Please use this identifier to cite or link to this item: https://hdl.handle.net/1959.11/64418
Title: Movements of Rehabilitated and Free-Ranging Koalas (Phascolarctos cinereus) and their Predation Risk, in North-East New South Wales, Australia
Contributor(s): Miller, Amy Lincoln (author); Ballard, Guy  (supervisor)orcid ; Fleming, Peter  (supervisor); Meek, Paul Douglas  (supervisor)
Conferred Date: 2024-10-30
Copyright Date: 2022
Thesis Restriction Date until: 2026-04-30
Handle Link: https://hdl.handle.net/1959.11/64418
Abstract: 

The koala (Phascolarctos cinereus) is one of the world’s most iconic species. It is a national symbol of Australia which influences society, culture and economy. However, in New South Wales (NSW) the koala is endangered, and threats to its survival continue to grow. The future security of koala populations is dependent on understanding and mitigating threats from the cumulative impacts of humans on koala habitat. Although koala management is highly resourced, koala conservation is still constrained by lack of fundamental ecological knowledge. In northeastern NSW I sought to partly address this deficit via research into two key areas: assessing the post-rehabilitation movement status of koalas; and quantifying the risk posed by wild dog predation.

Rehabilitation of sick or injured koalas in wildlife hospitals and shelters is important for the conservation of koalas. The success of koala rehabilitation has normally been measured through treatment, recovery and release into the wild, but comparisons of post-release movement behaviour with those of free-ranging koalas are few. Understanding the fine-scale movement behaviour after rehabilitation-and-release, is key to assessing and improving prerelease care and post-care release strategies.

Domestic dogs (Canis familiaris) attack koalas, and wild dogs (also C. familiaris) have been implicated in the decline of some local koala populations, but in NSW they are not considered a key threatening process. However, to date, little effort has been afforded in understanding the risk of wild dog predation to koalas and having a deeper understanding of the overlap between their fine-scale spatial and temporal movement behaviour will provide greater insight into this potential threat.

I examined the fine-scale spatial and temporal movements of free-ranging and rehabilitated koalas post-release to determine whether the movement behaviours of these two cohorts differed. I then assessed the predation risk wild dogs pose to koalas in a modified peri-urban agricultural landscape in north-eastern NSW, Australia. To quantify the movement patterns, I used fine-scale GPS telemetry on twelve free-ranging and five rehabilitated adult male koalas, three wild dogs, along with detections from an array of 28 camera traps to quantify overlap between the two species in space and time.

Rehabilitation is often employed to support the conservation of koalas, although the true test of its effectiveness is how they respond to reintroduction back into the wild. Rehabilitated koalas appeared to establish activity areas soon after release, and they moved similar distances to free-ranging koalas. Mean distances travelled per movement event (only linear movements greater than 20 metres were included in analyses) were similar between groups (76.8 m and 88.9 m), and mean daily distances travelled were 131 m and 227 m for rehabilitated and free-ranging male koalas respectively. Rehabilitated koalas tended to move only half as frequently as free-ranging koalas, on average just 1.13 movements per day compared to 2.27 per day by free-ranging individuals. Both groups had marked (88%) temporal activity overlap, increasing in activity between dusk and dawn, peaking in activity between 03:00 and 05:00.

I also examined the spatial and temporal movements of rehabilitated and free-ranging koalas to consider the risk of wild dog predation. Koalas and wild dogs had marked (82%) temporal activity overlap, koalas being active between 18:00 and 06:00 and wild dogs between 18:00 and 08:00. Koala activity noticeably peaked just before dawn (03:00 and 05:00), and wild dogs’ peak activity followed closely (06:00). Wild dogs were very active in the study site, detected on 96% of the camera stations within the study site and there is evidence of both species using the same travel pathways to access arboreal habitat, but we observed low spatial coincidence as koalas only made occasional, short (67–69% <100 m) movements with low detection probability.

Considering the endangered status of koalas, understanding all threats is imperative to ensuring the recovery of their population. This study assessed the predation risk wild dogs pose to koalas: the temporal activity overlap of wild dogs and koalas suggested a high hazard of koala predation in this region, but spatial separation suggested a low risk in this region. I found wild dogs and koalas using the same travel pathways, but most koala movements are short, suggesting a short predation risk period. Direct predation was not captured by this study likely due to the short collaring timeframe, however, it has been widely documented in other locations. Therefore, in altered landscapes where both wild dogs and koalas occur and movements on the ground are longer, it may be reasonable to assume wild dogs pose a greater predation risk to koalas, although it may impact an individual, understanding if it impacts upon the broader population is key.

Due to the small sample size, it is unclear why rehabilitated koalas moved half as frequently; it may be due to some koalas being released outside of the breeding season. However, I speculate that some rehabilitated koalas may have a higher risk of predation due to a decreased fitness, therefore, a soft-release program to increase strength and improve climbing and walking ability will likely improve post-release movement and reduce the risk of predation. As a minimum, comprehensive pre-release health checks assessing their strength, climbing ability and general fitness prior to release would be beneficial. Further research on the movement of rehabilitated koalas in relation to the reason for admission, treatment and severity of illness, and time in care compared with release protocols and location is critical to measure post-release survival and what role these animals play in perpetuation of the population.

Publication Type: Thesis Masters Research
Fields of Research (FoR) 2020: 410202 Biosecurity science and invasive species ecology
410206 Landscape ecology
410407 Wildlife and habitat management
Socio-Economic Objective (SEO) 2020: 180602 Control of pests, diseases and exotic species in terrestrial environments
180606 Terrestrial biodiversity
180601 Assessment and management of terrestrial ecosystems
HERDC Category Description: T1 Thesis - Masters Degree by Research
Description: Please contact rune@une.edu.au if you require access to this thesis for the purpose of research or study
Appears in Collections:School of Environmental and Rural Science
Thesis Masters Research

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