Bioacoustic monitoring of breeding behaviour in the endangered Kangaroo Island glossy black-cockatoo, Calyptorhynchus lathami halmaturinus, and south-eastern red-tailed black-cockatoo, Calyptorhynchus banksii graptogyne

Abstract

n n n nThis thesis investigates the use of bioacoustic technology for monitoring breedingbehaviours in two endangered subspecies of black-cockatoo, the Kangaroo Island glossyblack-cockatoo, Calyptorhynchus lathami halmaturinus, and the south-eastern red-tailedblack-cockatoo, C. banksii graptogyne. Over three years, I collected breeding behaviouraldata, including animal sound data and video footage, at nests of glossy black-cockatoos onKangaroo Island in South Australia and red-tailed black-cockatoos in the Casterton region ofVictoria. This thesis comprises an introduction (Chapter 1) and synthesis and conclusion(Chapter 6) and four research chapters (Chapters 2 to 5).n n n nIn Chapter 2, I provide a literature review of the potential use of bioacoustics inmonitoring animal behaviour for conservation. I argue that bioacoustic studies should betterincorporate knowledge of speciesr vocal behaviours, to improve the resolution of context-specific data. Animal behaviour is often relevant to conservation, and bioacoustics couldgreatly improve our ability to acquire behavioural data. A necessary first step is to understandthe vocal behaviours of a species to the extent required for conservation monitoring. To thisend, in Chapter 3, I describe the nest-associated vocal behaviours of the Kangaroo Islandglossy black-cockatoo and the south-eastern red-tailed black-cockatoo. Over two breedingseasons, I recorded daily vocal activity at nests using autonomous sound recorders. Combinedwith behavioural observations, including video footage, I identified vocalisations from sixbehavioural contexts: birds in flight, while perched, during begging (adult females), duringcourtship displays (adult males), when entering or sitting near to the nest hollow entrance(adult females), and from nestlings. In total, I describe 14 putative call types for the glossyblack-cockatoo and 11 putative call types for the red-tailed black-cockatoo. For bothsubspecies, the female nest call and nestling calls are the most conspicuous vocal indicatorsof active nesting.n n n nIn Chapter 4, I investigate the utility of bioacoustics for monitoring nest outcomes in theKangaroo Island glossy black-cockatoo and the south-eastern red-tailed black-cockatoo. First,I provide the vocal signal of a successful fledging event for both subspecies. This uniquebehaviour is clearly indicated in spectrograms and provides a bioacoustic signal with whichto confirm nest outcome. I then investigated automated methods to identify nest success orfailure using an open-source call recogniser implemented in the monitoR package in Rsoftware. Constructed from templates of nestling calls, the recogniser was tested on 3 x 3-hours of sound data from early, mid and late stages of the recording period for each nestmonitored (n = 23 for the glossy black-cockatoo; n = 21 for the red-tailed black-cockatoo).Daily nest activity was correctly assigned in 61.9% of survey days analysed for the red-tailedblack-cockatoo, and 68.1% of survey days for the glossy black-cockatoo. Importantly, therecogniser successfully detected the fledging event in almost all cases (five out of sixfledging events in the glossy black-cockatoo, and two out of three fledging events in the red-tailed black-cockatoo). Precision of individual detections was moderate, with many falsepositives. Manual verification of outputs was required, making this a semi-automatedmethod.n n n nIn Chapter 5, I examine the ontogeny of vocalisations in nestlings of the Kangaroo Islandglossy black-cockatoo and the south-eastern red-tailed black-cockatoo. To determine whethernests can be aged from sound recordings, I examined changes in acoustic structure and dailycall rate during nest development. I determined that nestlings vocalised from about 4 weeksof age, but calls were soft and infrequent until about 6 weeks. Daily call rate increased overtime, especially in the final week of nesting. Peak amplitude and low frequency of nestlingcalls increased significantly with development. Call duration increased significantly for theglossy black-cockatoo, but not for the red-tailed black-cockatoo. Average entropy declinedsignificantly for both subspecies. Aggregate entropy declined significantly for the red-tailedblack-cockatoo but not the glossy black-cockatoo. Together, these changes in call rate andacoustic structure provide a useful way to broadly categorise nest age from sound recordingsand thereby improve knowledge on nestling survival. This knowledge may be useful in futurestudies examining the influence of habitat variables, such as food availability, on nestdevelopment and nestling survival across landscapes.n n n nThis thesis presents novel bioacoustic methods for monitoring breeding in the KangarooIsland glossy black-cockatoo and the south-eastern red-tailed black-cockatoo. I demonstratethat these subspecies exhibit diverse repertoires at nests. I describe the vocal signal offledging, which is a direct measure of breeding success, and provide an open-source callrecogniser to aid sound data processing. Finally, I describe the ontogenetic development ofnestling vocalisations. I conclude that bioacoustics has potential to greatly improve nestmonitoring of the endangered Kangaroo Island glossy black-cockatoo and the south-easternred-tailed black-cockatoo, to the benefit of conservation.