Butterfly diversity in a regional urbanization mosaic in two Mexican cities

• Within two urban areas butterfly species richness was higher than that of nearby forest ecosystems.
• The highest number of species was found in areas of ecological protection in the two cities.
• The butterflies in these areas reveal a dynamic process which involves many of the species from the nearby forests, along with others.

Latin America is one of the most urbanized developing regions, however little is known about the biodiversity of its cities and the way this biodiversity is affected by landscape and local variables. We evaluated butterfly diversity in two Mexican cities by establishing four categories of urbanization: urban, suburban, areas of ecological protection (AEP) and forest. Butterflies were sampled at 300 m length and 10 m wide transects; rooted-fruit baited traps; and intentional sampling. Species accumulation curves indicate that sampling completeness was 91%; fifty species were recorded, with Satyrinae: Satyrini the richest group (15 species), and Heliconiinae the poorest subfamily (8 species). The AEP and forests had the highest (38 species) and lowest (21 species) richness respectively. Diversity and evenness were low in the most urbanized environments, indicating that urban butterfly ensembles are dominated by few abundant species. As expected, species turnover was greatest between forests and the urban area (Whittaker's species turnover = 50.88). Local variables accounted for 74.9% of the variance in the abundance data, with mean environmental temperature, relative humidity, the number of pedestrians and plant cover the most important variables. At the level of the landscape, at small scale (50 and 100 m) arboreal vegetation cover (%VA) was the most important variable, meanwhile, as the scale increased the variables related to urbanization such as construction cover, number of pedestrian and distance to the center of the city became increasingly important. Connecting forest patches near cities with ecological protected areas would have a positive impact on butterfly diversity.