News Archive

The annual prickly acacia wet season program in the East Kimberley was completed in February just prior to a week of good rains that will help with the uptake of the applied chemical.  Of the two control runs done over the wet a total of 95 plants were removed including just one seeding plant.  This is the second consecutive year the numbers of plants found has been under 100 and only a fraction of the 9,000 plus initially removed in 2010. 

All the seeds off the one plant were collected and destroyed on site. The East Kimberley rubber vine program started in early May with an initial aerial survey that covered approximately 30,0000 hectares, very few seeders were found in the existing control area however a new infestation covering approximately 13 hectares was found 11 kilometres away from another existing outlier infestation and 26 kilometres from the core infestation.  Estimates put the initial control at this location to take up to three weeks with follow up work for at least three to five years.

The West Kimberley rubber vine control program will start in July, the survey work due for earlier this year was suspended due to a lack of flowering.  The survey uses camera technology to identify rubber vine flowers by their distinctive colour so without flowers the survey cannot be run successfully.  In a normal year this method of detection has been demonstrated to have about a 30% higher success rate of finding plants compared to human observers.  

Earlier this year long-time Kimberley shooter for DPIRD ‘Mick Everett’ sadly passed away in Perth.  Mick was a very popular figure in the region, particularly within the pastoral industry having been involved in aerial shooting programs since the early 1980’s.  He was the DPIRD coordinator for our ‘Judas’ donkey program in the Kimberley and at times would assist in a similar program in the Pilbara.   

A few years back he also got involved in rubber vine survey work in the West Kimberley with John Symanski’s Aquila program.  The annual survey uses cameras mounted on a chopper to find plants along the Fitzroy River but in the development of the techniques both human observers and the cameras were used in unison to properly test and refine those techniques. 

Mick’s last job for us was a five day cull in December last year of wild horses and camels south of Halls Creek under trying conditions.  

His knowledge of the local landscape and the people who operated within the region was huge and he was widely acknowledged as one of the good guys.  He will be greatly missed at both a professional and personal level right across the Kimberley. 

In 2017 the KRBA provided funding through the Royalty for Regions program to the Australian Wildlife Conservatory (AWC) to expand an existing study looking at automatic feeder traps as a method of control for feral pigs.  That project came to an end in December 2019.  Following is a summary of the program and some of its results.    

There were five components to the research that were investigated over the duration of the project: 

1. Investigate the best method for attracting feral pigs to bait stations and traps. 
2. Develop and test an automated bait station that can be transported by helicopter, used in remote areas and left for long periods unattended. 
3. Develop and test trap set-ups suitable for helicopter slinging for use in remote areas. 
4. Gather data of pig damage throughout the year at specific swamps, before and after pig control efforts. 
5. Gather and analyse location and habitat data using GPS collars, to determine -  

• How far pigs travel and how this varies with seasonality. 
• Home range size and overlap for male and female pigs. 
• Habitat requirements and how behaviour changes throughout the day and night. 
• What are the drivers for pig presence in the Kimberley.   

Automated feeders were constructed and erected in areas, across a range of pig densities.  All feeders had two cameras facing the feeder to identify if a subset of pigs would come in to the feeder but not feed from it.  In addition, a feeding experiment was conducted at a station’s bone pit, where cameras were deployed on both the automated feeder and pit to examine which food source was preferred.     A total of 20 feral pigs were fitted with GPS collars in three areas to encompass a latitudinal spread across the rainfall gradient and to enable research on differing land uses (pastoral and properties managed for conservation).  All collars ran for more than 2 years after deployment. 

 A trial was undertaken using the placebo version of the commercially produced “Pig-out” bait.  While the baits seemed palatable their use was ruled out as they are prone to drying out when exposed to the air and are relatively expensive.  A previous study in the Kimberley trialled the use of 1080 laced grain, which was found to be very successful.  At the time of the project lacing grain with 1080 to target pigs was not permitted however this was changed in 2019 and is now permitted under the code of practice for the safe use of 1080, PAPP & strychnine. This means approved pastoralists can now access 1080 concentrate for the purposes of lacing grain to target pigs.  

 Two experiments were undertaken to look at different ways of introducing poison to pigs.   First was a trial using grain, offered in piles adjacent to the feeder to see how much grain would have been consumed by pigs.    This would help calculate how much laced grain will be required when undertaking trials using poison.  The largest group of pigs observed in a single event did not exceed 15 animals.  It is estimated that to kill a group of this size at least 10 kg of laced grain should be deployed.  Also trialled was the use of gel capsules dispersed through heaped grain. The idea being that the capsules were small enough to be consumed along with the grain.  Initial results were promising as pigs consumed the capsules but it’s unlikely that this method could be used in the short term as it will need more evidence to be potentially registered as an approved method.   

 In brief, the research has achieved the following –

• Successful development of an automated baiting system that can be deployed for control of feral pigs in remote parts of the Kimberley, and optimised the delivery of baits using that system. 
• Identification of movement patterns of pigs in the central and western Kimberley, including differences in habitat use across the rainfall gradient from north to south.  

Modelling conducted by AWC shows that suitable habitat for feral pigs is much larger than the area currently occupied and pigs are still expanding throughout the Fitzroy Basin and in the North Kimberley, there is a significant potential for the spread of feral pigs due to the high rainfall and the many small rivers that dissect the region.  

 Feral pig management in the north will be complex as pigs are likely to be dispersed throughout the area due to the abundant water.  In the south, however, pigs are largely constrained to the larger watercourses, particularly in the drier parts of the year. 

Work continues on the prickly acacia infestation that is scattered over 10,000 hectares to the west of Wyndham.  Less than 100 plants were found and controlled on the site in October of this year.   Recent fires made the work difficult with many plants burnt or just half burnt meaning some plants may not take up the chemical applied.  Only two seeding plants were found this year, the seed pods from those plants were removed and deep buried on site to ensure that the wild cattle in the area would not eat the seed and cause its spread.  

Rubber vine plant numbers controlled in both the East and West Kimberley continues to decline.  In the east 3,471 plants were located, just over half the plants found in the previous year.  In the west just 728 plants were found of which only 16 vines were mature.  

The KRBA’s Field Officer “Blu’ carried out a survey of grader grass in the North Kimberley.  In many locations the density and extent of the plant had increased significantly since the North Kimberley LCDC survey in 2011.  In some spots the movement along roads was measured at more than 20 kilometres in the eight years between surveys.   The KRBA will be carrying out field trials in conjunction with some land managers across the Kimberley this wet season to gauge the effectiveness of new chemicals and methods of application on grader grass.  Additionally we will be keeping an eye on similar work being done in the NT looking at other means of control.

The committee is pleased to announce it has a new member joining its ranks as of the AGM in October.  New Board Member Linda Evans from Napier Downs adds a ‘West Kimberly’ dimension to the group and will be a valuable asset. Meanwhile both Rick Ford and Lynette (Jim) Craig put up their hand to serve another three year term.  Lynette has been a member of the committee since the KRBA formed out of the old ZCA’s in 2010 whilst Rick has been a member since 2013. Mike Shaw was once again elected Chairperson with Lynette Craig taking up the Vice Chair’s role.

In 2019 two benefit cost analyses were undertaken to provide an estimation of the cost-effectiveness of various options for the Kimberley Rangelands Biosecurity Association’s feral donkey control program in the Kimberley region.  Only the economic benefits and costs of feral donkey control were considered, it is emphasised that other benefits include the opportunistic removal of other large herbivores and pigs, reduced environmental impact, reduced biosecurity risk, more timely identification of significant weed infestations, and reduced nuisance value for the cattle industry. 

The first analysis looked forward over a 30 year time period with four different options considered - 

• Current control: This option represents the current level of donkey control resulting in a 3% increase in donkey numbers through time.  This option gave a Benefit Cost Ratio of 2.1 with a net present value gain to the pastoral industry of $2,623,000 over the 30 years.
• Maintain numbers: This represents a small increase in control effort compared to current effort, such that current donkey numbers in the region are maintained over the 30 year time horizon.  This option gave a Benefit Cost Ratio of 2.6 with a net present value gain to the pastoral industry of $3,831,000 over the 30 years. 
• Eradication: This option reflects halving donkey numbers in the region each year until donkey numbers are kept low, only increasing through migration.  This option gave a Benefit Cost Ratio of 2.0 with a net present value gain to the pastoral industry of $3,934,000 over the 30 years.
• Stop control for 10 years then start again: This option represents a break from control activities for 10 years, then starting again in year 11 through to 30 with control effort resulting in a similar number of donkeys in the region after 30 years as is expected from option 2.  This option gave a Benefit Cost Ratio of 2.1 with a net present value to the pastoral industry of $2,468,000 over the 30 years.

The second analysis provided an estimation of the cost-effectiveness of the program over the last 40 years.  The results suggest that the program has provided excellent value for money. The Association has spent approximately $8.4million over the 40 years life of the program. Adjusting this value for inflation and compounding it to account for the opportunity cost of investing this money elsewhere, this has an estimated present value of $78million.  The benefit derived from this effort is estimated to be $268million (in present values and accounting for inflation). The Net Present Value (the difference between the benefits and costs) is estimated to be $220million and the Benefit Cost Ratio (the ratio of the benefits to costs) is estimated to be 3.8 (for every dollar spent, the ‘bang for the buck’ is $3.80).

Grader grass is thought to have entered the Kimberley region relatively recently. Although it is not yet widespread across all the region it is common in parts of the North Kimberley. In particular along sections of the Gibb River, Kalumburu and Mornington Roads. Infestations range from a scattering of plants on the road verge to large swathes moving away from the road down table drains. Grader grass seeds are not adapted for dispersal by wind or water so its spread is primarily been associated with earth moving equipment and collecting seed in the radiator or under carriage. It can rapidly grow up to two metres tall, sometimes reaching full height within 6-8 weeks. Seed heads can appear within 5-6 weeks of germination but much earlier on late germinations. It generally germinates at the onset of the wet season and typically starts to seed from February through to April.

It is an undesirable species in grazing and conservation areas of Australia. It can invade both native and improved pastures and, due to its low palatability, greatly reduce animal productivity if it becomes the dominant species. It is an opportunistic invader which when established competes strongly with existing and establishing perennial grass tussocks, particularly in overgrazed and degraded pastures and disturbed areas. Because it is generally ungrazed grader grass can generate large fuel loads increasing the risk of wildfires. These impacts on ecosystems are often long-term or irreversible.

Currently the RBG is mapping as many of the known infestations as possible. This work will be ongoing over the dry season along with documenting different control strategies both in the Kimberley and the Northern Territory. The information once gathered will be made available to land managers and other stakeholder groups and could potentially influence direction of the organisation’s own weed programs. This is a weed that could potentially become common across the Kimberley and if so would become a significant problem for land managers.

If you think you may have seen grader grass please contact our Field Officer Blu Gaff on 0429 171 016. Grader Grass is currently not a declared weed in the Kimberley but that may change in the future.

The RBG committee is very pleased to announce that it has a new Executive Officer joining the ranks. The fulltime position has been split into two part time positions. The existing Executive Officer – Dick Pasfield will be joined by Nerylie (Blu) Gaff. Blu has had extensive experience in weeds, in particular neem control in the East Kimberley region and also has a lot of experience working with farmers on their own control programs around Kununurra. Blu will start her position in late April and will be heavily involved in engagement with the membership as well as some of the weed work around the region.

Two new pastoralists have recently joined the RBG committee, John Gedders from Roebuck and James Camp from Kalyeeda Station. This gives the committee a good geographical perspective east - west but it was acknowledged at the recent AGM it does lack input from the north Kimberley. Mike Shaw from Spring Creek was once again elected to the Chair’s position at the AGM. Mike has been now in the position for four years.

By now some of you would have noticed warning signs alerting both visitors and locals that poison baits are present on pastoral stations. In all there are twenty signs erected by the RBG between the De Grey River and the Duncan Road turn off in the Northern Territory. Six of these signs are on Shire roads and fourteen are in designated 24 hour rest areas. Unfortunately Mainroads WA did not allow any signage on their roads however the numbers of caravans that pull up into rest areas during the dry season gives those signs very good exposure. In a count of caravans in July some of that larger rest stops had in excess of 50 vans in them, whilst the smaller ones still had ten or more.