Long-term monitoring of the distribution and abundance of diurnal butterflies (Papilionoidea) in Doñana 2007-2022.

The long-term monitoring of Doñana’s diurnal butterflies is part of a harmonised protocol of the Long-term Ecological Monitoring Program of Natural Resources and Processes. The general aim of this protocol is to monitor and assess the dynamics of diurnal butterflies (Papilionoidea) of Doñana (Paz et al., 2014). This group of insects is suitable to include in a monitoring protocol, for several reasons: a relative easy identification, it is a good group as bioindicators due to their short life cycle and their high sensitivity to climate, and their relation with plants allow relate their presence with vegetation changes.

The monitoring of diurnal butterflies (Papilionoidea) in Doñana, southwestern Spain, was initiated in 2005, but until 2007 the protocol is not well stablished, that is why the temporal range of this dataset start in december of 2007 with one transect. From this first transect, in 2008 the Monitoring Program of Natural Resources and Processes applied the BMS methodology to new zones and transects. The principals aims of this protocol were: to inventory all species of diurnal butterflies present in Doñana, in order to detect the appearance of new species or the local extinction of some populations; and know the dynamics and variations of butterflies populations between years and between months, in order to detect declines in these animal populations.

Following the Butterfly Monitoring Scheme (BMS) and Pollard's transects (Sevilleja et al., 2019), the data collection is based in walking transect of a determinate distance where the observer must note, count and identify (when is possible also sex) all butterflies that fly in an imaginary cube of 5 meters of side. The transects are divided into sections with a different or equal length, that usually correspond to different habitat areas. These sections are related to the EUNIS habitat classification (version 2012) and to SACRE habitat classification. In the period 2007-2013, the data was collected with the software CyberTracker and all the butterflys occurences have a coordinate In the period 2007-2013, the data was collected with the software CyberTracker and all the butterflys occurences have a coordinate associated; but since 2014 the data collection was changed to BMS that is why individuals recorded in this period (2014-2022) did not have a coordinate. The transect was adapted to optimal period of butterflies' day activity, that is three or four hours before and after noon, always with suitable climatic conditions: no rain and/or fog, minimum temperature between 13 on sunny days and 17ºC on cloudly days, maximum temperature below 30 ºC and wind conditions under 5 in Beaufort's scale.

In order to know environmental and meteorological variables, temperature, wind conditions (Beaufort's scale) and cloud coverage (eighths of coverage) were measured at initial and final of each transect. The distance of transects varies between 460 and 1170 metres. The time to complete the transects varies depending on the number of individuals observed in each one, but time values are usually between 10 and 75 minutes.