A model based on data from research in New South Wales conducted by the Cooperative Research Centre for the Biological Control of Vertebrate Pest Populations suggests that the effectiveness of fertility control in reducing the abundance of foxes (Vulpes vulpes) can be strongly influenced by environmental variability. The model includes age-specific recruitment and survival as functions of resources indexed by rainfall. It is assumed that fertility control will affect only female foxes and that the use of a baiting regime to deliver a contraceptive agent will result in fixed proportional changes in pregnancy rates. By comparing the variability in the rate of increase of treated and untreated fox populations, the model predicts that: (i) frequent baiting, every one or two years, will be more effective than applications of baits at longer time intervals; (ii) the abundance of foxes will decline more rapidly, with higher levels of fertility control; (iii) infertility which lasts for only one breeding season is less effective than permanent sterility which allows for accumulation of sterile animals in the population; and (iv) highly variable results are likely to be the outcome of low-frequency baiting with an agent that produces only temporary infertility.

Quarterly spotlight counts of rabbits were conducted at three sites in central-western New South Wales. These counts commenced two years before the arrival of rabbit haemorrhagic disease (RHD) in the winter of 1996. The existing data on quarterly rates of change in rabbit abundance for the three populations provided a unique opportunity to study the effects of RHD on rabbit demography. Prior to the arrival of RHD, all three populations underwent phases of sequential increase and decrease in each year. On the basis of these patterns, RHD had a variable influence on the demography of the three rabbit populations. In 1996–97, the density of two populations declined over an expected period of increase, while at the third site the density increased as expected from pre-RHD patterns. Twelve months after their failure to generate expected positive rates of increase the two affected populations had returned to the normal sequence of increases and decreases in density although still at comparatively low numbers.

Summary1. This paper reports on the behavioural effects of surgical sterilization when used to simulate immunocontraception in free-ranging female foxes Vulpes vulpes . 2. During 3 years of trapping, 348 male and female foxes were fitted with transmitters in two treatment (females sterilized) and two untreated areas. 3. Radio-tracking indicated that sterile and fertile vixens maintained similar-sized territories during the breeding season, but that sterile females were possibly more likely to share their territories with each other. 4. There were no consistent differences in survival or dispersal between sterile and fertile females. 5. Outcomes from the study suggest that immunocontraception in free-living foxes is feasible.

This study describes temporal, spatial and individual variation in the diet of 255 red foxes (Vulpes vulpes) collected from agricultural land in central New South Wales from July 1994 to November 1996. Rabbits (Oryctolagus cuniculus), sheep (Ovis aries), eastern grey kangaroos (Macropus giganteus) and invertebrates were the most important food items overall. Significant seasonal variations, and sex and age differences between foxes occurred in the consumption of some food types. Some temporal synchrony was also evident, with different individuals often eating similar foods on the same night. This may have been related to moonlight. On full moon nights, foxes ate rabbits and small mammals significantly less often than during other moon phases. The management implications of variation in diet are discussed.

Agricultural riparian zones are often vulnerable to weed invasion and degradation of the physical streambank character through the trampling of livestock. Riparian zone restoration seeks to improve habitat biodiversity, minimise streambank erosion and improve water quality. In order for this to be effective land managers need to broadly understand the connections between riparian systems and adjoining agricultural ecosystems and to understand the habitat requirements of wildlife species adapted to the evolving riparian landscape. Common wombats (Vombatus ursinus) are abundant in the riparian agricultural landscapes of south-eastern Australia, but there is concern about their persistence in other landscapes. To understand the importance of riparian characteristics for wombats, we examined five physical and five vegetative characteristics associated with abundance of wombat burrows in the riparian zone of an agricultural landscape in south-eastern New South Wales, using two independent datasets. The abundance of wombat burrows increased substantially with increasing shrub cover in both datasets. There was weaker but consistent support for an association between wombat burrows and stream order and vegetation width. There were more burrows per metre by high than low order streams and burrows were most abundant at an intermediate vegetation width. In one of the two datasets, burrow abundance declined as the proportion of native shrubs in the shrub layer increased. As wombats are generally limited to riparian buffers in agricultural landscapes, these results are important as a first step toward managing and restoring the riparian zone. Restoration strategies, for example, may need to consider retaining patches of shrubs, even if they are weeds, whereas native shrubs are established in interspersed patches along larger rivers, in order to maintain suitable wombat habitat.