Dingo interactions with exotic mesopredators: spatiotemporal dynamics in an Australian arid-zone study

2015 ◽  
Vol 42 (6) ◽  
pp. 529 ◽  
Author(s):  
T. Schroeder ◽  
M. M. Lewis ◽  
A. D. Kilpatrick ◽  
K. E. Moseby

Context Apex predators occupy the top level of the trophic cascade and often perform regulatory functions in many ecosystems. Their removal has been shown to increase herbivore and mesopredator populations, and ultimately reduce species diversity. In Australia, it has been proposed that the apex predator, the dingo (Canis dingo), has the potential to act as a biological control agent for two introduced mesopredators, the red fox (Vulpes vulpes) and the feral cat (Felis catus). Understanding the mechanisms of interaction among the three species may assist in determining the effectiveness of the dingo as a control agent and the potential benefits to lower-order species. Aims To test the hypotheses that feral cats and foxes attempt to both temporally avoid dingoes and spatially avoid areas of high dingo use. Methods Static and dynamic interaction methodologies based on global positioning system (GPS) telemetry data were applied to test temporal and spatial interactions between the two mesopredators (n = 15) and a dingo pair (n = 2). The experimental behavioural study was conducted in a 37-km2 fenced enclosure located in arid South Australia. Key results The dynamic interaction analysis detected neither attraction nor avoidance between dingoes and cats or foxes at short temporal scales. There was no suggestion of delayed interactions, indicating that dingoes were not actively hunting mesopredators on the basis of olfactory signalling. However, static interaction analysis suggested that, although broad home ranges of cats and foxes overlapped with dingoes, core home ranges were mutually exclusive. This was despite similar habitat preferences among species. Conclusions We found that avoidance patterns were not apparent when testing interactions at short temporal intervals, but were manifested at larger spatial scales. Results support previous work that suggested that dingoes kill mesopredators opportunistically rather than through active hunting. Implications Core home ranges of dingoes may provide refuge areas for small mammals and reptiles, and ultimately benefit threatened prey species by creating mesopredator-free space. However, the potential high temporal variation in core home-range positioning and small size of mutually exclusive areas suggested that further work is required to determine whether these areas provide meaningful sanctuaries for threatened prey.

1998 ◽  
Vol 46 (6) ◽  
pp. 617 ◽  
Author(s):  
J. L. Read

Ctenotus skinks are the most diverse and abundant diurnal reptile genus at Olympic Dam, in the South Australian arid zone. The home range, demography, reproduction and diet of five syntopic Ctenotus species was studied over a 6-year period in chenopod shrubland. Longevity frequently exceeded three years in C. regius, four years in C. schomburgkii and five years in C. leonhardii, with a 7-year-old specimen of C. leonhardii being recorded. Females of most species tended to be larger and lived longer than males. Two eggs were typically laid by each species in early summer. Annual reproductive effort, particularly in C. leonhardii, varied considerably depending upon the prevailing environmental conditions. All local species apparently occupied home ranges, with maximum recapture radii in different species of 40–60 m. Ctenotus appear to be unspecialised insectivores, although plant material and lizards are sometimes eaten by the larger species.


2004 ◽  
Vol 31 (6) ◽  
pp. 651
Author(s):  
G. Story ◽  
J. Scanlan ◽  
R. Palmer ◽  
D. Berman

Rabbit haemorrhagic disease virus (RHDV) escaped from quarantine facilities on Wardang Island in September 1995 and spread through South Australia to Queensland by December 1995. To determine the impact of this biological control agent on wild rabbit populations in Queensland, shot sample and spotlight count data were collected at six sites. RHDV spread across Queensland from the south-west to the east at a rate of at least 91 km month–1 between October 1995 and October 1996. The initial impact on rabbit density appeared highly variable, with an increase of 81% (255 ± 79 (s.e.) to 385 ± 73 rabbits km–2) at one site and a decrease of 83% (129 ± 27 to 22 ± 18 rabbits km–2) at another during the first outbreak. However, after 30 months of RHDV activity, counts were at least 90% below counts conducted before RHDV arrived. Using a population model to account for environmental conditions, the mean suppression of rabbit density caused by rabbit haemorrhagic disease (RHD) was estimated to be 74% (ranging from 43% to 94% between sites). No outbreaks were observed when the density of susceptible rabbits was lower than 12 km–2. Where rabbit density remains low for long periods RHDV may not persist. This is perhaps most likely to occur in the isolated populations towards the northern edge of the range of rabbits in Australia. RHDV may have to be reintroduced into these populations. Further south in areas more suitable for rabbits, RHDV is more likely to persist, resulting in a high density of immune rabbits. In such areas conventional control techniques may be more important to enhance the influence of RHD.


2010 ◽  
Vol 58 (4) ◽  
pp. 205 ◽  
Author(s):  
David Peacock ◽  
Ian Abbott

We reviewed historical literature and obtained nearly 200 records of the mongoose in Australia up to 1942. Although the earliest importations (from 1855) were for its snake-killing prowess, often as entertainment, its perceived potential as a control agent for the European rabbit (Oryctolagus cuniculus) plague saw concerted introductions made in New South Wales, Victoria and South Australia, primarily in 1883 and 1884. At least 1000 mongoose were released to control rabbits at 14 reported release locations in these states. As many as 700 of these mongoose were reported released in one New South Wales rabbit-control trial. These numbers indicate that insufficient propagule pressure does not explain why Australia escaped the additional devastation of an established mongoose population. The only reason stated for the failure of the mongoose releases to control rabbits is destruction of the mongoose by rabbit trappers, both inadvertently and in seeking to protect their employment. Unfavourable climate was implicated by CLIMATCH modelling in the failure of all releases, especially those into semiarid areas such as western New South Wales. No contemporary detail could be located of the reported 1884 failed introduction of ‘numbers’ of mongoose into North Queensland to control rats in sugarcane plantations.


1965 ◽  
Vol 13 (3) ◽  
pp. 461 ◽  
Author(s):  
JJ Lynch

The distribution of Lymnaea tomentosa, the intermediate host of Fasciola hepatica Linnaeus, in Australia is described and studies of its ecology in two separate areas represented by (1) streams, associated springs and swamps, and (2) the unique habitats along the margins of the Murray lakes, are reported. The relative density of snail populations in both of these areas was recorded over 4 yr and the fluctuations in population were shown to be related to factors controlling the presence of water in the habitat, water temperature, and the occurrence of a native predatory fly (Dichaetophora biroi Kertesz). Although the fly larvae can wipe out snail populations, the particular circumstances existing in South Australia suggest that this native species is unlikely to be a useful biological control agent. However, the practical importance of flies as predators on snails in irrigation areas should not be discarded.


2004 ◽  
Vol 31 (2) ◽  
pp. 183 ◽  
Author(s):  
G. Story ◽  
D. Berman ◽  
R. Palmer ◽  
J. Scanlan

Rabbit haemorrhagic disease virus (RHDV) escaped from quarantine facilities on Wardang Island in September 1995 and spread through South Australia to Queensland by December 1995. To determine the impact of this biological control agent on wild rabbit populations in Queensland, shot sample and spotlight count data were collected at six sites. RHDV spread across Queensland from the south-west to the east at a rate of at least 91 km month–1 between October 1995 and October 1996. The initial impact on rabbit density appeared highly variable, with an increase of 81% (255 ± 79 (s.e.) to 385 ± 73 rabbits km–2) at one site and a decrease of 83% (129 ± 27 to 22 ± 18 rabbits km–2) at another during the first outbreak. However, after 30 months of RHDV activity, counts were at least 90% below counts conducted before RHDV arrived. Using a population model to account for environmental conditions, the mean suppression of rabbit density caused by rabbit haemorrhagic disease (RHD) was estimated to be 74% (ranging from 43% to 94% between sites). No outbreaks were observed when the density of susceptible rabbits was lower than 12 km–2. Where rabbit density remains low for long periods RHDV may not persist. This is perhaps most likely to occur in the isolated populations towards the northern edge of the range of rabbits in Australia. RHDV may have to be reintroduced into these populations. Further south in areas more suitable for rabbits, RHDV is more likely to persist, resulting in a high density of immune rabbits. In such areas conventional control techniques may be more important to enhance the influence of RHD.


1999 ◽  
Vol 47 (3) ◽  
pp. 307 ◽  
Author(s):  
John L. Read

Three sympatric diplodactyline geckos were studied in chenopod shrubland over a six-year period in northern South Australia. Females of each species were significantly larger than males. Rhynchoedura ornata and Diplodactylus conspicillatus, both termite specialists, consistently produced multiple clutches of two eggs in a long breeding season each year, whereas the reproductive output of D. stenodactylus, a dietary generalist, was more erratic. Females of the two Diplodactylus species bred in three consecutive years, whilst R. ornata seldom lived for more than two years. Mean relocation distances ranged from 26 to 35 m, which suggests that some individuals of all species maintained home ranges. However, many individuals of each species, especially R. ornata, were apparently transitory over areas greater than the 1-ha study site.


2015 ◽  
Vol 63 (4) ◽  
pp. 258 ◽  
Author(s):  
Matt W. Hayward ◽  
Aline Si Lin Poh ◽  
Jennifer Cathcart ◽  
Chris Churcher ◽  
Jos Bentley ◽  
...  

Despite a vigorous reintroduction program between 1985 and 2010, numbat populations in Western Australia are either static or declining. This study aimed to document the population ecology of numbats at two sites that are going against this trend: Scotia Sanctuary in far western New South Wales and Yookamurra Sanctuary in the riverland of South Australia. Scotia (64 659 ha) and Yookamurra (5026 ha) are conservation reserves owned and managed by the Australian Wildlife Conservancy and where numbats were reintroduced in 1999 and 1993 respectively. Both sites have large conservation-fence-protected introduced-species-free areas where there are no cats (Felis catus) or red foxes (Vulpes vulpes). Numbats were sourced from both wild and captive populations. From small founder populations, the Scotia numbats are now estimated to number 169 (113–225) with 44 at Yookamurra. Radio-collared individuals at Scotia were active between 13 and 31°C. Females had home ranges of 28.3 ± 6.8 ha and males 96.6 ± 18.2 ha, which leads to an estimated sustainable population or carrying capacity of 413–502 at Scotia. Captive-bred animals from Perth Zoo had a high mortality rate upon reintroduction at Scotia due to predation by raptors and starvation. The habitat preferences for mallee with a shrub understorey appear to be driven by availability of termites, and other reintroduced ecosystem engineers appear to have been facilitators by creating new refuge burrows for numbats. This study shows that numbats can be successfully reintroduced into areas of their former range if protected from introduced predators, and illustrates the difficulties in monitoring such cryptic species.


1999 ◽  
Vol 26 (4) ◽  
pp. 453 ◽  
Author(s):  
J. Read ◽  
P. Copley ◽  
P. Bird

Recent surveys have shown that the desert mouse (Pseudomys desertor), which was once considered to be rare in South Australia, is relatively widespread throughout the north-west of the State. However, historical localities in the Flinders Ranges and Nullarbor Plain were not matched with contemporary records, suggesting a range contraction to the central desert regions. Habitat preferences were determined from 78 captures at 41 sites, which revealed that samphire, sedge and nitrebush habitats, along with spinifex grassland, were favoured. A high tolerance to high rabbit numbers, mining activity, moderate cattle grazing pressures and cohabitation with Mus domesticus was evident. Pseudomys desertor is sometimes diurnal, possibly as a result of the time-consuming and regular foraging requirements of its folivorous diet. High mortality rates, resulting from prolonged exposure to predators, and lack of complex deep burrow systems are offset by its high fecundity and ecological plasticity. We consider that P. desertor is secure in the north-western arid zone of South Australia.


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