No abstract

A feral cat population was substantially reduced by poisoning at a semi-arid site in Western Australia. The control programme was designed to protect two species of endangered native mammals that had recently been reintroduced to the site. Feral cats were poisoned with carcasses of laboratory mice, each impregnated with 4.5 mg of sodium monofluoroacetate (1080). Baits were placed at 100-m intervals along the track system each night for four consecutive nights. Kill rates were assessed by monitoring survival of radio- collared cats and by spotlight counts of cats before and after baiting. All radio-collared cats were killed and there was a 74% reduction in spotlight counts of cats after baiting. Bait removal varied with the abundance of rabbits, the primary prey item for cats in this area. Effectiveness of control operations against feral cats is maximised by baiting at times of low prey abundance. Monitoring the changing abundance of the primary prey species provides important information for timing control operations against feral cats.

We present comparative success of various trapping methods trialed during control of feral cats at a site for the reintroduction of threatened mammals at Shark Bay, Western Australia. Our results come from 31 703 trap-nights that caught 263 cats (an average of 0.83 per 100 trap-nights). Cats differed markedly in their vulnerability to trapping depending on whether they primarily scavenged at rubbish tips or around human settlement or whether they hunted for their food in the bush. Cage traps were an effective means of controlling the former, with 9.4 cats captured per 100 trap-nights. Scavenging cats included a higher proportion of sub-adults and kittens and lower proportion of adult males than hunting cats. Variation between years in capture success for hunting cats was largely explained by the abundance of rabbits relative to that of cats and whether the rabbit population was increasing or decreasing. These factors accounted for a nine-fold difference in trap success. The number of cats caught in any particular trapping session could be explained by location (rubbish tip or town versus bush), trapping effort (typically greater effort yielded higher captures), abundance of cats at the site (captures were highest when cats were abundant), and season (captures were highest in the first half of the year when the young of the year were becoming independent). Concealed foot-hold traps, in a range of possible sets, provided effective methods for capturing cats that hunt, except where capture of non-target species was a critical limiting factor. Cage traps caught cats at a comparable rate to foot-hold traps for standard sets, but caught a significantly different cohort. Concealed foot-hold traps caught a higher percentage of adult cats, particularly males, than did cage traps. Mouse carcases and rabbit pieces were significantly more effective as lures when rabbits (the major food of cats at the site) were at low densities, whereas the success of commercial scent lures was unrelated to food availability. Significantly more cats than expected were caught using food as an attractant at times of food shortage (late summer, autumn and early winter) for both scavenging and hunting cats. In contrast, scent lures caught significantly more cats than expected in spring and summer when cats were defending access to mates and/or territory. Hence, no single trap type, trap set, or lure provided unequivocally superior performance over others. Control is likely to be best achieved by a variety of trapping methods and lure types used in combination, supplementing well timed poisoning efforts. Trap success is likely to be maximised by trapping at times when the dominant prey of cats are scarce relative to the number of cats and are decreasing in abundance.

This study describes the use of warrens and aspects of the social organisation of a population of the burrowing bettong, an endangered potoroid. Observations were made on 14 animals, maintained in a 4-ha enclosure of natural vegetation at Shark Bay, Western Australia. The population divided into three social groups, each of one male and one to many females. Individual bettongs used 1–10 warrens over a period of five months. Males changed warrens more often than females. Some females regularly shared warrens with other females. Many of these associations appeared to be mothers with their daughter or daughters. Sharing of warrens occurred regularly until the daughters were about 10 months old and occasionally after that. Day ranges of males were larger than those of females, exclusive of other males, and overlapped those of 1–6 females. Males shared warrens with the females within their day range. At night bettongs were not constrained to their day range and made use of the whole enclosure. Equal numbers of agonistic interactions between and within day-range groups, as well as the absence of feeding associations, indicated that bettongs operated independently of their day-range groups at night while feeding. Bettongs formed a weak dominance hierarchy with the oldest female on top and a young male at the bottom. Male–male interactions tended to be more aggressive than male–female interactions. Males were involved in significantly more agonistic interactions, particularly chases, than were females; chases usually entailed chasing another male away from a female. Use of space and social behaviour suggested a polygynous mating system.

ci6n en el continente y de supervivencia en Ms islas cOstera~ es mds consistente con la presencia (en el continente) o ausencia (en las islas) de predadores tntroducidos (zorros y gatos) y herblvoros (conejos y ganado).