Koprowski, J. L. and R. Nandini. 2008. Global hotspots and knowledge gaps for tree and flying squirrels. Current Science 95: 851-856.

Tree and flying squirrels are important components of forested ecosystems, and are advocated as indicators of forest health. In this global assessment of the distribution, endangerment and scientific knowledge of squirrels, we reveal trends that warrant urgent attention. The tropics, particularly the forests of south and southeast Asia, are hotspots of squirrel diversity; however, this region generates the fewest scientific publications on squirrels. Additionally, the most endangered squirrels occur in tropical countries with high deforestation rates, and flying squirrels are more at risk than tree squirrels. Given the combination of high diversity, extinction risk and lack of knowledge of sciurids in the tropics, we recommend increased effort towards understanding their occurrence and biology in the imperiled tropical forests.