Helena Romo

Butterflies in Portuguese ‘montados’: relationships between climate, land use and life-history traits

Butterfly life-history features are expected to co-vary along environmental gradients related to changes in the vegetation structure or composition; however the direction and intensity should vary across regions at the large scale. This study focuses on the butterfly communities of Portuguese ‘montados’. Sixteen sites (mostly cork oak fields) were selected, reflecting a succession gradient in the vegetation of the understorey after human intervention. While controlling for vegetation and broader geographical and climate effects, we looked for trends in butterfly species richness and abundance (using generalised linear models) and for trends in species composition (using redundancy analyses). Moreover, we tried to uncover the co-variation between the butterfly life-history characteristics and succession. The results revealed that butterfly species richness was not significantly influenced by any of the considered variables. In contrast, abundance depended on geographic and oceanity–continentality gradients as it increased towards the East and with more marked temperature annual ranges and less dry summer conditions. Species composition was influenced by temperature ranges and by shrub coverage. There was no strong evidence in favour of fast–slow or generalist–specialist syndromes co-varying along human imposed environmental gradients. However, after controlling for the broad scale variables (geography and climate) shrub cover emerged as a relevant factor. This reinforces the idea that late successional stages are not optimal for butterfly communities. It implies the importance of the extensive methods of traditional management and the negative effects of long-term abandonment.

Ecology and recovery plans for the four Spanish endangered endemic butterfly species

Data compiled during three fieldwork seasons and habitat models provided the tools to produce Species recovery plans for the endangered and endemic butterflies in Spain: Polyommatus violetae, P. golgus, Agriades zullichi, and Euchloe bazae. The distribution of each species has been updated with new field records. For E. bazae and P. violetae the known distribution records increased 33% and 8%, respectively. Detailed habitat descriptions, based on fieldwork data, are given for the four species and models show relatively small and fragmented habitat patches for P. violetae, P. golgus, and P. zullichi. Those areas might be particularly sensitive under a climate change scenario. Habitat of the four species is very specialized and mainly consists of open areas with grassland or scrub vegetation. Population densities are provided for the first time for these species and show low numbers for E. bazae, particularly in the area around Baza in SE Spain. 25 to 54% of the populations were apparently not threatened. For the rest, apparent habitat suitability threats were abandonment for E. bazae and P. violetae, trampling for A. zullichi, and overgrazing for P. golgus. Recovery plans included aspects on legislation, habitat management, precautionary measures (limit new developments and land use changes), research, and public awareness campaigns. Suggested habitat management actions are: (1) support extensive grazing and prevent overgrazing; (2) reduce the effect of trampling by visitors in mountain areas; and (3) woodland and scrub clearing of abandoned areas and pine plantations to improve the quality of grassland habitats.

Relationship between geographic rarity and perception of threat in Iberian butterflies

Measuring threat and selecting ‘flagship’ species for conservation planning should ideally rely on ‘dynamic’ criteria (i.e.: decreasing range and population sizes) which may not be available for most taxa and geographic regions. We address the question of what features of the organisms or of their geographic distributions lie behind selections of potentially threatened species when there is insufficient information on temporal trends. Focusing on Iberian butterflies, we evaluate the support for past and present lists of target species from the most easily quantifiable features of the species’ ranges and conspicuousness (size and visual apparency). Among the features tested, geographic rarity has the highest weight in all the species lists. However, the explanation is rather modest statistically, especially when the species selection is of a supra-regional nature (in this case European). Among the rarest species, those with geographic ranges concentrated in the study area (a) are comparatively few and (b) on average, have less restricted ranges than those whose geographic rarity results from their marginal occurrence in the study area. Finally, the total geographic coverage of the EU-threatened butterflies is relatively large in Iberia. As a consequence species-oriented conservation planning in this region may be rather unrealistic if only geographic rarity is emphasized, or if the levels of threat determined at the supra-regional (European) level are directly translated to the regional legislations. Thus we support the regionally hierarchical approach to conservation proposed by former authors.