Aims
The main purposes of the monitoring of butterflies in Sierra Nevada (BMSSN: Butterfly Monitoring Scheme de Sierra Nevada) are: to record the population trend of the species monitored; to record the phenological patterns of each species and the possible changes that these might undergo with climatic change; to identify environmental variables related to the distribution and abundance of these species; and finally to establish an early-warning system to enable managers of the Sierra Nevada Natural Park and National Park to implement adaptive measures for these species and their ecosystems.
Method and effort
All the butterfly species (except those belonging to the family Hesperiidae) were censused along the transects distributed strategically throughout the work area: oak forests, juniper thickets, thorny shrublands, and summit areas. The methodology consists of walking 10 transects of approximately 2.5 km each between May and September in which all the imagos of the study species (families Papilionidae, Pieridae, Nymphalidae, and Lycaenidae). These walks are made once per week, counting only the specimens sighted 5 m ahead and within a strip of 2.5 m on each side of the observer.
The colonies of species with small and isolated populations require specific effort and monitoring, i.e. elements of great interest for the monitoring of global change that are rarely detected in the preset census transects. In these cases, special effort is dedicated to the mapping of colonies and to the development of models of the ecological niche.
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