Identifying avian indicators of elevation in the Gondwanan rainforests of Australia

Many montane avian communities are likely to be impacted negatively by future climate change. The ability to monitor these ecosystems effectively is therefore a priority. As species are expected to track their preferred climates by moving upwards in elevation, using indicator species of elevations has been suggested as a climate change monitoring strategy and has been explored for a variety of taxa in eastern Australia. Birds have great potential as vertebrate indicators due to their familiarity, detectability, and well known life histories. We used automated recording units (ARUs) and point counts to sample the avifauna along two elevational gradients in subtropical rainforest in north-eastern New South Wales, Australia. We used the indicator value protocol to identify avian indicators of elevation suitable for long-term monitoring. Pairs of species were more reliable than single species as indicators, and searching for indicators of elevational ranges (e.g. 300–500 m) proved more effective than looking for indicators of single elevations (e.g. 300 m). Point counts and ARUs were equally effective at determining indicators of elevations and ARUs performed particularly well in spring. We present avian indicator sets of lowland and highland sites, which provide a baseline for future monitoring of the effects of climate change on the region’s avifauna. The methodology employed here is broadly suitable for similar studies elsewhere. We propose that the use of ARUs to identify indicator species of elevations is an effective strategy for monitoring the effects of climate change on montane avian communities worldwide.