How many butterflies are there in a city of circa half a million people?

Abstract

Urbanization poses severe threats to biodiversity; thus, there is an urge to understand urban areas and their biological, physical, and social components if we aim to integrate sustainable practices as part of their processes. Among urban wildlife groups, butterflies have been used as biological indicators due to their high sensitivity to environmental changes. In this study, we estimated the number of butterflies that live within a neotropical medium-sized city (Xalapa, Veracruz, Mexico) using a robust interpolation procedure (ordinary kriging). Our calculations added an average of 1,077,537 (± SE 172) butterfly individuals that dwelt in Xalapa in the surveyed space and time. The interpolation procedures showed to be robust and reliable, and up to some extent conservative. Thus, our results suggest that there are at least 1.8 butterfly individuals per capita in Xalapa. Notably, higher butterfly abundances tended to be recorded near highly vegetated areas and along city borders. Besides providing the basis for further ecological studies, our results will contribute to the crucial need of scientific data that is lacking, but critically important, for adequate urban management and planning, as well as environmental education.