Vegetation damage caused by high densities of burrowing bettongs (Bettongia lesueur) at Arid Recovery

Linley, Grant D.; Moseby, Katherine E.; Paton, David C.

doi:10.1071/am15040

Cited by 27 publications

(36 citation statements)

References 32 publications

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“…Populations with defined boundaries such as islands or enclosures are unable to migrate to new areas, and may overexploit their surrounding environment (Linley et al . ). Larger body size may be beneficial to survival and reproduction when resources are abundant, but when resources decline, large animals rapidly lose body condition (Moss & Croft ).…”

Section: Discussionmentioning

confidence: 97%

Environmental determination of body size in mammals: Rethinking ‘island dwarfism’ in the golden bandicoot

Dunlop

Morris

2018

Austral Ecology

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There are several cases of insular animal species exhibiting dramatic differences in body size when compared with mainland counterparts. Such pronounced morphological changes can arise from divergent selection via differing resource availability, competition or predation pressure. Past studies have not been able to demonstrate a reversal of these morphological changes when populations are removed from their island situation. This study examines the body size response of populations of the Barrow Island 'dwarf' subspecies of golden bandicoot (Isoodon auratus barrowensis: Ramsay, 1887) following translocation to an island and mainland site within their former range. Skeletal and mass measurements, body condition and fecundity of released animals and their offspring were compared to data from the source population. When comparing bandicoots born at translocation sites to source populations, males were significantly larger in skeletal size and mass, females were also significantly larger and exhibited higher reproductive output (number, frequency and average mass of pouch young). These effects occurred in a gradient according to environmental conditions, where animals were smallest and least productive at the densely populated source site, larger and more productive on a nearby island, and largest and most productive at a mainland site with some nutritional supplementation. These changes in skeletal size, mass and fecundity took place in the first 1-4 generations (18 months post-release), suggesting that the response is not explained by natural selection. We posit that the small size of golden bandicoots on Barrow Island (315.8 AE 4.2 g, this study, cf 569.4 AE 19.3 g, mainland) is not a genotypic response to selective pressures, but rather a reversible phenotypic response to more favourable environmental conditions. A reduction in competitive pressures appeared to allow bandicoots to grow to a larger size and mass, and allow greater reproductive output. Ecological processes relating to resource limitation appear to drive 'island dwarfism' in I. auratus, and may apply to other insular species with morphological differentiation.

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Section: Discussionmentioning

confidence: 97%

Environmental determination of body size in mammals: Rethinking ‘island dwarfism’ in the golden bandicoot

Dunlop

Morris

2018

Austral Ecology

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“…For example, with the removal of cats and foxes, herbivorous prey species may increase in density, with this having direct consequences for vegetation communities (possibly leading to changes in species composition and structure: e.g. Linley et al ). In turn, changes in vegetation are likely to influence the availability of habitat and/or food for a range of fauna (as occurred when key herbivore populations were impacted by the reintroduction of wolves to Yellowstone National Park; Ripple & Beschta ).…”

Section: Introductionmentioning

confidence: 99%

The impact of a fox‐ and cat‐free safe haven on the bird fauna of remnant vegetation in southwestern Australia

Smith

Ruykys

Palmer

et al. 2020

Restoration Ecology

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Introduced predators are a serious threat to Australian vertebrates. However, the consequences of predation for an area's avifauna have rarely been quantified. We took advantage of the establishment of a 7,832 ha fox‐ and cat‐free safe haven at Mt Gibson, in Western Australia, to assess the consequences of excluding introduced mammal predators on the bird fauna. Bird surveys were conducted over 6 years, before and after the establishment of the introduced predator‐free safe haven. After 3 years, half the sites were enclosed by the fence that excluded introduced predators, while the remainder of sites remained outside the fence and were exposed to fox and cat activity. The sites were stratified by four major vegetation types. A total of 91 bird species were variously detectable with the survey approach, but were typically more detectable during morning surveys. Site occupancy varied considerably among species, but overall, occupancy by all species was most likely to be either not impacted or positively impacted by the safe haven. The most notable change was that avifaunal richness appeared to increase in woodland and shrubland habitats within, as compared to outside, the safe haven. We conclude that: (1) the safe haven had an overall positive impact on bird occupancy; and (2) there were no consistent trends with respect to the kinds of species whose occupancy was positively impacted, beyond them all being small‐ to medium‐sized birds and mostly insectivorous. However, these conclusions must be tempered by the poor detection probability of many species.

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“…The elevated population densities of burrowing bettongs within the Arid Recovery Reserve has resulted in vegetation damage (Linley et al . ; Moseby et al . ).…”

Section: Discussionmentioning

confidence: 99%

One‐way gates successfully facilitate the movement of burrowing bettongs (Bettongia lesueur) through exclusion fences around reserve

2018

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When native herbivores are enclosed in fenced reserves without predators or dispersal options then overgrazing can occur, leading to damage to vegetation and co-occurring fauna species. One-way gates that allow medium-sized herbivores to exit fenced reserves may be an effective management tool to address overabundance or facilitate population expansion. We tested the use of one-way gates to facilitate the movement of the reintroduced burrowing bettong (Bettongia lesueur) from inside to outside a fenced reserve in arid South Australia. Oneway gates were installed in the exterior fence of the reserve and assessed using remote motion-sensor cameras. The influence of gate position (dune, swale or corner) and provision of food were assessed in relation to gate visits and exits. Animals were trapped inside and outside the gates to determine any population bias in gate exits. Baited gates recorded significantly more exits than unbaited gates and dune gates had higher exit rates than interdunal swale gates. When gates were unbaited, those installed in corners of the reserve showed significantly higher visitation by bettongs and a non-significant trend towards more exits compared to gates placed in straight sections of fence along dunes or swales. There was no sex or age bias of burrowing bettongs using the gates and bettongs travelled between 75 m and 1535 m from their warrens to use the gates. No non-target species gained access to the reserve through the one-way gates and only two non-target animals used the gates to exit the reserve confirming gate specificity for bettongs. During the same period, 96 burrowing bettongs exited the reserve through the one-way gates. One-way gates may be a management strategy for facilitating passive movement of medium-sized herbivores outside of fenced reserves for the purposes of reducing overpopulation or facilitating population expansion outside reserves.One-way gates were based on a combination of two gate designs tested during pen trials by Crisp and Moseby

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Vegetation damage caused by high densities of burrowing bettongs (Bettongia lesueur) at Arid Recovery

Cited by 27 publications

References 32 publications

Environmental determination of body size in mammals: Rethinking ‘island dwarfism’ in the golden bandicoot

Environmental determination of body size in mammals: Rethinking ‘island dwarfism’ in the golden bandicoot

The impact of a fox‐ and cat‐free safe haven on the bird fauna of remnant vegetation in southwestern Australia

One‐way gates successfully facilitate the movement of burrowing bettongs (Bettongia lesueur) through exclusion fences around reserve

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