Management of donkeys in the Kimberley
The Kimberley Rangelands Biosecurity Association has managed feral donkeys in the Kimberley since 1978 through two main phases.
Phase 1: Population Reduction (Management Culls) At the start of the program, donkey densities exceeded one animal per km². Several stations were targeted each year, with removals reaching up to 150 animals per helicopter hour. Nearly 505,000 donkeys were removed during this phase, not including animals culled by individual landholders or other organisations.
Phase 2: Judas Program When removal rates fell below 20 animals per helicopter hour, the program shifted to the Judas technique to target remaining animals. Radio-collared “Judas” donkeys were released to locate others. This phase began in 1994 in the West Kimberley, 1995 in Halls Creek, and 1997 in the East Kimberley.
A Judas network was established by collaring donkeys every 7–12 km, depending on terrain, to match estimated home ranges of 5–45 km². Once a property was declared eradicated, Judas animals were monitored for three additional dry-season runs and again the following year.
Benefit cost analyses
Two recent benefit–cost analyses were undertaken to assess the cost-effectiveness of different options for the KRBA’s donkey control program.
30-Year Forward Analysis
Four management scenarios were evaluated:
1. Current Control
Maintains the existing level of effort, resulting in an estimated 3% annual increase in donkey numbers.
- Benefit–Cost Ratio (BCR): 2.1
- Net Present Value (NPV): $2.623 million.
- Each $1 spent returns approximately $2.10
2. Maintain numbers
Slightly increases control effort to keep donkey numbers stable.
- BCR: 2.6
- NPV: $3.831 million.
3. Eradication
Assumes donkey numbers are halved each year until extremely low, with increases only through migration.
- BCR: 2.0
- NPV: $3.934 million.
4. Stop for ten years then resume
Pauses control for 10 years, then resumes in Year 11, ultimately ending with similar numbers to Option 2.
- BCR: 2.1
- NPV: $2.468 million.
40-year Program Review
A second analysis examined the cost-effectiveness of the program across its full 40-year history.
- Total expenditure to date: $8.4 million.
- When adjusted for inflation and opportunity cost: Present cost value = $78 million
- Estimated present value of benefits: $268 million
- Net Present Value: $220 million
- Benefit–Cost Ratio: 3.8
These results show the program has delivered excellent economic value to the pastoral industry. Only direct economic costs and benefits were included in these analyses.
Additional Benefits (Not Included in the Analyses)
A second analysis examined the cost-effectiveness of the program across its full 40-year history.
- Opportunistic removal of other large herbivores and feral pigs
- Reduced environmental damage
- Lower biosecurity risk
- Faster detection of significant weed infestations (Examples include the discovery of prickly acacia and mimosa pigra infestations in the East Kimberley by DPIRD Biosecurity Officers while conducting aerial donkey control. The unfamiliar plants were identified after landing to inspect, leading to active eradication programs that have since made significant progress.)
- Reduced nuisance impacts on cattle operations
Wild dog control in the Kimberley
Currently, the Kimberley Rangelands Biosecurity Association runs two aerial baiting programs each year: the first in May, followed by the second in late September. These programs are designed to supplement ground baiting carried out by individual stations by giving land managers access to more remote areas of their properties and enabling the rapid deployment of baits in those locations.
Cattle enterprises across the Western Australian rangelands have reported significant and increasing levels of damage and losses from wild dogs. Calves are particularly susceptible to attack, while attacks on adult cattle may not be lethal but can significantly impact their productivity. The costs also flow through to the processing sector, with bite marks and scarring downgrading carcass values. The extent of economic losses due to wild dog predation is difficult to quantify, particularly under the extensive rangeland grazing conditions in Western Australia. Pastoral Lands Board annual returns from 2007 to 2014 show an increase in stock losses from $2.4 million to more than $6.0 million across the WA Pastoral Region.
Current wild dog management activities in the Kimberley region are estimated to provide very good returns on investment (Benefit–Cost Ratio = 5.1), according to the Western Australian Wild Dog Action Plan. Management is partially focused on aerial baiting at relatively low cost compared with control activities in other regions. Although benefits are also relatively modest, they far exceed the associated costs.
Western Australia has a unique and internationally recognised biodiversity. There is recognition of the cultural and conservation value of the dingo within the conservation estate, as well as acknowledgement of the need to consider a range of landscape values including ecological, wildlife movement, cultural and heritage values. Conservation of dingoes is considered an important goal. For livestock producers, the key challenge is managing the clear risk of continuing wild dog encroachment into agricultural regions where they disrupt livestock production. Wild dog management is complex and requires balancing the economic imperative to reduce impacts on pastoral and some agricultural enterprises with the conservation values of the dingo and community expectations for humane treatment of all animals.
