The aim of this study was to examine the effects of fire on resource use by a population of koalas in remnant coastal forest. Fifty-five koalas were monitored regularly by radio-tracking for up to 35 months. The attributes of each tree in which the koala was sighted were recorded, giving a total of 8390 records. Analyses were undertaken on a range of ecological information. Regeneration of the forest began immediately following the fires and within three months koalas were seen among the epicormic growth. From a total 4631 trees used by koalas, 3247 (70%) were burnt. Observations of koalas feeding included 53% in burnt trees. Koalas changed trees frequently; individual trees were used once only on 3555 occasions (42% of all observations). Of all the trees used, 95% were used by only one collared koala; no trees were used by more than three koalas. Swamp mahogany (Eucalyptus robusta) was the tree species most frequently used by koalas, particularly at night and by breeding females. Koalas preferred trees of larger diameter (>30 cm) and used significantly taller trees during summer. This study has shown that resource depletion from intense wildfire is short-term for koalas because they utilise burnt trees within months of the fire for both food and shelter.

The Port Stephens Koala Phascolarctos cinereus population has been regarded as one of the strongholds for Koalas in New South Wales. This study applied population viability analysis to investigate the impact of fire and predation by dogs on the viability of the local population. The rapid decline of the modelled Koala population under basic assumptions throws the assumed security of such large populations into question. In all the modelled management scenarios, reducing mortality had more influence than any other factor. Reducing the severity and frequency of large catastrophic fires improved the probability of survival for the population, though the modelled population size still declined sharply. Any management action to improve Koala survival must be accompanied by a reduction in mortality from dog attacks. Fires and dogs will have an ever greater impact on Koala populations as coastal forests become more fragmented and isolated by urban development, and their combined control will be needed to complement land-use planning measures to address habitat loss and fragmentation.

No abstract

The increasing fragmentation of fire-prone forests of Australia has made the remaining populations of koalas (Phascolarctos cinereus) more vulnerable to extinction. We examined the movement patterns of koalas in remnant forest of Port Stephens following a major wildfire. Each koala (n = 55) was monitored regularly by radio-tracking for up to 35 months. The movements of koalas showed a wide variation in patterns, from highly localised movements to long-range dispersal over 20 km. Within the first 12 months, 35% of tracked koalas moved from their release location to new areas where they established home ranges. Daily movement distances of males (mean = 278.3 m) was higher than for females (141.0 m). Monthly displacement ranged from less than 10 m to more than 5 km, and was higher for koalas that subsequently died. Home ranges of males (95% kernel) were significantly larger than those of females (mean for males = 58.9 ± 10.5 ha; mean for females = 25.7 ± 8.6 ha), and this sex difference was also evident for core areas (50% kernel). There were no differences in the movement patterns or home-range sizes of rehabilitated koalas compared with wild koalas. This study has shown that resource depletion from wildfire is short term for koalas because their mobility allows rapid recolonisation of the burnt forest, and they can maintain home ranges within sites regenerating from fire. The reintroduction of rehabilitated koalas into burnt forest may also assist in the recovery of populations in fragmented and isolated habitat.

In Australia, baiting with 1080 (sodium fluoroacetate) is widely used to reduce predation of native wildlife by the red fox. However, such control programs may place some native carnivores at risk, particularly the spotted-tailed quoll in eastern Australia. We measured the mortality in a total of 57 quolls fitted with mortality radio-transmitters during four experimental fox baitings with Foxoff® 1080 baits containing Rhodamine B in north-east New South Wales. In all experiments quolls visited bait stations regularly and removed a total of 20 baits. All but one of these baits was found in the vicinity of the bait station, indicating that quolls did not ingest baits. This was confirmed by the absence of Rhodamine B in the vibrissae of all quolls retrapped after baiting. The only quoll that may have died from a bait had eaten a cached bait some six weeks after baiting concluded. Thus, baiting did not threaten any of the quoll populations sampled. Therefore it appears that most restrictions imposed to protect spotted-tailed quolls during fox baiting are unnecessary as long as this bait type is used.