EXAMINATION OF DEAD KOALAS
Necropsy examination of free-ranging koalas found dead either incidentally or during field studies and monitoring programs can provide valuable data. When sufficient and representative mortality data can be collected from populations, these data provide critical information on important threats to viability, particularly in declining koala populations.
When coupled with telemetric monitoring of a representative sample of a koala population, such data constitute essential inputs into population viability analyses and can assist in both guiding conservation strategies and adaptively managing existing or emergent threats to population viability.In addition, there are important reasons for diagnosing the cause of death in free-ranging koalas monitored by telemetry.
Fig. 36.4. K-Tracker telemetry collar (Incyt/LX, Sydney, NSW), featuring low-profile and narrow collar material to prevent abrasion and trapping of moisture against the skin, and an integral breakpoint. The breaking strain is controlled by fluorocarbon elastomer o-rings of known break-force (generally 1.5-fold bodyweight). The top-mounted electronic component with integral solar panel delivers GPS and activity data to the internet via field-installed base stations and the lower, weighted module ensures the collar maintains the correct orientation and also contains a standard VHF transmitter.
1. It serves to protect the reputation of the project and project proponents from misinformed criticism that the project (or some aspect of the methods) led to the death of koalas. This can be a significant reputational risk when koala monitoring programs form part of a controversial project, such as a major road development.
2. It permits critical evaluation of the methods used.
It is likely that telemetry device-associated morbidity and mortality are considerably underreported, leading to the persistent use of methods and devices that are not suitable for koalas. Necropsy findings in such cases can guide improvements in device fitting methods and manufacture.Appropriate investigation of deaths of free-ranging koalas, particularly those being studied or monitored, should be considered essential. Necropsy examination should be conducted, whenever possible, by a veterinarian experienced in koala pathology. Some causes of death, such as carpet python constriction, cause very subtle pathological changes, which may be easily overlooked (Robbins et al. 2019). The likelihood of achieving a diagnosis declines rapidly as the time between death and examination increases, so tracking/monitoring frequency of tagged koalas should, whenever possible, be sufficient to detect death and retrieve the carcass within 48 hr. Postmortem decomposition can occur rapidly in warm, humid conditions. Recent advances in telemetry technology allow for near-real-time remote monitoring of koala location and activity levels and facilitate early detection of death and recovery of carcasses (Hanger et al. 2017).
3.