Lumholtz’s Tree-Kangaroo: Conserving a rare marsupial May 1999 We know a great deal about the koala fellowship at CSIRO’s Tropical Forest features of the environment were and other cute creatures of Australia, Research Centre in Atherton, Queens- required. This information would assist but tree-kangaroos are elusive animals land. His study focussed on Lumholtz’s in identifying high-quality forest areas that keep well hidden in the rainforest Tree-kangaroo (Dendrolagus lumholtzi), for their future conservation, and be canopy and have maintained a degree one of only two species of tree-kangaroo incorporated into local tree-planting of mystique. Tree-kangaroos are rare in Australia. Found only in the tropical schemes to accommodate more tree- where they exist in the tropical rainfor- rainforests and adjacent forest commu- kangaroos in the future. ests of Australia and New Guinea, nities of North Queensland, Lumholtz’s relying on the fragile and swiftly Tree-kangaroo lives in rugged and Playing hide and seek diminishing tropical rainforest environ- inaccessible rainforest areas including ment for their survival. As land contin- within forest remnants on the Atherton The study site chosen was well-known ues to be cleared for crops and grazing, Tableland. These isolated forest blocks to locals for its population of tree- it is important to understand their provide an important setting to study kangaroos. The 20-hectare block of ecology so we can conserve these rare how these rare animals survive in a mixed remnant/regrowth forest was on arboreal marsupials. How does the tree- fragmented landscape. private land near Yungaburra on the kangaroo respond and adjust to Tablelands, about 70 kilometres inland changes in its environment, such as Objectives of the research from Cairns and 760 metres above sea land clearing, and which specific level. Tree-kangaroos may be easily dangers pose the greatest threat to its Graeme wanted to find out: how the stressed by capture, and to reduce the survival? resident animals used their habitat; chance of this, the animals were anaes- whether they moved regularly to other thetised while radio collars were fitted. Graeme Newell began his search for fragments nearby; which tree species Darting the animals proved successful answers during a post-doctoral they preferred to use and which other and soon Graeme was collecting data on between seven and ten animals at any one time, using a hand held Left: Graeme Newell radio-tracks an adult antenna and telemetry receiver. He male tree-kangaroo (photo Peter Trott) recorded time of day, position in the Right: Graeme fitting a radio-collar to an forest and the species of trees and vines anaesthetised tree-kangaroo. Animals each animal was recover within two hours and are released at the same site they were captured (photo Graeme Newell) Below: Loss of habitat from land clearing represents one of the greatest threats to the tree-kangaroo’s survival (photo Peter Trott) associated with. This enabled him to plants rather than their standard fare of conducted on the animals at this establish how much space the animals leaves from rainforest trees and vines. fragmented study site which show used, how the animals interacted with Overall, it became obvious that the female tree-kangaroos are all each other and which tree species the Lumholtz’s Tree-kangaroos were very related to either of two original animals used regularly. reluctant to leave their homes, except ‘founder’ female tree-kangaroos. perhaps for young male animals yet to Graeme found that even with radio- establish a permanent home range. Issues for conservation signals identifying the presence of a tree-kangaroo in the tree canopy, they A clearer picture emerges Three important issues stand out in often remained invisible, sometimes in species conservation: quite sparse foliage - a very clear in- The study found that Lumholtz’s Tree- dication of just how cryptic they can be. kangaroo: Road deaths are frequent in some areas _ shows an apparent preference for as the animals move between forest Responding to a changing trees such as Black Bean or areas, accounting for the loss of up to a environment Moreton Bay Chestnut, Candlenut, dozen animals per annum - a significant Grey Bollywood and Milky Pine, number when viewed in terms of their After several months the study took a and the spiny vine known as apparent low rate of reproduction, in dramatic turn when the landowner Cockspur Thorn; addition to loss from other causes. informed Graeme he would be clearing _ uses small home ranges within the half the forest block for grazing. While forest fragments - females generally Increased control of predators such as the results were likely to be distressing maintain exclusive and non- dingoes and dogs may be necessary in for both the tree-kangaroos and the overlapping ranges of around 0.7 areas adjacent to tree-kangaroo habitats, researcher, this provided a unique hectares, while males roamed over especially when these habitats are near opportunity to observe how arboreal an average of 1.8 hectares, which residential areas. animals responded directly to loss of could overlap several female and their habitat. It seemed logical land male ranges; Relatively small plots of rainforest on clearing would force these tree-dwell- _ become vulnerable to predation, freehold land, unallocated State Land ing, shy animals to seek out new home loss of condition and starvation, as and land controlled by Local Shire ranges. The results were surprising. well as other causes of fatality, once Councils or other government bodies clearing occurs; may provide important habitat for tree- Five male and six female collared tree- _are highly territorial animals that kangaroos. kangaroos whose ranges fell within the are reluctant to abandon their home 10 cleared hectares did not move away ranges following a severe distur- A more effective strategy in promoting from the area. Instead they continued to bance. This may suggest that tree-kangaroo populations may be the use their original home range despite relocating tree-kangaroos into revegetation of suitable areas not viable the area having been flattened by the forest blocks with existing tree- for agriculture, providing corridors bulldozer. While the tangle of fallen kangaroos could lead to conflict between strategic blocks of preserved trees provided somewhere to live and between the animals, but this forest fragments. protection for some from predators, requires further investigation; others quickly fell prey to dingoes and _ mostly live a sedentary life. Males For further information: dogs. occasionally move between forest Dr Graeme Newell, Arthur Rylah blocks, possibly following antago- Institute for Environmental Research, Those that escaped predation had other nistic encounters with other males, DNRE, 123 Brown Street, Heidelberg, dangers to contend with, such as a but females rarely move from their Victoria, 3084. Phone: (03) 9450 8600, diminished food supply, and would home patch. This has been rein- email: [email protected] likely need to eat potentially toxic forced by recent genetic test results