Winter bird censuses in pine processionary moth (Thaumetopoea pityocampa) monitoring plots

Study Extent

The plots are selected in all types of pine woodlands in the southeast of the Iberian Peninsula. A 500 m long itinerary is established on each plot. Each plot is geolocated with the coordinates and altitude of the midpoint of the itinerary, unless the itinerary is curved, in which case the approximate midpoint of the sampling area is indicated. The censuses are carried out from November 1 to February 28, although in some high mountain plots the census can be carried out until March 15. Whenever possible, six censuses are carried out per plot per winter, uniformly distributed throughout the season.

Sampling

The censuses began in 2019, and the aim is to maintain the census scheme for at least six consecutive winters (till 2025). The census method used is the variable-distance line transect (Gibbons et al. 1996). A 500 m itinerary is walked at a speed of about 2 km/h (about 15 minutes per transect), in the first 4 hours of the day, avoiding rain, snow and wind greater than 4 m/s. All contact with birds is recorded (visual or hearing), noting the bird species, the number of birds per contact, and the perpendicular distance (estimated by eye) between the contact and the census track. All censuses are carried out by the same observer (José Antonio Hódar Correa).

Quality Control

1. The observer periodically trains its skills in bird recognition, whenever possible some helpers take part during censuses in order to test the skill capacity of the observer. 2. Records are stored in an Excel datasheet which is daily updated during the censusing period. 3. Once per year, data are updated to the main database. 4. Storage: data is stored in Linaria (https://linaria.obsnev.es/), the institutional data repository of the Sierra Nevada Global-Change Observatory. Linaria is a normalised database focused on ecology and biodiversity related-data and it is developed in a PostgreSQL/PostGIS relational database management system (RDBMS). 5. Taxonomic validation: scientific names were reviewed by experts and were checked with the GBIF backbone taxonomy using the species matching tool (https://www.gbif.org/tools/species-lookup). 6. Standardisation: the standardisation to Darwin Core was done according to the practices recommended by the TDWG guidelines (https://dwc.tdwg.org/terms/).

Method steps

1. 1. Field sampling (see Sampling Description section). 2. Data is stored in Linaria (https://linaria.obsnev.es/), the institutional data repository of the Sierra Nevada Global-Change Observatory. 3. The dataset was standardised to the Darwin Core structure (De Pooter et al., 2017) as occurrence data. It contains, specifically: 5,886 occurrences, and 5,518 records of associated measurements of the variable: “Distance of the contact (bird) to transect line”. The Darwin Core elements included in the Occurrence Core are: occurrenceID, eventID, catalogNumber, datasetName, collectionCode, institutionCode, ownerInstitutionCode, modified, language, license, eventDate, year, month, day, basisOfRecord, recordedBy, recordedByID, individualCount, scientificName, taxonRank, kingdom, phylum, class, order, family, genus, specificEpithet, scientificNameAuthorship, occurrenceStatus, locality, continent, country, countryCode, minimumElevationInMeters, maximumElevationInMeters, samplingProtocol, decimalLatitude, decimalLongitude, geodeticDatum, coordinateUncertaintyInMeters, habitat. For the Measurement or Fact Extension file, the Darwin Core elements included are: measurementID, occurrenceID, measurementType, measurementValue, measurementUnit, measurementMethod. 4. The resulting dataset was published through the Integrated Publishing Toolkit of the Spanish node of the Global Biodiversity Information Facility (GBIF) (http://ipt.gbif.es).

This dataset includes a total of 5,886 occurrence records (exceeding 8,900 individuals) of the Accipitriformes, Passeriformes, Galliformes, Cuculiformes, Columbiformes, Piciformes, Falconiformes and Falconiformes orders. There are 27 families, 53 genera and 69 species represented in this dataset.

1. Accipitriformes
   rank: order
2. Passeriformes
   rank: order
3. Galliformes
   rank: order
4. Cuculiformes
   rank: order
5. Columbiformes
   rank: order
6. Piciformes
   rank: order
7. Falconiformes
   rank: order
8. Bucerotiformes
   rank: order

All the plots are located in the southeast of the Iberian Peninsula, mostly in the Granada province. There are some preselected plots in the province of Almería, but no censuses carried out so far. The plots were chosen trying to cover as much as possible the diversity of pine woodlands in which the pine processionary moth is present. The altitudinal range covers from sea level to 2500 m altitude, from coastal areas to high mountains and inland depressions, and pine forests can be natural, spontaneous regeneration, or the result of plantations.