Trial by fire Survival of the northern bettong January 1999

A problem of balance The northern bettong (Bettongia tropica) Fire has played an important role in shaping Australian ecosystems with The northern bettong (Bettongia tropica) is a small rat-kangaroo (Potoroidae), many native plants and animals weighing in at an average of 1.2kgs. The claws on their forepaws are well adapting to a fire-prone landscape. developed for digging and their tails can be used for carrying nesting material. Little is known however, about the responses of individual species to Their diet consists mainly of sporocarps (truffles) from hypogeous (underground) fungi that they dig from the soil often around the bases of host trees. At least 35 fire. An example of such adaptation different truffle species are on the menu. Truffles are eaten all year round, with is the relationship between fire, grass roots, herbs and lilies supplementing the diet at different times of the year. certain below ground (hypogeous) mycorrhizal fungi and fungi-eating (mycophagous) marsupials. Karl Vernes examined this relationship in his PhD studies.

Many trees in our forests depend on hypogeous fungi for healthy growth. Primarily, hypogeous fungi provide trees with mineral nutrients. They also enhance resistance to disease and the ability to take up water, as well as allowing trees to withstand a greater range of temperature, salinity and pH levels.

Mammals eat the nutritious fruiting bodies of hypogeous fungi which are commonly known as ‘truffles’. When they do so, the spores of the fungus not only pass through the digestive system of the animal unharmed but are more likely to The northern bettong is an endangered species that in recent times is known to germinate as a result of this inhabit just four northeastern Queensland locations. It is found in the Lamb passage. In this way, mycophagous Range, the Mt Windsor Tableland, Mt Spurgeon on the Carbine Tableland and marsupials help to maintain the has recently been found near Paluma. health of our forest ecosystem by The Lamb Range population is the only one considered to be secure although it dispersing mycorrhizal fungal is still limited to an area only 25km long and 6 kms across at its widest point. spores and increasing the likelihood of new individual fungi forming. Objectives of the research Karl used data from trapped Truffles of hypogeous fungi The research was designed to bettongs to estimate numbers and responded to fires as follows: answer two main questions: to record or monitor population 1. How does fire effect the changes, body weight and • they were more available to availability of hypogeous fungi reproduction of his animals. bettongs immediately after the to the bettong? Radio collars were fitted to trapped fire, mainly because they 2. What impact does fire-related animals so their locations could be became easier for the bettongs change in the hypogeous fungi determined at any time from the to detect, and community have on the radio signal. Receivers were set up • several months after the fire, the bettong’s diet, home range and at different points around the study ability of bettongs to detect broad-scale movement within area and compass bearings taken to fungi on the burnt site the environment? the signal from each point. The decreased to very low levels, location where these bearings whereas this increased on the Past studies have indicated that fire intersect gave the locations of the unburnt control sites. Both may initiate changes to fruiting of animals. burnt and control sites had hypogeous fungi. Since these fungi returned to normal levels are an important part of the Responding to fire within 12 months. bettong’s diet such information According to Karl, radio-location could lead to better ways of and trapping data indicated that Conclusions managing bettongs and their most, if not all bettongs experienced In this study bettongs appear habitat. no ill effects from the fire itself. mostly unaffected by fire, and are Bettong responses to the fire event quite flexible in their response to Playing with fire showed: changing rates of truffle detection. In the study area at Davies Creek, This indicates that they may be a experimental fires were conducted • no change in the survival of fire-adapted marsupial, able to over two burning (dry) seasons in bettong pouch-young after the survive well under conditions 1995 and 1996. These fires were of fires, where low to medium intensity fires low to medium intensity and • home range size and location occur frequently. However, further typically only burned the did not change following the studies would need to be conducted understorey grasses and low fires, and animals still moved to see how bettongs adjust to an shrubs. Fires are a difficult tool to around the area as previously, environment where there were manipulate, so experts from the and longer intervals between fires or Departments of Environment and • when faced with a choice of where fires are suppressed Heritage, Natural Resources and burnt or unburnt areas the altogether. CSIRO were recruited to help with bettongs preferred to forage in the burning experiments, along burnt areas. with several volunteers. The animals appeared to be more For further information please Close inspection of the site showed successful in foraging after the fire, contact: that low to medium intensity fires possibly because of the increased at Davies Creek were regular availability of fungi on the burnt Dr Chris Johnson phenomena, occurring about every ground and the decrease in ground- Zoology & Tropical Ecology two to four years. However, there layer vegetation following the burn James Cook University, Townsville did not appear to have been a fire at made travelling easier for this small Ph: (07)47814141 Fax: (07)47251570 most sites for at least three to four animal. Fungus remained the major [email protected] years or longer in some areas. Most part (56%) of the bettongs diet both sites could be considered due for a before and after the fire, throughout fire according to historic fire all seasons. regimes.