Suchergebnisse

Abstract Context The introduced house mouse (Mus domesticus) causes significant economic damage to Australia's agricultural enterprises. As part of the Marna Banggara Rewilding Project on the southern Yorke Peninsula (SYP), the present study focused on the eastern barn owl (Tyto alba delicatula) as a potential bio-controller of mice, by providing nesting spaces where natural hollows are limited. Aims To design an appropriate pole-mounted wooden nest box, and to enhance barn-owl-breeding and house-mouse-hunting capacity on farmland adjacent to remnant native vegetation. Methods A prototype nest box was collaboratively designed with a nest box manufacturer using data from previous barn owl studies and anecdotal reports. Eleven pole-mounted wooden boxes with platforms were installed at distances >1.4 km apart on properties near Warooka, southern Yorke Peninsula (SYP), and monitored over a 6-month period using external trail cameras. Key results Of the 11 nest boxes installed, 55 percent were colonised within a month after establishment, and 82 percent were colonised within 7 months. Occupied nest boxes were actively used by paired owls for mating, breeding and rearing of chicks, which resulted in up to 35 fledgling owlets. Conclusions The nest box design successfully supported eastern barn owl colonisation and reproduction on the SYP. The inclusion of the platform not only provided easy, minimally invasive monitoring of barn owl activity and prey intake by researchers, but also increased usable space for barn owl behaviours, such as copulation and wing flapping. Implications The important nest box design elements featured in this paper, such as the platform, high entrance hole, predator-proof pole and rear door access, can be implemented in barn owl conservation, research and on farms where alternative nesting sites are limited.

Context
Feral cats (Felis catus) impact the health and welfare of wildlife, livestock and humans worldwide. They are particularly damaging where they have been introduced into island countries such as Australia and New Zealand, where native prey species evolved without feline predators. Kangaroo Island, in South Australia, is Australia's third largest island and supports several threatened and endemic species. Cat densities on Kangaroo Island are thought to be greater than those on the adjacent South Australian mainland, based on one cat density estimate on the island that is higher than most estimates from the mainland. The prevalence of cat-borne disease in cats and sheep is also higher on Kangaroo Island than the mainland, suggesting higher cat densities. A recent continental-scale spatial model of cat density predicted that cat density on Kangaroo Island should be about double that of the adjacent mainland. However, although cats are believed to have severe impacts on some native species on the island, other species that are generally considered vulnerable to cat predation have relatively secure populations on the island compared with the mainland.

Aims
The present study aimed to compare feral cat abundance between Kangaroo Island and the adjacent South Australian mainland using simultaneous standardised methods. Based on previous findings, we predicted that the relative abundance of feral cats on Kangaroo Island would be approximately double that on the South Australian mainland.

Methods
Standardised camera trap surveys were used to simultaneously estimate the relative abundance of feral cats on Kangaroo Island and the adjacent South Australian mainland. Survey data were analysed using the Royle–Nichols abundance-induced heterogeneity model to estimate feral cat relative abundance at each site.

Key results
Cat abundance on the island was estimated to be over 10 times greater than that on the adjacent mainland.

Conclusions
Consistent with predictions, cat abundance on the island was greater than on the adjacent mainland. However, the magnitude of this difference was much greater than expected.

Implications
The findings show that the actual densities of cats at local sites can vary substantially from predictions generated by continental-scale models. The study also demonstrates the value of estimating abundance or density simultaneously across sites using standardised methods.