Long-term monitoring of lizards and geckos in Doñana 2005-2021

Study Extent

The study area is located in southwest Spain in the Guadalquivir Basin and cover the Natural Area of Doñana (Natural Park with 538,35 km2 and National Park with 542,51 km2). The climate is Mediterranean sub-humid with Atlantic coast influence: wet mild winters and dry warm summers. The rainy period occurs between October and April, with a peak in December–January (yearly average precipitation is about 550 mm). Four main ecosystems are described in the area: the marsh, mobile dunes, Mediterranean shrubland with pine forests and a long beach of 30 kms.

Sampling

The monitoring of the reptile community in Doñana was initiated in 2005 as part of the Monitoring Program of Natural Resources and Processes. The aim was to obtain a temporal and continuous series of data in the abundance of lizards and geckos species and analyze the trends to detect changes in their populations. The records are collected annually between 2005-2021 by members of the monitoring team which perform 7 sampling transects in different habitats (dunes and Mediterranean vegetation) three times per year in the periods when reptile activity is high (March-June and September-October), with good environmental conditions (temperature between 17 and 25 ºC and absence of rain).

Quality Control

The protocol used has been supervised by herpetological researchers and the data have been validated by the members who performed the transects.

Method steps

1. Lizard and gecko counts are collected annually by members of the monitoring team three times per year in the periods when reptile activity is high (two samplings in March-June and one sampling in September-October), with good environmental conditions (temperature between 17 and 25 ºC and absence of rain or strong wind conditions). The method used to record the presence and abundance of lizard and gecko species (kilometric index: number of individuals/km) are the transect censuses. Individuals are visually searched along seven transects (linear or circular) that are carried out by one trained person on foot. Each transect have an established length, but the length surveyed is different (averaged 1858 ± 51.86 meters). Each transect is located in dunes or mediterranean vegetation habitats, representative of Doñana ecosystems. Two transects runs through wooden footpaths (within the Natural Park and five transects are placed on sand-trails (4 within the National Park and one in Natural Park which contains a small part of wooden footpath). Linear transects have been surveyed in the outward track direction and after waiting 15 minutes it has been again performed on the way back. This information is valid to account for species presence in the area. However, we suggest to choose the first survey performed for statistical analyses that require independence of samples.
   Eight species can be potentially observed during the samplings: Mediterranean house gecko (Hemidactylus turcicus), Common Wall Gecko (Tarentola mauritanica), Fringe-fingered Lizard (Acanthodactylus erythrurus), Algerian Psammodromus (Psammodromus algirus), Western Psammodromus (Psammodromus occidentalis), Carbonell's wall lizard (Podarcis carbonelli), Andalusian wall lizard (Podarcis vaucheri), Ocellated lizard (Timon lepidus). Other reptile species present in Doñana have not been included in this study as the detection with this method is very low. For instance, to detect species with a fossorial behaviour (the Mediterranean Worm Lizard Blanus cinereus) or those cryptic as adders (Vipera latastei), it is required larger investment of survey which consist in looking under vegetation, burrows or logs (there are not stones in Doñana). Data recorded during the surveys include weather description (cloud cover, temperature, rain, or wind speed), species identification, number of individuals, sex and life stage of the reptiles when possible, as well as time and georeferenced data of the observation. Between 2005-2007 data was registered in Excel file and since 2008 data is recorded with the app CyberTracker (see protocol). The protocol used has been supervised by herpetological researchers and the data have been validated by the members who performed the transects. Díaz Paniagua, C., & Rivas Carballo, R. 1987. Datos sobre actividad de anfibios y pequeños reptiles de Doñana (Huelva, España). Mediterránea. Serie de Estudios Biológicos, N. 9 (marzo 1987); pp. 15-27. Enciclopedia virtual de los vertebrados españoles. Museo Nacional de Ciencias Naturales. https://www.vertebradosibericos.org. McDiarmid, R. W., Foster, M. S., Guyer, C., Chernoff, N., & Gibbons, J. W. (Eds.). (2012). Reptile biodiversity: standard methods for inventory and monitoring. Univ of California Press. Román, J., Ruiz, G., Delibes, M. & Revilla, E. 2006. Factores ambientales condicionantes de la presencia de la lagartija de Carbonell, Podarcis carbonelli (Pérez–Mellado, 1981) en la comarca de Doñana. Animal Biodiversity and Conservation 29.1: 73-82. Valverde, J.A. 1967. Estructura de una comunidad mediterránea de vertebrados terrestres. Consejo Superior de Investigaciones Científicas Vol. 1. Madrid.

Each individual is identified to the species level whenever possible, otherwise it is recorded as unidentified.

1. Acanthodactylus erythrurus
   common name: Fringe-fingered lizard rank: species
2. Podarcis vaucheri
   common name: Andalusian wall lizard rank: species
3. Podarcis carbonelli
   common name: Carbonell's wall lizard rank: species
4. Timon lepidus
   common name: Ocellated lizard rank: species
5. Psammodromus algirus
   common name: Algerian Psammodromus rank: species
6. Psammodromus occidentalis
   common name: Western Psammodromus rank: species
7. Tarentola mauritanica
   common name: Common Wall Gecko rank: species
8. Hemidactylus turcicus
   common name: Mediterranean house gecko rank: species

The study area covers the Doñana Protected Area. This includes seven ecosystems types (coastal waters, beach, dunes, forest, shrubland, sandy lakes and marshes) and 21 habitat types, 11 of them of high conservation importance – such as the Bulrush and Glasswort marsh, floodplain lakes, sandy lakes, grassland ecotones, Cork-Oak forest, shrubland, coastal Juniper forest and dunes.