Hot climate, hot koalas: the role of weather, behaviour and disease on thermoregulation.

Thermoregulation is critical for endotherms living in hot, dry conditions, and maintaining optimal core body temperature (Tb) in a changing climate is an increasingly challenging task for mammals. Koalas (Phascolarctos cinereus) have evolved physiological and behavioural strategies to maintain homeostasis and regulate their Tb but are thought to be vulnerable to prolonged heat. We investigated how weather, behaviour and disease influence Tb for wild, free-living koalas during summer in north-west New South Wales. We matched Tb with daily behavioural observations in an ageing population where chlamydial disease is prevalent. Each individual koala had similar Tb rhythms (average Tb = 36.4 ± 0.05°C), but male koalas had higher Tb amplitude and more pronounced daily rhythm than females. Disease disrupted the 24-hr circadian pattern of Tb. Koala Tb increased with ambient temperature (Ta). On the hottest day of the study (maximum Ta = 40.8°C), we recorded the highest (Tb = 40.8°C) but also the lowest (Tb = 32.4°C) Tb ever documented for wild koalas, suggesting that they are more heterothermic than previously recognized. This requires individuals to predict days of extreme Ta from overnight and early morning conditions, adjusting Tb regulation accordingly, and it has never been reported before for koalas. The large diel amplitude and low minimum Tb observed suggest that koalas at our study site are energetically and nutritionally compromised, likely due to their age. Behaviour (i.e. tree hugging and drinking water) was not effective in moderating Tb. These results indicate that Ta and koala Tb are strongly interconnected and reinforce the importance of climate projections for predicting the future persistence of koalas throughout their current distribution. Global climate models forecast that dry, hot weather will continue to escalate and drought events will increase in frequency, duration and severity. This is likely to push koalas and other arboreal folivores towards their thermal limit.

Health Assessments of Koalas after Wildfire: A Temporal Comparison of Rehabilitated and Non-Rescued Resident Individuals.

Many koalas (Phascolarctos cinereus) required rehabilitation after the 2019/20 Australian megafires. Little is known about how the post-release health of rehabilitated koalas compares to non-rescued resident koalas. We evaluated health parameters in rehabilitated koalas and resident koalas in burnt and unburnt habitat in southern New South Wales, Australia. Health checks were undertaken within six weeks of fire (rehabilitated group), 5-9 months post-fire and 12-16 months post-fire. Body condition improved significantly over time in rehabilitated koalas, with similar condition between all groups at 12-16 months. Rehabilitated koalas therefore gained body condition at similar rates to koalas who remained and survived in the wild. The prevalence of Chlamydia pecorum was also similar between groups and timepoints, suggesting wildfire and rehabilitation did not exacerbate disease in this population. While there was some variation in measured serum biochemistry and haematology parameters between groups and timepoints, most were within normal reference ranges. Our findings show that koalas were generally healthy at the time of release and when recaptured nine months later. Landscapes in the Monaro region exhibiting a mosaic of burn severity can support koalas, and rehabilitated koala health is not compromised by returning them to burnt habitats 4-6 months post-fire.

Prevalence of cryptococcal antigenemia and nasal colonization in a free-ranging koala population.

Cryptococcosis, caused by environmental fungi in the Cryptococcus neoformans and Cryptococcus gattii species complexes, affects a variety of hosts, including koalas (Phascolarctos cinereus). Cryptococcal antigenemia and nasal colonization are well characterized in captive koalas, but free-ranging populations have not been studied systematically. Free-ranging koalas (181) from the Liverpool Plains region of New South Wales, Australia, were tested for cryptococcal antigenemia (lateral flow immunoassay) and nasal colonization (bird seed agar culture). Results were related to environmental and individual koala characteristics. Eucalypt trees (14) were also randomly tested for the presence of Cryptococcus spp. by bird seed agar culture. In sum, 5.5% (10/181) and 6.6% (12/181) of koalas were positive for antigenemia and nasal colonization, respectively, on at least one occasion. And 64.3% (9/14) of eucalypts were culture-positive for Cryptococcus spp. URA5 restriction fragment length polymorphism analysis identified most isolates as C. gattii VGI, while C. neoformans VNI was only found in one koala and one tree. Colonized koalas were significantly more likely to test positive for antigenemia. No associations between antigenemia or colonization, and external environmental characteristics (the relative abundance of Eucalyptus camaldulensis and season), or individual koala characteristics (body condition, sex, and age), could be established, suggesting that antigenemia and colonization are random outcomes of host-pathogen-environment interactions. The relationship between positive antigenemia status and a relatively high abundance of E. camaldulensis requires further investigation. This study characterizes cryptococcosis in a free-ranging koala population, expands the ecological niche of the C. gattii/C. neoformans species complexes and highlights free-ranging koalas as important sentinels for this disease.

Anaphylactic shock following the bite of a wild Kayan slow loris (Nycticebus kayan): implications for slow loris conservation.

BACKGROUND: Asian slow lorises (Nycticebus spp.) are one of few known venomous mammals, yet until now only one published case report has documented the impact of their venomous bite on humans. We describe the reaction of a patient to the bite of a subadult Nycticebus kayan, which occurred in the Mulu District of Sarawak in 2012. FINDINGS: Within minutes of the bite, the patient experienced paraesthesia in the right side of the jaw, ear and right foot. By 40 minutes, swelling of the face was pronounced. The patient was admitted to Mulu National Park Health Clinic/Klinik Kesihatan Taman Mulu Tarikh, at which time he was experiencing: swollen mouth, chest pain, mild abdominal pain, nausea, numbness of the lips and mouth, shortness of breath, weakness, agitation and the sensation of pressure in the ears due to swelling. The blood pressure was 110/76, the heart ratio was 116 and oxygen saturation was 96%. The patient was treated intramuscularly with adrenaline (0.5 mL), followed by intravenous injection of hydrocortisone (400 mg) and then intravenous fluid therapy of normal saline (500 mg). By 8 h10 the next day, the patient's condition had significantly improved with no nausea, and with blood pressure and pulse rate stable. CONCLUSIONS: A handful of anecdotes further support the real danger that slow loris bites pose to humans. As the illegal pet trade is a major factor in the decline of these threatened species, we hope that by reporting on the danger of handling these animals it may help to reduce their desirability as a pet.

Anaphylactic shock following the bite of a wild Kayan slow loris (Nycticebus kayan): implications for slow loris conservation

Asian slow lorises (Nycticebus spp.) are one of few known venomous mammals, yet until now only one published case report has documented the impact of their venomous bite on humans. We describe the reaction of a patient to the bite of a subadult Nycticebus kayan, which occurred in the Mulu District of Sarawak in 2012.Findings Within minutes of the bite, the patient experienced paraesthesia in the right side of the jaw, ear and right foot. By 40 minutes, swelling of the face was pronounced. The patient was admitted to Mulu National Park Health Clinic/Klinik Kesihatan Taman Mulu Tarikh, at which time he was experiencing: swollen mouth, chest pain, mild abdominal pain, nausea, numbness of the lips and mouth, shortness of breath, weakness, agitation and the sensation of pressure in the ears due to swelling. The blood pressure was 110/76, the heart ratio was 116 and oxygen saturation was 96%. The patient was treated intramuscularly with adrenaline (0.5 mL), followed by intravenous injection of hydrocortisone (400 mg) and then intravenous fluid therapy of normal saline (500 mg). By 8 h10 the next day, the patients condition had significantly improved with no nausea, and with blood pressure and pulse rate stable.Conclusions A handful of anecdotes further support the real danger that slow loris bites pose to humans. As the illegal pet trade is a major factor in the decline of these threatened species, we hope that by reporting on the danger of handling these animals it may help to reduce their desirability as a pet.