Dataset of Passerine bird communities in a mediterranean high mountain (Sierra Nevada, Spain)

Study Extent

This dataset covers four representative habitats within Sierra Nevada mountain range: Pyrenean oak forest , thorny thickets on the edge of the forest, common juniper and Spanish juniper scrublands and high-summit ecosystems. These ecosystems were selected based on criteria of singularity and ecological functionality in the context of Sierra Nevada (Barea-Azcón et al. 2012, 2014) and can be described as follow: - Pyrenean oak forest: Mediterranean woodland composed mainly of relict Quercus pyrenaica and some dominant scrubland species (i.e. Berberis hispanica, Prunus ramburii, Rosa canina, Crataegus monogyna and Adenocarpus decorticans). These forests show strong evidences of past management that determine their current structure and diversity. These management is mainly based on charcoal, pastureland creation, and wood production until the 1950s, so that the current trees are mostly resprouts of 60-70 years old. The target localities (n=4) are located at an average elevation of 1650 m a.s.l. (1600-1750 m a.s.l.) and are distributed in the south, west, north and east slopes of Sierra Nevada, reflecting all the ecological conditions of the Pyrenean oak forest in the study area (Pérez-Luque et al. 2013). -Thornscrubs: Typical areas dominated by thorny thickets on the edge of the forest or as result of recent colonization of abandoned arable lands. Berberis hispanica, Prunus ramburii, Rosa canina, Crataegus monogyna are dominant but other species as Lonicera arborea or even Sorbus spp. This open habitat is very important for breeding birds in the study area and also for winter visitors due to a great production of fruits from the end of the summer to the beginning of winter. Transect (n=4) in this habitat are located between 1450 and 2060 m a.s.l. (average: 1790 m a.s.l.). -Common juniper and Spanish juniper scrublands: vegetation in these localities is composed mainly of common juniper (Juniperus communis), Spanish juniper (Juniperus Sabina). Cytisus galianoi and Genista baetica are also important species in these ecosystems. These scrublands rarely exceed 60 cm in height and appear intermingled with rocks and stony ground. Transects (n=4) located in this ecosystems comprise an elevational range from 2000 to 2300 m a.s.l. (average: 2150 m a.s.l.). -High-summit ecosystems: composed by typical Alpine landscape. These ecosystems are characterized by rocky outcrops that originated from glacial activity, pastureland, small snow beds, and glacial lagoons. The four transects that represents this Mediterranean high mountain habitat comprise an elevational gradient from 2280 to 3100 m a.s.l., with an average elevation of 2580 m a.s.l.

Sampling

Sampling procedure was the line-transect method (Verner, 1985), with a bandwidth of 50 m, 25 m on each side of the line (Barea-Azcón et al 2012, 2014). A total of 16 transect were sampled with lengths ranged from 1.9 to 3 km. Sight and sound records within the sample area were accepted as contacts. All transects were sampled in the early morning, under appropriate climatic conditions. The observer walks at a constant speed of 2 to 4 km/h. Transects are repeated at least once per month provided that the conditions of snow cover permitting. This implies that the sites located on the higher elevations are sampled only from late spring to early autumn.

Quality Control

The sampling transects were georeferenced using a Garmin eTrex Legend GPS (WGS 84 Datum) with an accuracy of ±5 m. We also used colour digital orthophotographs provided by the Andalusian Cartography Institute and GIS (ArcGIS 9.2; ESRI, Redlands, California, USA) to verify that the geographical coordinates of the transect were correct (Chapman and Wieczorek 2006). For the identification of the specimes several fields guides were used (De Juana and Varela 2000, Jonsson 2001). The scientific names were checked with database of the IOC World Bird List (v 5.52) (Gill and Donkster 2015). We also used the R package taxize (Chamberlain and Szocs 2013, Chamberlain et al. 2014) to verify the taxonomical classification. We also performed validation procedures (Chapman 2005a, 2005b) (geopraphic coordinate format, coordinates within country/provincial boundaries, absence of ASCII anomalous characters in the dataset) with DARWIN_TEST (v3.2) software (Ortega-Maqueda and Pando 2008).

Method steps

1. All data were stored in a normalized database (PostgreSQL) and incorporated into the Information System of Sierra Nevada Global-Change Observatory. Taxonomic and spatial validations were made on this database (see Quality-control description). A custom-made SQL view of the database was performed to gather occurrence data and other variables associated with occurrence data, specifically: • Birds Count: Number of individual recorded by the observer within transect (see Sampling description) • Distance: Distance of the contact (bird) to transect line. The distance is estimated by eye. The occurrence and measurement data were accommodated to fulfill the Darwin Core Standard (Wieczorek et al. 2009, 2012). We used Darwin Core Archive Validator tool (http://tools.gbif.org/dwca-validator/) to check whether the dataset meets Darwin Core specifications. The Integrated Publishing Toolkit (IPT v2.0.5) (Robertson et al. 2014) of the Spanish node of the Global Biodiversity Information Facility (GBIF) (http://www.gbif.es/ipt) was used both to upload the Darwin Core Archive and to fill out the metadata. The Darwin Core elements for the occurrence data included in the dataset are: occurrenceId, modified, language, basisOfRecord, institutionCode, collectionCode, catalogNumber, scientificName, kingdom, phylum, class, order, family, genus, specificEpithet, scientificNameAuthorship, continent, country, countryCode, stateProvince, county, locality, minimumElevationInMeters, maximumElevationInMeters, decimalLongitude, decimalLatitude, coordinateUncertaintyinMeters, geodeticDatum, recordedBy, day, month, year, EventDate. For the measurement data, the Darwin Core elements included were: occurrenceId, measurementID, measurementType, measurementValue, measurementAccuracy, measurementUnit, measurementDeterminedDate, measurementDeterminedBy, measurementMethod.

This dataset includes a total of 27847 records of the order Passeriformes. There are 16 families represented in this dataset. Nearly one third of the specimens belong to the family Fringillidae. A total of 44 genera are represented in this collection, with Emberiza, Cyanistes, Turdus, Fringilla and Parus having the highest number of records (Figure 3). There are 70 taxa of this dataset included in the European Red List (BirdLife International 2015): 67 categorized as Least Concern; 2 Not evaluated, and 1 taxa considered as Vulnerable. According to Spanish Red List (Madroño et al. 2004), 3 taxa of this dataset are considered under Near Threatened category, 1 taxa as Vulnerable and 1 as Least Concern categories respectively

1. Aves
   rank: class
2. Aegithalidae
   rank: family
3. Alaudidae
   rank: family
4. Certhiidae
   rank: family
5. Cinclidae
   rank: family
6. Corvidae
   rank: family
7. Fringillidae
   rank: family
8. Laniidae
   rank: family
9. Motacillidae
   rank: family
10. Muscicapidae
    rank: family
11. Paridae
    rank: family
12. Passeridae
    rank: family
13. Phylloscopidae
    rank: family
14. Sittidae
    rank: family
15. Sturnidae
    rank: family
16. Sylviidae
    rank: family
17. Turdidae
    rank: family
18. Aegithalos
    rank: genus
19. Alauda
    rank: genus
20. Anthus
    rank: genus
21. Carduelis
    rank: genus
22. Certhia
    rank: genus
23. Cinclus
    rank: genus
24. Coccothraustes
    rank: genus
25. Corvus
    rank: genus
26. Cyanistes
    rank: genus
27. Emberiza
    rank: genus
28. Erithacus
    rank: genus
29. Fringilla
    rank: genus
30. Galerida
    rank: genus
31. Garrulus
    rank: genus
32. Hippolais
    rank: genus
33. Lanius
    rank: genus
34. Lophophanes
    rank: genus
35. Loxia
    rank: genus
36. Lullula
    rank: genus
37. Luscinia
    rank: genus
38. Miliaria
    rank: genus
39. Monticola
    rank: genus
40. Motacilla
    rank: genus
41. Muscicapa
    rank: genus
42. Oenanthe
    rank: genus
43. Oriolus
    rank: genus
44. Parus
    rank: genus
45. Passer
    rank: genus
46. Periparus
    rank: genus
47. Petronia
    rank: genus
48. Phoenicurus
    rank: genus
49. Phylloscopus
    rank: genus
50. Pica
    rank: genus
51. Prunella
    rank: genus
52. Pyrrhocorax
    rank: genus
53. Regulus
    rank: genus
54. Saxicola
    rank: genus
55. Serinus
    rank: genus
56. Sitta
    rank: genus
57. Spinus
    rank: genus
58. Sturnus
    rank: genus
59. Sylvia
    rank: genus
60. Troglodytes
    rank: genus
61. Turdus
    rank: genus

Sierra Nevada (Andalusia, SE Spain), is a mountainous region with an altitudinal range between 860 m and 3482 m a.s.l. covering more than 2000 km2 (Figure 1). The climate is Mediterranean, characterized by cold winters and hot summers, with pronounced summer drought (July-August). The annual average temperature decreases in altitude from 12–16°C below 1500 m to 0°C above 3000 m a.s.l., and the annual average precipitation is about 600 mm. Additionally, the complex orography of the mountains causes strong climatic contrasts between the sunny, dry south-facing slopes and the shaded, wetter north-facing slopes. Annual precipitation ranges from less than 250 mm in the lowest parts of the mountain range to more than 700 mm in the summit areas. Winter precipitation is mainly in the form of snow above 2000 m of altitude. This mountain area comprises 27 habitat types from the Habitat Directive. Sierra Nevada protected area contains 72 animal species (44 breeding birds, 17 mammals, 5 invertebrates, 2 amphibians and 4 reptiles) and 20 plant species listed in the Annex II and/or in the Annex IV of Habitat or Bird directives. It is thus considered one of the most important biodiversity hotspots in the Mediterranean region (Blanca 1996, Blanca et al. 1998, Cañadas et al. 2014). Sierra Nevada has several legal protections: Biosphere Reserve MAB Committee UNESCO; Special Area of conservation (Natura 2000 network); Natural Park and National Park. The area includes 61 municipalities with more than 90, 000 inhabitants. The main economic activities are agriculture, tourism, cattle raising, beekeeping, mining, and skiing (Bonet el al. 2010).