Tuning in to the sounds of
endangered black-cockatoos

by Daniella Teixeira

I began my PhD in early 2016 with the idea of testing whether technology that combines biology and acoustics could help monitor the endangered south-eastern red-tailed black-cockatoo, Calytorhynchus banksii graptogyne. Early in my discussions with the recovery team for this subspecies, I realised there were some pertinent questions about its breeding success. The south-eastern red-tail exists in isolation in the far south-west of Victoria and adjacent regions of South Australia. This remoteness makes monitoring with human observers difficult. Volunteers assist with flock monitoring once a year, but direct nest monitoring does not occur. This is where I decided to focus my efforts of using bioacoustics to monitor breeding.

South-eastern red-tailed black-cockatoos are rare and nomadic, and very little is known about their breeding.I was told that finding red-tail nests was going to be very challenging, requiring significant field work. My supervisors quickly suggested that I should perhaps consider investigating another population to ensure I collected sufficient data – this is a PhD after all! That is how I came to include in my research one of the best-studied black-cockatoos – the Kangaroo Island glossy black-cockatoo, Calyptorhynchus lathami halmaturinus. This endangered subspecies has been the focus of enormous conservation efforts for several decades, with several hundred known nests. This was a perfect place to begin to develop some ideas about monitoring breeding.

The conservation situations for these two black-cockatoos are vastly different. Although both subspecies are nationally endangered, the Kangaroo Island glossy black-cockatoo’s population size is increasing while the south-eastern red-tailed black-cockatoo’s is probably decreasing. There are about 400 glossies remaining, and about 1400 red-tails. Both subspecies are extremely specialised in diet, which has undoubtedly contributed to their decline in the face of major habitat alterations. The Kangaroo Island glossy black-cockatoo feeds exclusively on drooping she-oak, Allocasuarina verticillata, and the south-eastern red-tailed black-cockatoo feeds exclusively on stringybark, Eucalyptus arenacea and Eucalyptus baxteri, and buloke, Allocasurina luehmannii. Buloke has been extensively cleared from the red-tails’ range, and it probably contributes little to their diet today.

The glossies on Kangaroo Island have benefitted from intensive management – most importantly, the control the common brush-tail possum which predates on nestlings. An extensive array of artificial nesting hollows has been extremely successful in improving breeding in this population. The red-tails also occasionally use artificial hollows that have been erected, but the recovery team considers that food shortages are its major threat. I’m hoping that by developing a method to directly monitor nesting behaviour, we will be able to examine how differences in food availability across the landscape affect breeding success.

Red-tail nests are difficult to find but, with persistence, I have been able to locate more nests than I have equipment to monitor them. The same is true for the Kangaroo Island glossies, where I have the luxury of being choosy in the nests that I monitor! All going according to plan, there should be more than enough sound data – about eight terabytes in total – to develop bioacoustic methods.

Flock of black cockatoos

I install an autonomous sound recorder at every black-cockatoo nest. They are programmed to record at specific times of the day, depending on the day of the week and the stage of the nest, according to sunrise and sunset times. I’ve been fortunate to work with the excellent sound recorders from Frontier Labs which allow for highly customised programming in the field. The recorders remain at the nests for the duration of nesting, and usually need one or two services for new batteries and SD cards during that time.

I complement these recordings with plenty of behavioural observations at nests. Essentially, this requires me to sit, watch and film nesting birds. I could think of worse ways to spend my days! On a personal level, this field work has been some of the most rewarding work I have done. Being witness to these endangered birds’ nesting behaviours is a privilege, and there’s not a day that I’m not in awe of them. The first time that I observed fledging (when the nestling leaves the nest hollow, which is the time at which we consider breeding to be successful) was one of the major highlights of this project.

I’ve come to be very familiar with the language of these cockatoos at their nests – all the variations of their calls from the adults to the nestling, and even others of their flock. They have a remarkable diversity of call types, although my research focuses on those that I think will be of most benefit to conservation monitoring. Many of the adult calls are useful, but the most valuable calls are those of the nestlings, especially calls in the lead up to fledging and during the event itself. I’ve not determined any calls that are unique to fledging, but there sure is a vocal commotion – a celebration, as I like to think of it. Mum, dad and baby create a cacophony of calls from the moment the nestling decides to take its first flight.

My PhD has been designed to be as practical for conservation managers as possible. That has been crucial in everything I’ve done. This includes testing the sound recorders at the base of the nest trees instead of near the very high nest hollows – no climbing of huge (usually dead) trees required! I’m also trialling an open-source approach to automating the detection of the cockatoos’ calls from the sound recordings. Both these steps are critical for the method to be useful in the real world.

In the next phase of this research, I’d like to test the method on other threatened populations of glossy and red-tailed black-cockatoos. If their vocal behaviours are similar, the method should be transferable. I’ve started this in Queensland, where the glossy black-cockatoo is listed as vulnerable but monitoring does not include any aspect of breeding.

The aim of my PhD is to develop an easy and reliable method to monitor nesting behaviour and success, but the long-term significance of this work is to improve our knowledge of breeding success across the landscape, and the habitat factors that contribute to that. If successful, this will help to inform decisions about where management actions should be focused. I plan on continuing this work beyond my PhD, my hope being to build a community of people who are involved in the monitoring and conservation of black-cockatoos across Australia.

Check out Daniella's website to follow her research.

Media: Dominic Jarvis, dominic.jarvis@uq.edu.au, +61 413 334 924.