Butterfly conservation in the Maltese Islands

Abstract

In recent years, butterfly diversity in the Maltese Islands appears to have fluctuated significantly. While a new species has appeared (accidentally introduced via horticulture) and another (North African migrant) increased in number, others have evidently suffered a considerable decline across their local distribution range. Some argue that this is due to changes in the climatic regime, notably, that an increase in hot and dry weather conditions on the islands has influenced local butterfly populations. Another possible explanation could be related to habitat impoverishment, as a result of land-use changes and increased urbanisation, with the result of increased fragmentation of rural landscapes. Other major threats include an indiscriminate use of pesticides and exploitation of species, particularly for commercial reasons. This study aims to assess the local situation and identify as well as evaluate strategies towards conservation of butterfly species in the Maltese Islands. Butterflies were monitored within nine pre-determined sites; their abundance was assessed by means of transect counts along a route of 300 metres. A vegetation survey was also conducted in all the sites and data concerning the abundance of vegetation was estimated along the same transects. Fifty-five percent of the total number of butterfly species, known to occur in the Maltese Islands, was recorded during the study. The results of the study indicate that valley systems harbour more butterfly individuals than garrigue sites (p<0.05), however, garrigue sites record the highest value for the total number of butterfly species encountered. The study shows a positive correlation (p<0.05) between species richness of butterflies and plants, however, results prove, that, butterfly diversity, does not always depend on the diversity of plant species present along the transect route. Thus, the findings of the present study suggest that butterflies respond not only to adult food resources but are also influenced by the landscape context. An urgent strategy for conserving butterflies in the Maltese Islands is recommended, with a view to address the various issues and problems that are affecting the decline of butterflies. As a first step, a monitoring plan that involves various sites across the islands, should be formulated. In addition, local habitats must be assessed and evaluated to determine whether these merit any special protection in terms of butterfly fauna. Other recommended conservation actions include: identifying food plants and specific habitats for subsequent conservation; raising awareness; promoting butterfly-friendly activities and projects; and providing an effective education scheme. Such a strategy could help thwart imminent extinctions and restore a countryside rich in butterflies.