Reconciling development with conservation of biological diversity has emerged as significant concern in recent years. This has been primarily attempted through establishment of protected areas taken out mainstream development, and through regulating impacts of major development projects with the help of environmental impact assessment exercises. We believe that these two instruments need to be completed by continually providing inputs it the biodiversity implications ongoing development process (and accompanying habitat transformations) at the landscape and regional level .It is desirable that such assessment of biodiversity implications is based on a transparent, objective methodology which could be used by a wide range of practitioners working with the emerging decentralized processes of development planning. In this paper, we outline such a methodology focussing on birds. This involves assessing a conservation value of bird species based on readily available information on their geographical range, habitat preference, endangerment and taxonomic distinctiveness. This may then be translated into a mean composite conservation value for bird assemblages characteristic of different habitat types. By combining this information with that on ongoing processes of habitat transformations, we can provide an assessment of how development processes are affecting biodiversity values.We illustrate this methodology by assessing the conservation value of 586 bird species of Western Ghats and a sample of bird assemblages of seven major habitat types of the region .We conclude that the most serious loss of biodiversity values arises in the transformation of montane shola evergreen forests/high altitude grasslands into monoculture plantations.