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Townsville, Australia

Campbell H.A.,University of Queensland | Dwyer R.G.,University of Queensland | Fitzgibbons S.,University of Queensland | Klein C.J.,University of Queensland | And 6 more authors.
Endangered Species Research

The southern cassowary Casuarius casuarius johnsonii L. is an endangered flightless bird from northern Australia. The cassowaries' rainforest habitat has been extensively cleared, and the population primarily exists within discrete protected areas. They do, however, venture outside the reserves into modified landscapes, and it is here they are exposed to threatening processes. We used GPS-based telemetry and the adaptive local convex hull (a-LoCoH) non-parametric kernel method to define the relationship between cassowary home range (HR) and a protection- area network. The study showed that: (1) females had a larger HR than males; (2) overlapping HR occurred between but not within the sexes; (3) HRs of the same sex partitioned along defined boundaries; and (4) the current protected areas only encompassed core HR for the inhabiting cassowaries. This information was incorporated within a spatial-conservation-prioritisation analysis to define the relative cost:benefit relationship for protecting the currently non-protected land utilised by the cassowaries. The results showed that the current reserve system may accommodate up to 24 adult cassowaries, only offering HR protection at the 40 to 60% a-LoCoH. This could be raised, relatively cheaply (1.2-fold the current costs), to 70% a-LoCoH for all birds by protecting adjacent forested areas on private land. Protection beyond the 70% a-LoCoH, however, required protection of large expanses of agricultural land, resulting in an exponential increase in monetary cost (5.1-fold). We argue that total HR protection for the cassowaries was an unfeasible conservation option, but protection of core habitat was achieved relatively cheaply. Combining core HS protection with target incentives to landowners of adjacent cleared land may be the most costeffective conservation strategy for C.c. johnsonii. © Inter-Research 2012. Source

Stevens N.,South African Council for Scientific and Industrial Research | Stevens N.,University of Cape Town | Swemmer A.M.,South African Environmental Observation Network | Ezzy L.,Queensland Parks and Wildlife | Erasmus B.F.N.,University of Witwatersrand
Journal of Vegetation Science

Questions: Early bioclimatic models predict that climate change in southern African savannas will cause a huge southward and westward range shift of the savanna tree Colophospermum mopane (Kirk ex Benth.) Kirk ex J.Léon. C. mopane is an economically and ecologically important subtropical savanna tree that forms mono-dominant stands across 30% of southern African savannas. We investigate the validity of these initial range expansion predictions to answer the following questions: what are the regional-scale drivers of the distribution of C. mopane in southern African savannas; and what are the landscape-scale distribution patterns of this species? Location: Central Lowveld, Kruger National Park, South Africa. Methods: We investigate the validity of very early range expansion modelling predictions using a regional-scale, climate envelope niche model, and fine-scale field mapping of the current boundary, to understand which environmental variables may determine the distribution limit of this signature species. Results: Our findings indicate that both non-climatic (dry season day length) and climatic (minimum temperatures) variables limit the regional distribution of C. mopane. At the landscape scale, the distribution of this species is restricted to the warmer parts of the landscape, suggesting minimum temperature appears to be the primary factor determining its landscape-scale distribution. Conclusions: This study provides the first detailed model of environmental factors that may limit the regional distribution of C. mopane, and allows us to formulate testable hypotheses regarding the determinants of the range of a keystone species. © 2013 International Association for Vegetation Science. Source

Campbell H.A.,University of Queensland | Sullivan S.,Queensland Parks and Wildlife | Read M.A.,Queensland Parks and Wildlife | Gordos M.A.,Australian Department of Primary Industries and Fisheries | Franklin C.E.,University of Queensland
Functional Ecology

Body mass is a key determinant of diving performance in endotherms. In air-breathing ectotherms however, this paradigm occurs with considerably less force. Here, through remote recordings of dive behaviour over a wide size range (5-42 kg body mass, n = 17) of freshwater crocodiles (Crocodylus johnstoni), we demonstrate why body mass is such a poor determinant of dive duration for ectothermic divers. Crocodiles were released into the wild with a time-depth-recorder attached to their dorsal scutes, and a movement activated radio-tag attached to their tail. Over 15 days, 652·6 ± 58·4 (mean ± SE, n = 17) dives were recorded, with all individuals exhibiting two specific dive-types. These were, a resting-dive (62·7 ± 5·4% of total dive no.), where no activity occurred during the dive, and an active-dive (37·1 ± 6·3% of total no.) associated with swimming. The durations of resting-dives (∼12 min) were similar for all crocodiles. Smaller crocodiles (6·3 ± 0·7 kg, mean ± SE, n = 9) exhibited a significant correlation between dive duration and post-dive surface-interval, whilst larger crocodiles (17·9 ± 3·75 kg, mean ± SE, n = 8) did not. This demonstrated that aerobic dive duration was mass-specific during resting-dives, but other mass specific factors, presumably ecological, determined dive duration. The durations of active-dives were never >1 min, showed no relationship with body mass and no correlation with the post-dive-surface interval. In crocodiles, aerobic metabolic scope is independent of body mass but anaerobic capacity is mass dependent, suggesting that active-dive duration was determined by sustained activity and dives were terminated before anaerobic metabolism became significant. All individuals showed similar diel phase shifts in dive duration, type and depth, illustrating the overwhelming influence of the external environment on dive behaviour. Dive durations which resulted in significant anaerobic debt occurred rarely, but were undertaken in response to a potential threat. Body mass was a poor predictor of diving in C. johnstoni because the external environmental and ecological factors exerted a greater influence on dive duration than oxygen reserves. © 2009 British Ecological Society. Source

Campbell H.,University of New England of Australia | Campbell H.,University of Queensland | Dwyer R.,University of Queensland | Sullivan S.,Queensland Parks and Wildlife | And 2 more authors.
Australian Veterinary Journal

Background: The southern cassowary (Casuarius casuarius johnsonii) attains 1.8m in height and over 80kg in weight. These large birds are equipped with large claws and, although not a direct threat to humans, they have caused serious injury to handlers and members of the public. Methods and results: This study describes chemical immobilisation, restraint, transport and post-monitoring (satellite tracking) methodologies for adult and juvenile southern cassowaries, captured and released from their natural environment. Conclusions: The described methods have improved the management and research opportunities for the southern cassowary and may be transferable to other species of large ratite. © 2014 Australian Veterinary Association. Source

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