Monitoring butterfly abundance along an urbanization gradient: a case study from Kolkata
University Of Calcutta
Quantitative and qualitative reduction of habitats in response to urban development affects native floral and faunal diversity. Depletion of floral habitats corresponds to decrease in butterfly species richness. Monitoring of butterfly species richness has been used as a surrogate for evaluating other biotic diversity. The present study was designed to explore harmonization between flowering rhythm and abundance of butterflies along an urbanization gradient.
The sampling sites were categorized into urban, suburban and rural based on Delphi technique. Survey of butterflies was conducted using Pollard Walk method to identify the relative abundance of butterfly species with respect to number of Lantana camara flowers at each site and spot for one year. Evidences of direct viewing were emphasised and photos were taken in every incident. The data obtained was subjected to ANOVA and multivariate analysis using SPSS and XLSTAT.
Synchronization between the flowering periods with butterflies visiting the plant was apparent in the present study. Results of ANOVA and multivariate analysis revealed that the abundance of butterflies varied significantly with the months and sites. The Pearson correlation and coefficients of determination values varied significantly between the number of flowers, months and abundance of different butterfly species.
The rise of urbanization is interfering with the ecological sanctity of butterflies. The management for butterfly diversity necessarily needs to consider the availability of a range of appropriate nectar resources at different sites, apart from a strict legislation to limit the construction of buildings at the loss of open space and destruction of natural habitats of several important and sensitive species.