The status and impact of the Rainbow lorikeet (Trichoglossus haematodus moluccanus) in south-west Western Australia.
Department of Agriculture and Food, Western Australia, Perth. Report 04/2005.
Rainbow lorikeets Trichoglossus haematodus moluccanus were first recorded in Perth in 1968 and the population was thought to have originated from fewer than 10 birds that were either deliberately released or had escaped from aviaries. Since the early 1960s, the population has increased exponentially and spread rapidly over 174 km2 of the metropolitan area. The population now numbers an estimated 8,400 birds and is expanding in range at a rate of 0.7 km per year. Rainbow lorikeets are highly mobile, have generalised feeding and breeding requirements and can quickly adapt to exploit new feeding and breeding resources. They have taken advantage of the year-round supply of native and exotic food plants available in Australia’s major cities and are expanding in number and distribution in Brisbane, Sydney, Melbourne, Canberra, Adelaide and Perth. The rainbow lorikeet is regarded as either a pest of agriculture or an unwanted organism in New Zealand, the Northern Territory, Queensland, the Australian Capital Territory, Victoria, Tasmania and South Australia. It is also a major pest of agriculture in the Northern Territory, Queensland and the fruit growing regions of the Adelaide Hills in South Australia. Analyses conducted in this study show that the feral rainbow lorikeet population in Perth poses an extreme risk to the State’s social, environmental and agricultural values. Rainbow lorikeets cause a nuisance in the form of noise, damage to backyard fruit crops and fouling of outdoor areas and vehicles with droppings. The large roosting flock of over 1000 birds near Perth domestic airport may also pose a risk of bird-strike to aircraft.
The lorikeets also exclude native birds from feeding resources and nesting sites, kill the nestlings of other bird species and carry Psittacine beak and feather disease in the liver (once infected), which they can spread to native lorikeets and parrots. Lorikeets are a serious pest of cherries, apples, pears and stone fruit and a very serious pest of grapes in Australia and this study showed that the potential for rainbow lorikeets to spread outside the Perth metropolitan area is high. Thus, the lorikeets pose an extreme threat to Western Australia’s $245 million fruit, nut and grape growing industry. An integrated pest management program must be developed to: restrict the population to the Perth metropolitan area, and reduce the number of birds in the population from an estimated 8400 in 2004 to an estimated 5000 by 2020. The management program should include the following objectives:
- Investigate sources and obtain the funding required to manage the population.
- Estimate the number of birds in the Perth population, establish its distribution and locate major roost sites.
- Alter the status of the rainbow lorikeet in south-west Western Australia so that it is a declared pest in the metropolitan area (alter to A2; ‘subject to eradication in the wild’ south of the 20th parallel of latitude, and A5; ‘numbers to be reduced/controlled’ in the Perth metropolitan area).
- Investigate methods of population reduction in the metropolitan area and document their effectiveness.
- Educate the public on the impacts of rainbow lorikeets and the need for control.
- Eradicate rainbow lorikeets that are sighted outside the metropolitan area.
- Investigate and document the effectiveness of methods for the mitigation of agricultural damage.
- Conduct a cost/benefit analysis of the damage caused by rainbow lorikeets and lorikeet control.
- Develop a molecular approach to population control and management.
- Review standards for the import and keeping of rainbow lorikeets to reduce the risk of aviary escapes.