Long-term monitoring of the relative density in the Eurasian otter (Lutra lutra) with track counts in Do?ana National Park 2007-2022

The long-term monitoring of carnivore tracks in Do?ana is part of a harmonised protocol for the Long-term Ecological Monitoring Program of Natural Resources and Processes targeting mammals' populations. The general aim of this protocol is to study the temporal evolution of the relative density of the main species of carnivores in the main habitats of the Do?ana National Park. Tracks surveys were done annually after the first rains of the hydrological year, i.e. the first autumn rains, usually in October. Due to climate change, in recent years the rainy season has been delayed until the beginning of the year. This protocol has stablished in 2007 and it has done annually until the present (2022), except in 2021 when due to logistical problems no census was made. Censuses are carried out through 12 prefixed transects, with sand substrate, in Do?ana National Park. Each transect consists of a 2 km of length and 1.5 m of width that is done by a car at a constant speed between 10 and 15 km/h. Transects are cleaned the day before of the census with a metal beam to facilitate the read of the tracks and to ensure that the foot prints were from the previous day. Each transect is repeated in three consecutive days, and during the transect the sand is cleaned for the next day. In the census an expert in mammals? tracks identifies all the tracks, i.e. groups of carnivore foot prints, and he/she records them in Cybertracker. That way, tracks' information like coordinates, hour, species identification and observation was recorded; and also the information of each transect was recorded: surveyors, drivers, date, start and end (hour and coordinates). This method enables to calculate Kilometric Abundance Indexes (KAI) for each species and transect. In order to clarify all carnivore datasets, the data was separated by species, this allows concrete analysis by species. In this dataset Eurasian otter?s (Lutra lutra) data is presented.