue numbers were assigned to each specimen. Coordinates in UTM/MGRS were transformed to geographic system. The consistency of all records was checked by visual inspection overlapping coordinates with a map of Navarra using GIS (Chapman 2005) and their uncertainty was calculated in metres using the point-radius method.

Method steps

1. Specimens of A.sapidus were dissected in laboratory conserving skin, skull, fore and hind limbs and some tissues (crystallines, testicles, ovaries and smear from testicles). First, skin was removed, cleaned with soap and dried using sodium borate. Then, each skin was mounted on a cardboard and stored. Secondly, each specimen was dissected separating skull, limbs and tissues previously listed. Skeletons parts were boiled and then, flesh was separated from them. Tissues were conserved in alcohol (ETOH). Biometric data were also taken from most of specimens of water vole. Measures were taken following rules from Comisión de Biometría (1972). Skulls from the other species were prepared following the same protocol than in the case of A.sapidus. Information of each specimen was incorporated to MZNA database (Zootron v4.5, Ariño 1991).

The collection includes records of 6 species belonging to Rodentia and Soricomorpha orders but it is mainly composed of specimens of A.sapidus (Cricetidae, Rodentia).

1. Animalia
   rank: kingdom
2. Chordata
   rank: phylum
3. Mammalia
   rank: class
4. Rodentia
   rank: order
5. Soricomorpha
   rank: order
6. Cricetidae
   rank: family
7. Muridae
   rank: family
8. Soricidae
   rank: family
9. Apodemus
   rank: genus
10. Arvicola
    rank: genus
11. Crocidura
    rank: genus
12. Microtus
    rank: genus
13. Mus
    rank: genus
14. Rattus
    rank: genus
15. Apodemus sylvaticus
    rank: species
16. Arvicola sp
    rank: species
17. Arvicola sapidus
    rank: species
18. Crocidura russula
    rank: species
19. Microtus sp
    rank: species
20. Mus spretus
    rank: species
21. Rattus norvegicus
    rank: species
22. Rattus rattus
    rank: species

All specimens were sampled in Ribera Alta de Navarra (Spain), mainly in the Aragón’s river bank as it passes through the locality of Mélida (Navarra).