Potential Use of Contraception for Managing Wildlife Pests in Australia

There is an increasing level of interest in contraception to manage wildlife pests in Australia, due mainly to concerns over high recurrent costs, animal welfare, and the failure of current control techniques to prevent damage in some instances. We have developed criteria that need to be met for contraception to be successful for pest control: • Technology exists to reduce fertility • An effective delivery mechanism to treat wild animals exists. • The end result of reduced animal damage is achieved. • Effects are humane and nontoxic. • Product is target specific, cost effective, and environmentally acceptable

Potential Use of Contraception for Managing Wildlife Pests in Australia

There is an increasing level of interest in contraception to manage wildlife pests in Australia, due mainly to concerns over high recurrent costs, animal welfare, and the failure of current control techniques to prevent damage in some instances. We have developed criteria that need to be met for contraception to be successful for pest control: • Technology exists to reduce fertility • An effective delivery mechanism to treat wild animals exists. • The end result of reduced animal damage is achieved. • Effects are humane and nontoxic. • Product is target specific, cost effective, and environmentally acceptable

REVIEW OF RESEARCH ON CONTROL OF BIRD PESTS IN AUSTRALIA

The most significant damage inflicted by birds in Australia is to germinating cereal and to ripening sunflower and fruit crops. The main pests are several native psittacine and corvid species, silvereyes (Zosterops lateralis) and European starlings (Sturnus vulgaris). The economic cost of damage is largely unquantified. While losses to industries as a whole are often low, losses to individual growers may be severe, and losses are distributed patchily in space and time. Shooting is the most widely practiced and most ineffective bird control technique used in Australia. Despite the high numbers of birds killed, damage persists, and disturbance caused by shooting and scare devices may actually increase damage. Trapping and export of native birds is frequently suggested as a solution but would be ineffective for damage control. Illegal poisoning is thought to have caused significant reductions in some parrot populations, but has not prevented crop damage. Decoy feeding shows promise for damage control in winter cereals. One site attracted 4,000 cockatoos for most of the seeding and germination phase. For sunflower, the main problem is rendering the main crop less attractive than the decoy. Netting is cost-effective even at moderate to low levels of bird damage for intensive growing systems with new varieties of high-yielding stonefruit. Research is needed on techniques to assess the cost of damage. The cost-effectiveness of damage control techniques can then be assessed. There is also a need for more studies on the biology of pest birds, in relation to the potential mitigation of crop damage by habitat modification or changes in crop growing practices

A ROLE FOR FERTILITY CONTROL WILDLIFE MANAGEMENT IN AUSTRALIA?

Increasing community awareness of the moral and animal welfare issues associated with conventional pest animal control has focused interest on non-lethal alternatives, such as fertility control. In Australia, animal welfare organizations have proposed fertility control as a solution to pest problems with feral horses and kangaroos. Wildlife damage control achieved by non-lethal, non-toxic and humane means would have wide appeal and application. Importantly, assessments of effectiveness must focus on damage control, rather than fertility control, per se. Most tests of fertility control drugs and techniques examine effects on reproduction, rather than on population dynamics. Many tests and models have not been robust enough to allow clear conclusions about the usefulness of the technique in damage mitigation. The present role of fertility control in wildlife management in Australia is extremely limited. Its longer-term potential will depend on the successful outcome of future research, development and extension. It also requires an assessment of the economic, environmental and welfare implications of using fertility control for wildlife management. The main barrier to the use of fertility control to manage pest animals is the lack of delivery techniques suitable for widespread and abundant animals. If drugs become available that cause permanent infertility with a single dose, or if current research leads to a technique for the passive spread of anti-fertility agents via infectious organisms, the potential for population management by fertility control for some species, such as foxes, will be increased. No such drugs or techniques are currently available

Food quality, diet and reproduction of house mice on irrigated cereal farms

Breeding in field populations of house mice (Mus muscfllus L.) is usually seasonal,and this has often been attributed to seasonal fluctuations in the quality or abundance of food. Populations of house mice in Australia are subject to irregular-outbreaks, and previous authors have suggested that these plagues are causally linked to improved breeding which occurs when food supplies are temporarily improved by unusually favourable weather. This thesis examines the link between breeding and the quality and abundance of food supplies in the Murrumbidgee Irrigation Region, NSW, an area where plagues have occurred in the past. The research involved a combination of descriptive investigation, laboratory experiments and field experiments. Available seeds were monitored in six habitats on two cereal farms. Because of rotational cropping and irrigation, seeds were available in different habitats in different seasons. In all habitats mice were mainly. granivorous and their diet closely reflects the available seed types. Cereal grain spilt at harvest, and other stale seeds were the main food in the non­ breeding season. It was proposed that this low-quality food limited breeding. When milk-ripe grass seeds and cereal grains became available, mice switched their diet to these fresh foods. Breeding started about a month later. The onset of breeding in different habitats was asynchronous. These findings suggest that time of onset of breeding as determined by available food supplies. The hypothesis that breeding of mice in rice fields in spring is limited by food supplies which are inadequate in energy or quality was tested in a field experiment. Three types of supplemental food were provided ad libitum to mice in a rice field in spring 1981. The breeding performance of the mice was monitored by capture-mark-release censusing. After six weeks, banks with supplementary food supported a significantly higher proportion of breeding mice than control banks. There was no evidence of an effect on the breeding performance due to the different food qualities, and hence the energy content of the diet was probably the main factor limiting breeding. The hypothesis that breeding in rice fields in autumn and early winter is limited by poor food quality was also tested. At that time, mice on the farm ate a diet of nearly pure rice. and caged mice fed pure rice produced few or no litters. Supplements of casein or germinated rice grain significantly improved both litter production and litter size, but supplements of vitamin gibberellic acid (GA3) meal worms or milk-ripe rice grain did not. It was concluded that protein was probably the limiting nutrient for breeding of mice eating rice diets. A field experiment with a 2 2 factorial design was conducted in a rice stubble field in autumn 1983. It had been suggested in previous studies that high population densities might also lead to suppression of breeding by house mice. Therefore, population density was also included as a treatment in this field experiment. The treatments were supplementary High-protein Food or Low-protein Food and Culled or Unculled mouse numbers. Supplementary feeding increased the protein content of the diet from 8% to 11%, and was associated with a significant increase in the proportion of pregnant and lactating females on grids. Neither the culling treatment nor the interaction of culling X food quality had a significant effect on the proportion of breeding females. The results of the experiments indicate that onset of breeding in spring was limited by food availability, with an energy shortage probably the main factor,and that breeding in autumn was limited by food quality, with inadequate protein probably the main factor

Page 249

A comprehensive study has not previously been made of any aspects of the Banded Dotterel's ecology or behaviour. […] Two study areas were used for this research. One was the environs of Lake Wainono (Fig. 1), a small lagoon on the east coast of the South Island - a typical coastal wintering site for Banded Dotterels, which were present there throughout the year. The behaviour of nonbreeding flocks was observed from January to June 1977 there. Observations in this area were made on feeding preferences, techniques and habitats, daily routines, flock sizes and reactions to predators. The other study area was the Cass River delta (Fig. 2), near Lake Tekapo. This was a typical inland breeding ground and breeding behaviour was studied from June 1977 to January 1978. [Extract from Introduction

Towards Best Practice Vertebrate Pest Management In Australia

Australia has 26 species of introduced pest mammals that cause extensive damage to agriculture and the conservation of native wildlife. Past efforts tried to eradicate them. This focus on reducing pest numbers rather than the outcome, reduced damage, has had limited success. Under its Vertebrate Pest Program, the Bureau of Resource Sciences has developed principles and a strategic approach to managing pest damage. Close cooperation with land managers as co-researchers and co-learners is an essential element, as is a coordinated group approach to pest management. The approaches are illustrated with an example

Risk assessment for importing and keeping exotic vertebrates

Exotic animals can establish wild populations that may cause serious adverse economic and environmental impacts. In Australia, there are a number of species currently kept in captivity that would pose such threats were they to escape and establish. Paradoxically, there is a push to allow freer trade in animals between countries for recreational and commercial purposes. This paper considers approaches to assess and manage these risks, including the application of ecological theory to estimate the probability of escape, establishment, eradication, and harmful impact. Although some potential forms of impact are obvious, particularly for species that are pests in their natural or introduced range, others may be less so because species may change their behavior or ecology in new environments, and interact in unpredictable ways with resident plant and animal species. This uncertainty creates a need to leave a wide margin for error when assessing the risk of harmful impact

Risk assessment for importing and keeping exotic vertebrates

Exotic animals can establish wild populations that may cause serious adverse economic and environmental impacts. In Australia, there are a number of species currently kept in captivity that would pose such threats were they to escape and establish. Paradoxically, there is a push to allow freer trade in animals between countries for recreational and commercial purposes. This paper considers approaches to assess and manage these risks, including the application of ecological theory to estimate the probability of escape, establishment, eradication, and harmful impact. Although some potential forms of impact are obvious, particularly for species that are pests in their natural or introduced range, others may be less so because species may change their behavior or ecology in new environments, and interact in unpredictable ways with resident plant and animal species. This uncertainty creates a need to leave a wide margin for error when assessing the risk of harmful impact