Tree microhabitats as indicators of cavity using avifauna in tropical forests of India

Documentation and monitoring of biodiversity is major challenge for its effective conservation and management. Tropical forests are ‘cradles of biodiversity’, and monitoring species and communities are even more challenging. Structures such as tree microhabitats are regarded as surrogates of biodiversity. The indicator potential of tree microhabitats have been estimated for the European and Mediterranean regions, and recommended for sustainable management of forests. The indicator potential of tree microhabitats for the tropical regions is not assessed which limits utilization of this tool in tropical regions. Documentation of diversity and abundance of tree microhabitats was carried out in the southern Western Ghats region of India, a biodiversity hotspot. The indicator value was assessed for the cavity-user and non-user avifauna. Tree microhabitats were classified into nine categories and thirty-three subcategories. Indicator potential of each category was estimated using IndVal estimation method. The indicator value of tree microhabitats was also assessed for the presence of tree cavities, a keystone structure. Injuries and exposed wood, epiphytic and epixylic structures, crown deadwood, excrescences and growth forms and Crematogaster ant nests were significant indicator of cavity hosts and cavities. The crown deadwood, growth forms, epiphytic and epixylic structures, fungal fruiting bodies, injuries and exposed wood, and Crematogaster ant nests were significant indicators of avifauna diversity, and for primary and secondary cavity-using birds. Crown deadwood, snags, growth forms buttress, flutes), epiphytes are potential indicators of bird diversity, nesting resources (cavities) and thus integrity of the ecosystem.