title: Monitoring the effects of climate change on the rainforest birds of eastern Australia
Creators: name: Leach, Elliot
Publisher: name: Griffith University
Year: 2017
Subjects: subject: Climate change
subject: Rainforest birds
subject: Eastern Australia
subject: Avian biodiversity
subject: Ornithology

description: Climate change will significantly affect avian biodiversity on a global scale. Increasing temperatures over the next century will lead to shifts in species distributions, alterations in the timing of breeding and migration, changes in morphology and shifts in genetic frequencies among avian populations. The global hotspots of avian diversity are found in mountainous rainforests, regions which may be difficult to access. Therefore, effective ways of monitoring rainforest bird assemblages are vital, for both ecologists and conservationists. This thesis addresses the challenge of monitoring the effects of climate change on rainforest bird assemblages. I used two methods, point counts and automated acoustic recording, to sample the rainforest birds occupying three elevational gradients in rainforests on the east coast of Australia. In doing so, I had the following aims: 1) to determine whether biodiversity data from automated acoustic recordings made using automated recording units (ARUs) was comparable to data generated using a traditional method (point counts), 2) to assess the ability of ARUs to monitor cryptic rainforest species for long time periods, 3) to identify birds that could be used as indicator species of elevation for the purpose of long-term climate change monitoring, and 4) to investigate the driving factors of bird species richness and abundance along elevational gradients in Australian rainforests. Existing studies showed contrasting results when comparing the effectiveness of traditional avian sampling methodologies with ARUs. To address this in an Australian rainforest context, we collected data on the birds of Eungella National Park in central Queensland over two sampling periods. We found that data from point counts and ARUs was broadly similar. On average, point counts detected more species than recordings of the same duration. The respective strengths and weaknesses of point counts and ARUs are complementary, and they should be used simultaneously in future biodiversity surveys. ARUs can sample remotely, simultaneously, and for long time periods. Using ARUs, we collected a year’s worth of data on two cryptic species inhabiting rainforest in north-eastern New South Wales. Bassian Thrush Zoothera lunulata and Russet-tailed Thrush Z. heinei are secretive inhabitants of wet forests on the eastern coast of Australia. We found that the two species had differential elevational preferences: Bassian Thrush preferred elevations above 900m asl, and Russet-tailed Thrush preferred elevations below 700m asl. Recordings of song indicated that Russet-tailed Thrush bred earlier than Bassian Thrush in 2015. This, along with the elevational preferences of the two species, may be related to temperature. The use of ARUs enabled us to quantify the elevational preferences and likely breeding times of these cryptic species. Populations of Bassian Thrush in north-eastern New South Wales and south-eastern Queensland are likely to decline with increasing temperatures. Upwards shifts in the elevational ranges of rainforest birds are expected due to increasing global temperatures. Identifying the current elevational distributions of indicator species has been suggested as one way of monitoring such upwards shifts. Previous research in our study region had identified indicator species among various invertebrate and plant taxa, but information on vertebrate indicators was lacking. Using data on the elevational preferences of birds collected over one year, we identified avian indicators of lowland and highland rainforest sites in north-eastern New South Wales. These indicators may be used to detect future shifts in species elevational preferences in the region. Previous research in tropical rainforests of the Wet Tropics identified temperature as an important driver of bird species’ distributions. There was a comparative lack of information for the subtropical rainforests of north-eastern New South Wales. Our data from elevational gradients in this region indicated that temperature was significantly positively correlated with both avian species richness and abundance. Species richness declined with elevation; there was no consistent elevational pattern in abundance. We found that species’ functional traits mediated their responses to the changes in environmental conditions along the gradient: large-bodied and small-bodied species are likely to be affected in different ways by increasing temperatures. My research has determined effective ways of monitoring the effects of climate change on rainforest bird assemblages. In doing so, I have also addressed major gaps in the knowledge of two relatively understudied biodiversity hotspots on the eastern coast of Australia. The baseline data presented in this thesis allows future researchers to detect changes in the avian biodiversity of the study regions, and represents a significant contribution to ornithology and climate change research in Australia and internationally.