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Arid Recovery Restoring Australia’s Arid Lands Feral Facts A resource for land owners Arid Recovery The Landholder’s Pack Australia’s arid zone has suffered the country’s highest extinction rate, particularly for small mammals. Competition with rabbits and domestic stock, and increased predation from introduced predators such as feral cats and foxes have largely contributed to this decline. The purpose of this pack is to share with landholders throughout Australia, but particularly in the arid interior, the findings of various research projects undertaken at Arid Recovery with the aim to: • promote best practice and tested methods • increase efficiency and cost-effectiveness of land management practices • improve communication throughout the arid interior of Australia • offer assistance, support and recommendations Arid Recovery is a unique ecosystem restoration initiative located near the township of Roxby Downs in northern South Australia. Arid Recovery is based around one of Australia’s largest fenced reserves which covers a total area of 123 km2, of which 60 km2 is completely free of feral cats, foxes and rabbits. Our mission is to facilitate the restoration of arid zone ecosystems through on-ground works, applied research and industry, community and government partnerships. Arid Recovery is dedicated to broad-scale restoration, beyond the fenced reserve throughout Australia’s arid lands. Initiatives include the development of a more economical rabbit, cat and fox-proof fence for general use, reintroductions of locally-extinct fauna, raising public awareness about arid zone conservation and serving as a demonstration site for broadscale feral species control, ecosystem restoration and successful partnerships. The pack is divided into the following sections: Section 1 - Impacts of Pest Animals Section 2 - Arid Recovery Fact Sheets 1. Rabbits and their control 1. What is Arid Recovery? 2. Dingoes 2. Greater Stick-nest Rats 3. Feral cats 3. Burrowing Bettongs 4. Foxes 4. Greater Bilby 5. Cat and fox control methods 5. Western Barred Bandicoot 6. Exclusion fencing 7. Vegetation recovery For further details regarding the information in this booklet please contact Arid Recovery. Arid Recovery PO Box 147 Roxby Downs SA 5725 [email protected] All fact sheets can be found on the Arid Recovery website: www.aridrecovery.org.au Section 1 Impacts of pest animals Feral cats, foxes and rabbits have contributed to the decline of many native mammals in Australia’s arid zone, yet many myths surround the activities of these pest animals. High numbers of pest animal predators, including dingoes, can also have negative impacts on livestock. For over a decade Arid Recovery has monitored the activity of feral animals both within the Arid Recovery Reserve and on surrounding pastoral lands. Section 1 of this Landholders Pack outlines the impacts of feral animals on native plants and animals and discusses some of the control methods used both within the Arid Recovery Reserve and in surrounding pastoral lands. Many of these practices can be implemented on pastoral lands to control feral animal numbers. Controlling the number of feral animals on the land through efficient and cost-effective practices can increase the overall productivity of land in the arid zone. Arid Recovery would like to thank the many landholders and volunteers that have assisted in gathering information about feral animals. If you would like any further information regarding control of pest animals in the arid zone, please contact Arid Recovery on 08 8671 8282 or visit the Arid Recovery website www.aridrecovery.org.au Map of the Arid Recovery Reserve showing the various expansions and habitats. 1. Rabbits and their control Activity Rabbits are not native to Australia. Since their introduction in 1859, rabbits occupy more than more than 60% of Australia and have a higher breeding rate than any native mammal. Prior to the release of the rabbit calicivirus, South Australia’s arid zone livestock industry suffered an estimated loss of $17.4 million each year due to rabbits. In summer and winter of 2002, Arid Recovery conducted a study into the home range, activity and habitat use of the European rabbit using radio-telemetry in arid Australia to improve management techniques in the arid zone. Benefits of rabbit control Some benefits of controlling rabbits include: • improving regeneration of native vegetation • reducing populations of introduced predators such as foxes and feral cats • minimising a key threatening process Surface activity was highest at night and lowest during the day. During winter, rabbits were most likely to be found in their warrens between 9am and 4pm. During summer, rabbits were most likely to be found in their warrens between 11am and 6pm. Rabbits spent considerable amounts of time on the surface, whether it was during winter or summer. This was somewhat surprising given that summer temperatures during the study often exceeded 35 degrees celcius. Habitat use Rabbits used both dune and swale habitat but most warrens and surface fixes were recorded in dune habitat during both Winter and Summer. Diet Rabbits have been found to feed on a variety of plants including mulga (Acacia aneura), roly poly (Salsola kali), parakeelya (Calandrinia remota). Control methods and recommendations Home range Average home range in summer: 2.1ha Average home range in winter: 4.2 ha No significant correlation between home range size and rabbit weight. The most successful control methods of rabbits included fumigation with phostoxin tablets, pressure fumigation with chloropicrin and warren ripping, where no significant perennial vegetation was present over the warren system. Warren ripping effectiveness was also improved when dogs were used to flush rabbits down warrens prior to ripping. If dogs can traverse a 300m buffer around warrens this will increase the chance that all resident rabbits have been flushed. All methods should be carried out between 9am and 4pm in winter and between 11am and 6pm in summer when rabbits are most likely to be down their warrens. Warren destruction using shovels and 1080 poisoning was unsuccessful in this study, however the effectiveness of poison baiting (using 1080 oats) may be increased by placing bait lines closer together in summer and concentrated in dune habitat and also in some warrens. Arid Recovery staff members using pressurised fumigation on a rabbit warren during 2002 study. 2. Dingoes Australia’s top order predator, the dingo, has been known to cause extensive damage to livestock during some seasons. Anecdotal evidence also suggests that dingoes may play a role in suppressing feral cats and foxes, major predators of Australia’s native fauna. The relationship between dingoes, cats and foxes has not yet been established experimentally and Arid Recovery’s ‘Dingo Project’, which began in 2007 aims to investigate this relationship using a landscape-scale pen trial – the first of its kind in Australia. A 37 km2 pen was built north of the dog fence, adjoining the northern boundary of the existing Arid Recovery Reserve. The pen was completed in December 2008 with a floppy top on the inside to stop animals involved in the trial from climbing out (below). All feral cats and foxes that were either in the pen when it was closed or were introduced into the pen were captured and fitted with GPS data loggers. A male and female dingo that were introduced into the pen from a neighbouring pastoral property were also fitted with GPS data loggers (above-male with radiocollar). Findings to date • • • • • • • All foxes (7 out of 7) were killed by dingoes within 17 days of being introduced to the enclosure Foxes died at night, late evening or early morning (where time of death was known) Half the foxes died on sand dunes and half died on swales Feral cats died between 20 and 103 days after release into the pen Half the cats (3 out of 6) were killed by dingoes Dingoes typically stayed with carcasses for several hours after death and/or returned to the carcass several times in following days. Deaths were confirmed by autopsy results, inspection of kill sites and GPS locations that were downloaded from the GPS data-loggers of dingoes, cats and foxes What this means and future steps Our results support anecdotal evidence that dingoes may play a role in suppressing introduced, medium-sized predators, particularly foxes, in arid environments. Whilst results suggest that dingoes could be used as a management tool to control introduced species north of the dog fence, we need to determine if native species will actually benefit from the reduction of cats and foxes from dingoes. Inside the Dingo Pen looking out. Note the floppy top is on the inside of the pen. 3. Feral cats Cats are not native to Australia and were most likely introduced prior to European settlement. They have adapted extremely well and feral cat densities often exceed one per square km in central Australia. Although they have not been exclusively linked to species decline they have been a contributing factor for many. Feral cats have been linked to the failure of threatened species re-establishing on islands and in the arid zone outside fenced reserves. In 2006, Arid Recovery investigated the home range and behaviour of feral cats and foxes in the arid zone using GPS technology (below) with the aim of improving management techniques using poison baiting. Home range Average total home range = 1740 ha Average core home range = 560 ha No significant difference in home range size between males or females. Activity Average minimum daily distance moved = 1519 m. A small male cat moved more than 45 km over 2 days. Another small male moved more than 26 km over 3 days. Long range movements such as these indicate that cats are able to quickly re-invade baited areas from non-baited areas. Cats preferred sand dunes and creek lines and avoided swales. Sand dunes and creek lines support thicker vegetation and key prey items such as rabbits. Cats were also found to take shelter in rabbit warrens. Average weight of cats in the Roxby Downs region is 3.8 kg. Heaviest cat on record from the Roxby Downs region was 7.3 kg Diet When abundant, rabbits are the principal prey for cats. However, when rabbit numbers are low cats have the capacity to switch to a variety of small vertebrates including reptiles and mammals. It is estimated that cat predation accounts for approximately 700 reptiles, 150 birds and 50 native mammals per square km killed in the Roxby Downs region each year. 4. Foxes Since the fox was introduced to Australia in the late 1800’s they have been linked to small mammal decline. Foxes have also been linked to the killing of lambs and other stock. Findings from Arid Recovery’s 2006 cat and fox collaring project gave a new insight into fox behaviour and activity in the arid zone using GPS data loggers (right-below). Home range Average total home range = 1660 ha Average core home range = 770 ha What sort of distance do foxes travel? Average minimum daily distance moved = 4553 m (significantly higher than cats). One large male fox moved almost 21 km in 2 days. Foxes prefer sand dunes and tend to avoid swales. Creek lines did not feature as a preferred habitat type for foxes. Rabbit warrens were also used as shelter sites and female foxes were known to use rabbit warrens as den sites (below). Average weight of foxes in the Roxby Downs region is 4.6 kg. Heaviest fox on record from the Roxby Downs region was 6.8 kg. Diet Foxes, like cats, can eat anything but if rabbits are abundant they are the foxes principal prey.. When rabbit numbers are low, foxes are opportunists and scavengers and will eat mainly invertebrates, such as scorpions, grasshoppers, beetles and centipedes. It is estimated that foxes consume on average 290 reptiles per square km and a few native mammals and birds in the Roxby Downs region each year. Feral cat with GPS data-logger collar. This cat from the Roxby Downs region contained 34 animals in its stomach including 32 reptiles, a zebra finch and a house mouse from one night’s hunting. A known fox den site in the sand dunes of the Roxby Downs region. Fox under sedation during radio-collaring process. Technology to improve trapping To reduce costs associated with the daily checking of permanent trap sites, Arid Recovery collaborated with a Melbourne-based company called Observant (www.observant.com.au) whose background was in setting up remote monitoring of water points on pastoral stations. This technology was adapted to enable remote checking of permanent trap sites via the internet. 5. Cat and Fox Control Methods For over a decade research has been undertaken on the Arid Recovery reserve on the methods to control introduced predators. The large home ranges that cats and foxes occupy in the arid zone, and the average distances they can travel each day, means a combination of poison baiting, trapping and shooting is recommended, rather than relying on a single method. Benefits of controlling predators: Some of the benefits of controlling introduced predators include: • increased productivity • re-establishment of native fauna to improve ecosystem health • protecting and increasing wildlife populations Tip: To find out more about our feral animal control techniques please contact Arid Recovery on 08 8671 8282. Trapping Fixed trap sites should be effective for both cats and foxes as they move continually throughout their home range. In 2000 and 2001 Arid Recovery investigated the effectiveness of different lures and found that lures significantly attracted more cats and foxes to trap sites, compared to trap sites that had no lures. Lures such as food, plants and cat urine are widely used to attract predators to traps. Small machines emitting bird/cat/ rabbit noises were found to be effective lures for both cats and foxes during the summer months. Arid Recovery has permanent trap sites (top right) around the perimeter of the Arid Recovery Reserve. These traps have contributed to the successful reintroduction of threatened species into the Reserve and have enabled an effective buffer zone around the Reserve. Each site is made up of a naturallooking corral and a pair of rubber foot-hold traps set at the entrance to each corral. Rubber foot-hold traps are much more humane than the older leg-hold jaw traps. Remote cameras are becoming increasingly popular for both feral animal control and native species monitoring. Arid Recovery has used a couple of different brands and has also used a digital video recorder. Poison baiting Handbaiting with 1080 poison baits was found to be most effective for controlling fox numbers. There are different requirements for both cats and foxes to ensure the most effective use of poisons. These have been found to be: • cats require baits to be laid out at a minimum of 25 baits per square km to detect one bait within 3 days. • foxes require baits to be laid at a minimum of 2 baits per square km to detect one bait within 3 days, but up to 5 baits per square km is highly recommended to allow for non-target uptake by birds and reptiles. To reduce the uptake of baits by non-target animals (particularly sand goannas) it is recommended that baiting is only conducted from March until November. Areas to target Whichever method is used to control cats and foxes in the arid zone, habitats with thick vegetation, particularly creek line and dune habitat or areas where there are rabbit warrens should be targeted for greater results. Waterpoints (including troughs and dams), homesteads and rubbish dumps are also prime areas to target. Poison Baiting Cat, fox and rabbit presence on transects during baiting trials. Note the significant decline in fox numbers but almost stable numbers of cats despite baiting efforts. Output photo from one of the remote cameras which clearly shows rabbits, time and even temperature. One of the permanent trap sites outside the Arid Recovery Reserve. Note the corral design. Problems with exclusion fencing Popped staples from kangaroos fighting through the fence. Recommendation: Control the number of bucks inside and outside fenced area. 6. Exclusion fencing Small scale exclusion fencing is becoming increasingly popular on private land to restore small patches of habitat. The unique fence surrounding the Arid Recovery Reserve is the only fence design in Australia that has been scientifically proven using pen trials to be an effective barrier to feral cats, foxes and rabbits. A number of fence designs were tested for performance to ensure maximum results in excluding predators and other feral animals. Testing A 20m x 20m pen was constructed (above) to test various fence designs Cats When the floppy top was not in place, cats escaped by climbing wooden posts or jumping onto the netting and climbing over the mesh fence. Foxes A total of 27 foxes were tested. Foxes were found to bash and bite at the netting of the fence. Rabbits A total of 24 rabbits were tested. Sub-adult rabbits, weighing up to 500g were discovered getting through conventional 40mm diameter hexagonal “rabbit-proof ” netting. To ensure fence is rabbit-proof, high quality 30mm hexagonal netting is highly recommended. Fence Features A total of nine different fence designs were tested and the following important features were found: • Floppy top. A 60cm curved ‘floppy’ overhang, bent to form a rounded arc rather than a 45 degree straight overhang, was important in excluding cats and foxes • Aprons. Horizontal foot aprons of no less than 30cm were sufficient to prevent animals from digging under the base of fences. • Corners. Exclusion fences should avoid internal corners and should use steel posts, rather than wooden posts to prevent animals from climbing. • 30mm netting. To ensure rabbit proofing this 30mm netting should extend 90cm from the ground. Optimal fence design (for cat, fox, and rabbit exclusion) The following fence design was used for the construction of the Arid Recovery Reserve’s first ‘paddock’ called the Main Exclosure covering 14 square km. No cats or foxes have breached this fence since it’s completion in 1998. The 1.80cm fence design with metal posts includes: • 60cm floppy overhang • 30mm netting up to a height of 90cm • 30cm apron at base • two electric wires, less than 10cm from the netting, at heights of 1.30cm and 1.60cm • a minimal number of corners Footnetting and apron rusting after 9 years in the field. Recommendation: Replace footnetting by either removing the old footnetting and clipping on new footnetting, or clip new footnetting over the top of existing or using plastic coated netting. Washouts after rain. Excluded animals could gain access. Recommendation: Always do post-rain fence checks as soon as possible and patch washed out areas with netting. Research from NZ found that it took less than two hours for one rabbit to gain access through a hole in a fence. Install culverts or flood gates. Sand build up. This can lower the overall height of the fence but also the height of the rabbit-proof netting. Recommendation: Increase height of rabbit-proof netting and minimise sand drift by encouraging revegetation and discouraging off road driving in the vicinity of the fencelines and capping dunes with gravel or clay. Gully erosion along fenceline destroying tracks. Water struggles to flow through the fence and creates gully erosion in big rain events. Recommendation: Consult professional grader operators who can identify key areas in the landscape for flood mitigation. During pen trials, a shorter (115cm high), non-electrified version of this fence design did not reduce the effectiveness of the design. This shorter design now surrounds Arid Recovery’s Red Lake Expansion and is being tested at a landscape scale. Material costs • At January 2005, the materials for the optimal fence design cost AUD $12, 432 per km. • For the 115cm fence design, materials cost AUD $8, 814. Fence products • Cheaper, imported wire products were highly variable in diameter size (marketed as 30mm with diameters up to 37mm) • 30mm netting used is a custom made product and contributed to 57% of material costs. If there is a greater demand for this then it might become a standard product. Side view of fence designs including location of selvage wires, electric wires and ‘floppy’ overhang. The Arid Recovery Fence. Section 2 Native animal fact sheets Australia’s arid lands have changed dramatically since European settlement. sixty per cent of the mammal species at Roxby Downs have become locally or completely extinct. Exclusion fencing, feral animal control and applied research have enabled Arid Recovery to bring back species from the brink of extinction. 7. Vegetation recovery Browsing by cattle and rabbits can limit the growth of some arid zone tree and shrub species. Rabbits alone can prevent regeneration of some arid zone shrub species causing population declines or local plant extinctions. A study conducted at the Arid Recovery Reserve aimed to quantify initial growth changes in shrubs after the removal of cattle and rabbits and the re-introduction of native herbivores including burrowing bettongs, greater bilbies, and greater sticknest rats. Growth of mulga, silver cassia and sandhill wattle was reduced or arrested by even low densities of cattle and/or rabbits. To improve or assist vegetation recovery: • fence off regenerating stands of mulga until juveniles have exceeded the browsing height of cattle • reduce stock density in paddocks where mulgas are regenerating Main findings Bilbies and bettongs are better diggers than goannas and rabbits, digging deeper and wider and excavating more soil. Bilby digs in particular, catch a greater amount of leaf litter and viable seeds (below) and carbon levels in the digs are higher than surface soils. Higher germination of seedlings was found in bilby digs. Bilbies dig up to 30cm for a single grain of rice, illustrating their great sense of smell. Bilby and bettongs play an important role in creating fertile patches in the landscape. Benefits of Bilbies What effects do animal digs have on soil nutrients? Rabbits, goannas, bilbies and bettongs are all accomplished diggers. They dig to create shelter in the form of burrows and warrens and to find food such as insects, roots and shoots. Their digging abilities and subsequent impact on surface soils have seen them described as the ecosystem engineers of the arid interior. However, since the 1930’s, bilbies and bettongs have become locally extinct throughout many areas of the arid interior. Arid Recovery, in conjunction with the university of NSW and the University of Adelaide investigated the impact that this decline had on soils. Bilby dig with a variety of seeds and leaf litter collected in the base of the dig. • • • • Increase seedling germination Improve soil health Stimulate plant production Control insect pests such as locusts Section 2 provides information on threatened species that have been successfully introduced into the Arid Recovery Reserve including the Greater Bilby, Greater Stick-nest Rat, Burrowing Bettong and Western Barred Bandicoot. Through monitoring programs we have identified that Arid Recovery now has five times as many naturally occurring small native mammals inside the Reserve compared to the outside. Although fenced reserves are important for the conservation of many of our threatened species, they are typically small in scale and very expensive to construct. Arid Recovery is also researching methods of restoring large areas of arid zone habitat without the use of fences to create a more naturally functioning native ecosystem. Arid Recovery would like to acknowledge the many volunteers, researchers and landholders that have assisted in the native animal monitoring programs. If you would like any further information regarding native animals in the arid zone, please contact Arid Recovery on 08 8671 8282 or visit the Arid Recovery website www.aridrecovery.org.au All fact sheets are available on our website www.aridrecovery.org.au • • All fact sheets are available on our website www.aridrecovery.org.au • • • • All fact sheets are available on our website www.aridrecovery.org.au • • • 1 0.8 0.6 0.4 0.2 0 bilby digs surface average seedling per dig % carbon 7 6 5 4 3 2 1 0 bilby dig rabbit dig surface All fact sheets are available on our website www.aridrecovery.org.au • • • • • • • All fact sheets are available on our website www.aridrecovery.org.au Contact Us For further information on any of the topics covered in this pack please contact Arid Recovery. Arid Recovery PO Box 147 Roxby Downs South Australia 5725 Phone: 08 8671 8282 Email: [email protected] All Arid Recovery Fact Sheets are available online at: www.aridrecovery.org.au Photo credits: Title: BHP Billiton, H. Crisp, Arid Recovery Section 1: Arid Recovery Rabbits and their control: Arid Recovery Dingoes: T. Moyle and H. Crisp Feral Cats: K. Moseby, P. Bird and J. Stott Foxes: H. Crisp and J. Stott Cat and fox control methods: J. Stott, M Farelly and Arid Recovery Exclusion FFencing: J. Read and BHP Billiton Vegetation Recovery: J. Edwards and Arid Recovery Section 2: A. James Acknowledgements: This publication was edited by Helen Crisp, Arid Recovery Ecologist, with input from Clint Taylor, Arid Recovery Pest Management Officer and Kimberley Jarman, Arid Recovery Volunteer and Community Liaison Officer. Useful comments and feedback were received from station managers and owners from the Outback Lakes (including Billa Kalina Station, Mulgaria Station, Muloorina Station, Dulkaninna Station, Clayton Station, Farina Station), Bulgunnia Station and Coondambo Station. Thanks also to (Peter Paisley, John Read and Katherine Moseby) for their assistance. 1. Rabbits and their control Moseby KE, De Jong S, Munro, N and Pieck, A (2005) Home range, activity and habitat use of European rabbits (Oryctolagus cuniculus) in arid Australia: implications for control, Wildlife Research, 32, 305-311. Ryan, SA, Moseby KE and Paton, DC (2002) Comparative foraging preferences of the greater stick nest rat and the European Rabbit: Implications for regeneration of arid lands. 2. Dingoes Moseby, KE, Neilly, H, Read, JL, and Crisp, H (In press) Dingoes prevent Red Fox re-establishment within a landscape scale enclosure: implications for threatened species in the Australian arid zone. 3. Feral cats Moseby KE, Stott J and Crisp H (2009) Movement patterns of feral predators in an arid environment – implications for control through poison baiting. Wildlife Research, 36, 422-435. Read JL, and Bowen Zoe (2001) Population dynamics, diet and aspects of the biology of feal cats and foxes in arid South Australia. Wildlife Research, 28, 195-203. 4. Foxes Moseby KE, Stott J and Crisp H (2009) Movement patterns of feral predators in an arid environment – implications for control through poison baiting. Wildlife Research, 36, 422-435. Read JL, and Bowen Zoe (2001) Population dynamics, diet and aspects of the biology of feal cats and foxes in arid South Australia. Wildlife Research, 28, 195-203. 5. Cat and fox control methods Moseby, KE, Selfe, R and Freeman, A (2004) Attraction of auditory and olfactory lures to Feral Cats, Red Foxes, European Rabbits and Burrowing Bettongs. Ecological Management and Restoration, 5, 228-230. 6. Exclusion fencing Moseby KE and Read JL (2006) The efficacy of feral cat, fox and rabbit exclusion fence designs for threatened species protection, Biological Conservation, 127, 429-437. 7. Vegetation Recovery Munro NT, Moseby KE and Read JL (2009) The effects of browsing by feral and re-introduced native herbivores on seedling survivorship in the Australia rangelands. The Rangeland Journal, 31, 417-426. Edwards J (2001) Monitoring vegetation change under different arid management regimes, near Olympic Dam, South Australia, using Landsat TM Imagery, Honours Thesis, The University of Adelaide. This publication was made possible through funding provided by the South Australian Government. © Arid Recovery, 2011 James AI and Elridge DJ (2007) Reintroduction of fossorial native mammals and potential impacts on ecosystem processes in an Australian desert landscape. Biological Conservation, 138, 351-359. Further Reading: Newell J (2008) The role of the reintroduction of Greater Bilbies (Macrotis lagotis) and Burrowing Bettongs (Bettongia lesueur) in the ecological restoration of an arid ecosystem: Foraging diggings, diet, and soil seed banks. PhD Thesis. The University of Adelaide. Arid Recovery Restoring Australia’s Arid Lands Arid Recovery is a joint initiative between BHP Billiton, SA Department for Environment and Natural Resources, the University of Adelaide and the local community.
