Decline causes of Koalas in South East Queensland, Australia: a 17-year retrospective study of mortality and morbidity

González-Astudillo, Viviana; Allavena, Rachel; McKinnon, A.; Larkin, Rebecca; Henning, Joerg

doi:10.1038/srep42587

Cited by 103 publications

(150 citation statements)

References 36 publications

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“…Incidental sampling procedures, such as the use of veterinary hospital records of sick and injured koalas (e.g. Gonzalez‐Astudillo, Allavena, McKinnon, Larkin, & Henning, ), may lead to substantial bias in the estimation of the relative importance of different threats. Predation rates are particularly difficult to quantify without intensive monitoring as predation often occurs in places unfrequented by people and the carcass may be undetectable following consumption or burial.…”

Section: Discussionmentioning

confidence: 99%

Management of multiple threats achieves meaningful koala conservation outcomes

Beyer

Villiers

Loader

et al. 2018

Journal of Applied Ecology

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Management actions designed to mitigate development or anthropogenic impacts on species of conservation concern are often implemented without quantifying the benefit to the species. It is often unclear what combinations and intensities of management actions are required to achieve meaningful conservation outcomes. We investigate whether disease and predator control can reverse population declines of koalas (Phascolarctos cinereus). Based on longitudinal monitoring of the epidemiological and demographic status of over 500 animals over 4 years, coupled with an intensive disease and predator management programme, we use survival analyses to estimate annual age‐specific survival rates and population growth, and simulations to quantify the benefit of these actions. Predation and disease accounted for 63% and 29% of mortality, respectively, across all years, with wild dog (dingoes or dingo‐hybrids: Canis dingo, C. dingo × Canis familiaris), carpet pythons (Morelia spilota) and domestic dogs (C. familiaris) accounting for 82%, 14% and 4% of confirmed predation mortalities, respectively. In the first 2 years, before disease and dog control had major impact, the population was declining rapidly with annual growth rates of 0.66 and 0.90. In the third and fourth years, after interventions had been fully implemented, the population growth rate had increased to 1.08 and 1.20. The intrinsic survival rate of joeys was 71.2% (excluding deaths resulting from the death of the mother). Adult survival rates varied as a function of sex, age and year. Even in a declining koala population, management actions can achieve meaningful conservation outcomes (population growth rates greater than one). However, benefits may be short‐lived in the absence of longer term strategies to manage threats. This work also identifies wild dogs as a major threat to koalas, highlighting the need to better understand how wild dog impacts vary in space and time. Policy implications. Offsetting policy that addresses habitat loss alone may achieve little or no meaningful benefit to declining koalas populations. Management must address suites of threats affecting these populations and ensure that the cumulative effects of these actions achieve positive population growth rates.

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Section: Discussionmentioning

confidence: 99%

Management of multiple threats achieves meaningful koala conservation outcomes

Beyer

Villiers

Loader

et al. 2018

Journal of Applied Ecology

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“…As outlined in a study of koalas living in Queensland (QLD), Australia, the biggest threats affecting populations of this species derive from human population growth and global climate change [8]. Due to the removal of suitable habitat by tree clearing to cater for a growing human population, there are a high proportion of koalas who present to clinical care with injuries consistent with motor vehicle trauma and trauma stemming from animal attacks[9]. Between 1997 and 2013 in SE QLD, 15.5% of koalas admitted into clinical care were diagnosed with motor vehicle trauma, and 5.2% of koalas admitted into clinical care were diagnosed with trauma stemming from animal attacks[9].…”

Section: Introductionmentioning

confidence: 99%

“…Due to the removal of suitable habitat by tree clearing to cater for a growing human population, there are a high proportion of koalas who present to clinical care with injuries consistent with motor vehicle trauma and trauma stemming from animal attacks[9]. Between 1997 and 2013 in SE QLD, 15.5% of koalas admitted into clinical care were diagnosed with motor vehicle trauma, and 5.2% of koalas admitted into clinical care were diagnosed with trauma stemming from animal attacks[9]. Of particular concern is that these koalas had no symptoms of underlying disease, suggesting potential for impact on local population growth by healthy, breeding koalas being prematurely removed[9].…”

Section: Introductionmentioning

confidence: 99%

A 29-year retrospective analysis of koala rescues in New South Wales, Australia

Charalambous

Narayan

2020

Preprint

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The koala (Phascolactos cinereus) is currently listed by both the IUCN and the Australian Governments’ Threatened Species Scientific Committee as vulnerable to extinction with a decreasing population trend. This listing can be attributed to climate change and its impact on ecosystems, and anthropomorphic environmental change due to extensive land clearing and habitat fragmentation. These have both been proven to induce stress, which influences the onset of disease. This novel study performed a retrospective analysis whereby records for 12,543 wild, rescued koalas in New South Wales (NSW), Australia were studied in order to determine trends in koala sightings, clinical admissions and injury diagnoses over a period of 29 years (1989-2018). Results indicated that between all three study locations (Port Stephens, Port Macquarie and Lismore), the most common reason koalas were admitted into care was because of disease, the most common disease diagnosed was signs of chlamydia, and the most common outcome for koalas admitted into care was released. At Port Stephens, mature and female koalas were diagnosed with a disease more than any other age or sex, while juvenile and male koalas were released (back into the wild) more than any other age or sex. Additionally, there were fewer koalas with a disease and fewer koalas released in Port Stephens as each year progressed. At Port Macquarie, mature and male koalas were diagnosed with a disease more than any other age or sex, while juvenile and female koalas were released more than any other age or sex. Additionally, there were more koalas with a disease and fewer koalas released in Port Macquarie as each year progressed. At Lismore, adult and female koalas were diagnosed with a disease more than any other age or sex, while joey and male koalas were released more than any other age or sex. Additionally, there were more koalas with a disease and fewer koalas released in Lismore as each year progressed. Determining trends in clinical admissions and diagnosis over such a substantial period of time is an important factor in preventing the continuing decline of koalas throughout Australia, and in particular NSW. It is important to note that there are cultural differences between koala rescue groups in the three study locations (Port Stephens, Port Macquarie and Lismore). These differences may be reflected in the outcomes of koala patients as each group are driven by their own management team. It is essential that any further decline of koala populations is prevented, however this can only be achieved through informed recommendations through research studies such as these. These recommendations should lead to government legislation which can provide stronger protection to koala habitat.

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“…Threats to this vulnerable species include habitat loss and fragmentation, drought, dog and vehicle interactions, and disease associated with the bacterium Chlamydia (McAlpine et al, 2015). Of all these threatening processes, chlamydial disease has been singled out as the number one aetiology in hospital admissions (Gonzalez-Astudillo, Allavena, McKinnon, Larkin, & Henning, 2017) and a critical threat that, if adequately addressed, could reverse population decline (Beyer et al, 2018;Rhodes et al, 2011).…”

mentioning

confidence: 99%

Developing noninvasive methodologies to assess koala population health through detecting Chlamydia from scats

Cristescu

Miller

Schultz

et al. 2019

Molecular Ecology Resources

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Wildlife diseases are a recognized driver of global biodiversity loss, have substantial economic impacts, and are increasingly becoming a threat to human health. Disease surveillance is critical but remains difficult in the wild due to the substantial costs and potential biases associated with most disease detection methods. Noninvasive scat surveys have been proposed as a health monitoring methodology to overcome some of these limitations. Here, we use the known threat of Chlamydia disease to the iconic, yet vulnerable, koala Phascolarctos cinereus to compare three methods for Chlamydia detection in scats: multiplex quantitative PCR, next generation sequencing, and a detection dog specifically trained on scats from Chlamydia‐infected koalas. All three methods demonstrated 100% specificity, while sensitivity was variable. Of particular interest is the variable sensitivity of these diagnostic tests to detect sick individuals (i.e., not only infection as confirmed by Chlamydia‐positive swabs, but with observable clinical signs of the disease); for koalas with urogenital tract disease signs, sensitivity was 78% with quantitative PCR, 50% with next generation genotyping and 100% with the detection dog method. This may be due to molecular methods having to rely on high‐quality DNA whereas the dog most likely detects volatile organic compounds. The most appropriate diagnostic test will vary with disease prevalence and the specific aims of disease surveillance. Acknowledging that detection dogs might not be easily accessible to all, the future development of affordable and portable “artificial noses” to detect diseases from scats in the field might enable cost‐effective, rapid and large‐scale disease surveillance.

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Decline causes of Koalas in South East Queensland, Australia: a 17-year retrospective study of mortality and morbidity

Cited by 103 publications

References 36 publications

Management of multiple threats achieves meaningful koala conservation outcomes

Management of multiple threats achieves meaningful koala conservation outcomes

A 29-year retrospective analysis of koala rescues in New South Wales, Australia

Developing noninvasive methodologies to assess koala population health through detecting Chlamydia from scats

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