Measuring Home‐Range Changes Following Density Reduction of Australian Brushtail Possum

Margetts, Belinda I.; Ross, James G.; Buckley, Hannah

doi:10.1002/jwmg.21768

Cited by 6 publications

(8 citation statements)

References 40 publications

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“…In TA#2, pre-feed baits were sown at 1 kg ha −1 , with a 10% sowing overlap for both pre-feed applications, and toxic baits containing 0.15% 1080 were sown at 2 kg ha −1 , with a 50% sowing overlap (Table 1). The reduction in bait quantity for TA#2 and its pre-feeds was in recognition that, with many fewer predators present, home ranges may increase (Margetts et al 2020). Caching of baits by predators during prefeed would be undesirable if it meant that toxic baits were not consumed.…”

Section: Treatmentmentioning

confidence: 99%

Dual aerial 1080 baiting operation removes predators at a large spatial scale

Nichols¹,

Ltd²,

Wellington³

et al. 2021

NZJE

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As New Zealand attempts to become predator free by 2050, transitioning aerial 1080 (sodium fluoroacetate) operations from predator control to complete predator removal has become an important research objective. Aerial 1080 operations may not remove every last target animal, but they may be able to remove a very high proportion (> 0.99). We trialled a modified [dual] aerial 1080 operation for the removal of brushtail possums (Trichosurus vulpecula), ship rats (Rattus rattus), and stoats (Mustela erminea) at large spatial scale. Our trial involved two toxin applications (TA#1 & TA#2), each preceded by two applications of non-toxic pre-feed bait. Different types of cereal baits and lures were used for each toxin application. Camera traps (n = 142; 200-1431 m asl) were used to detect the target species and to incidentally observe house mouse (Mus musculus), birds, and ungulates across the study area. The operation had no significant impact on the number of cameras detecting most birds and ungulate species; however, house mouse, blackbird (Turdus merula), and red deer (Cervus elaphus) were detected on significantly fewer cameras after TA#1 than before. Numbers of cameras that detected target species were significantly reduced for all three target species after TA#1, and significantly reduced again for possums after TA#2, when no stoats were detected on cameras and a small number of cameras detected rats. Mean relative abundance estimates based on camera trap indices (proportion of camera trap days that target species were detected) showed the operation appears to have removed over 99% of ship rats, stoats, and possums.

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Section: Treatmentmentioning

confidence: 99%

Dual aerial 1080 baiting operation removes predators at a large spatial scale

Nichols¹,

Ltd²,

Wellington³

et al. 2021

NZJE

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“…Interestingly, according to the final density model, rat movement patterns did not change with the application of 1080 or across the wide range of densities observed. In other mammal species, home range is known to change with density [50]. Black rats are known to display varying home ranges between sites, although it is unclear to what extent this is an influence of density or food abundance [51,52].…”

Section: Discussionmentioning

confidence: 99%

Assessing Two Different Aerial Toxin Treatments for the Management of Invasive Rats

O’Malley

Stanley

Russell

2022

Animals

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Aotearoa–New Zealand has embarked on an ambitious goal: to completely eradicate key invasive mammals by 2050. This will require novel tools capable of eliminating pests on a large scale. In New Zealand, large-scale pest suppression is typically carried out using aerial application of the toxin sodium fluoroacetate (1080). However, as currently applied, this tool does not remove all individuals. A novel application method, dubbed ‘1080-to-zero’, aims to change this and reduce the abundances of target pests to zero or near-zero. One such target is black rats (Rattus rattus), an invasive species challenging to control using ground-based methods. This study monitored and compared the response of black rats to a 1080-to-zero operation and a standard suppression 1080 operation. No difference in the efficacy of rat removal was found between the two treatments. The 1080-to-zero operation did not achieve its goal of rat elimination or reduction to near-zero levels, with an estimated 1540 rats surviving across the 2200 ha treatment area. However, 1080 operations can produce variable responses, and the results observed here differ from the only other reported 1080-to-zero operation. We encourage further research into this tool, including how factors such as ecosystem type, mast fruiting and operational timing influence success.

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“…Possum home range size varies between high-density and low-density populations, with low density populations generally exhibiting larger home ranges (Whyte et al 2013;Richardson 2017). After control, previously high-density populations are more likely to exhibit movement behaviour described as home range expansion (Rouco et al 2017;Margetts et al 2020) or the vacuum effect (Clinchy 1999), particularly in the absence of landscape constraints (Brockie et al 1997;Efford et al 2000;Pech et al 2010). These changes have been observed to occur within a few weeks of control (Margetts et al 2020).…”

Section: Introductionmentioning

confidence: 99%

Rivers as obstacles to home range expansion by the brushtail possum

Cook¹,

Wellington²,

Mulgan³

et al. 2021

NZJE

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Strategies for defending large tracts of land from mammalian pest incursion are urgently needed. We report on a study investigating whether brushtail possum (Trichosurus vulpecula) range expansion into a controlled area was restricted by a watercourse. The true left of the Orongorongo River valley was treated with 1080 poison baits, and a 250 ha area bordering the river on the true right was excluded from treatment. Nontoxic cereal bait containing pyranine biomarker was sown repeatedly over half of the excluded area for nine weeks after poisoning. Traps installed on the true left of the river caught no marked possums. This outcome suggests that the river acted as an obstacle to possum movement, specifically, home range expansion into an area of low conspecific density. Our study contributes to the body of evidence that watercourses can inhibit possum movement, supporting operational practice that aligns eradication boundaries with rivers to slow the rate of possum reinvasion.

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Measuring Home‐Range Changes Following Density Reduction of Australian Brushtail Possum

Cited by 6 publications

References 40 publications

Dual aerial 1080 baiting operation removes predators at a large spatial scale

Dual aerial 1080 baiting operation removes predators at a large spatial scale

Assessing Two Different Aerial Toxin Treatments for the Management of Invasive Rats

Rivers as obstacles to home range expansion by the brushtail possum

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