Trophic rewilding of native extirpated predators on Bass Strait Islands could benefit woodland birds

Fielding, Matthew W.; Buettel, Jessie C.; Brook, Barry W.

doi:10.1080/01584197.2020.1797509

Cited by 6 publications

(10 citation statements)

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“…The roadkill effect was amplified on the island routes where roadside carrion was a predictor of raven presence across the entire year, except for summer on some routes (Figure 5). Habitat loss on the Bass Strait islands combined with extensive hunting by Europeans has resulted in the extirpation of several predators on the islands, such as the spotted‐tailed quoll Dasyurus maculatus and wedge‐tailed eagle Aquila audax (Fielding, Buettel, & Brook, 2020; Peacock et al., 2018; Threatened Species Section, 2012). The loss of these carnivores from the Bass Strait islands could mean that the remaining scavengers, such as ravens, have less competition for resources and subsequently greater access to carrion.…”

Section: Discussionmentioning

confidence: 99%

“…For example, in north‐east Tasmania, where Tasmanian devils Sarcophilus harrisii have declined due to devil‐facial‐tumour disease, feral cats Felis catus and forest ravens Corvus tasmanicus have increased in abundance due to increased access to carrion and spotted‐tailed quolls Dasyurus maculatus have increased their scavenging efforts due to competitive release (Cunningham et al., 2018). In the Bass Strait, land‐use change on the islands has led to the recent (19th–20th Century) extirpation of the native mammalian predators, such as quolls, and the loss of the wedge‐tailed eagle Aquila audax on King Island (Fielding, Buettel, & Brook, 2020; Peacock et al., 2018). Therefore, the surviving mesopredators could have greater access to carrion, leading to increased abundance and unbalance within the community structure relative to that elsewhere in Tasmania.…”

Section: Introductionmentioning

confidence: 99%

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Roadkill islands: Carnivore extinction shifts seasonal use of roadside carrion by generalist avian scavenger

Fielding

Buettel

Brook

et al. 2021

Journal of Animal Ecology

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1. Global road networks facilitate habitat modification and are integral to human expansion. Many animals, particularly scavengers, use roads as they provide a reliable source of food, such as carrion left after vehicle collisions. Tasmania is often cited as the 'roadkill capital of Australia', with the isolated offshore islands in the Bass Strait experiencing similar, if not higher, levels of roadkill. However, native mammalian predators on the islands are extirpated, meaning the remaining scavengers are likely to experience lower interference competition.2. In this study, we used a naturally occurring experiment to examine how the loss of mammalian carnivores within a community impacts roadside foraging behaviour by avian scavengers.3. We monitored the locations of roadkill and forest ravens Corvus tasmanicus, an abundant scavenger species, on eight road transects across the Tasmanian mainland (high scavenging competition) and the Bass Strait islands (low scavenging competition). We represented raven observations as one-dimensional point patterns, using hierarchical Bayesian models to investigate the dependence of raven spatial intensity on habitat, season, distance to roadkill and route location. 4. We found that roadkill carcasses were a strong predictor of raven presence along road networks. The effect of roadkill was amplified on roads on the Bass Strait islands, where roadside carrion was a predictor of raven presence across the entire year. In contrast, ravens were more often associated with roadkill on Tasmanian mainland roads in the autumn, when other resources were low. This suggests that in the absence of competing mammalian scavengers, ravens choose to feed on roadside carrion throughout the year, even in seasons when other resources are available. This lack of competition could be disproportionately benefiting forest ravens, leading to augmented raven populations and changes to the vertebrate community structure. 5.Our study provides evidence that scavengers modify their behaviour in response to reduced scavenger species diversity, potentially triggering trophic shifts and highlighting the importance of conserving or reintroducing carnivores within ecosystems.

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Section: Discussionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Roadkill islands: Carnivore extinction shifts seasonal use of roadside carrion by generalist avian scavenger

Fielding

Buettel

Brook

et al. 2021

Journal of Animal Ecology

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“…However, these population shifts, and the associated consequences, require further investigation. Regardless, the results of this study highlight the importance of conservation intervention in these circumstances, such as the targeted management of roadside carrion (e.g., removal of carcasses or vehicle speed reduction) and/or the reintroduction of the recently extirpated native scavengers (Fielding, Buettel & Brook 2020). As we are faced with the escalating threat of further extinctions across the world, our study highlights the significance of conserving scavenger diversity within an ecosystem.…”

Section: Discussionmentioning

confidence: 84%

“…This loss of habitat combined with extensive hunting by Europeans has resulted in the extirpation of several predators on the islands. Both eastern ( Dasyurus viverrinus ) and spotted-tailed quolls ( Dasyurus maculatus ) were hunted to extinction on King and Flinders Islands and a major avian scavenger, the wedge-tailed eagle ( Aquila audax ), is now a rare visitor to King Island (Peacock et al 2018; Fielding, Buettel & Brook 2020). Remains of the Tasmanian devil ( Sarcophilus harrisii ) have been found in cave deposits on Flinders Island, dated at roughly 4,000 years ago, but it is unclear whether they were present when Europeans arrived, and there is no fossil evidence of the species on King Island (Hope 1973).…”

Section: Discussionmentioning

confidence: 99%

“…Due to this high density, roadkill is a common sight, and farmers will often shoot the macropods en masse under crop-protection permits, leaving the bodies where they fall (Threatened Species Section 2012). Furthermore, land-use change on the islands has led to the recent (19 th – 20 th Century) extirpation of mammalian predators, such as quolls ( Dasyurus maculatus and Dasyurus viverrinus ), and the loss of the wedge-tailed eagle ( Aquila audax ) on King Island (Peacock et al 2018; Fielding, Buettel & Brook 2020).…”

Section: Introductionmentioning

confidence: 99%

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Roadkill islands: carnivore extinction shifts seasonal use of roadside carrion by generalist avian scavenger

Fielding¹,

Buettel²,

Brook³

et al. 2021

Preprint

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Global road networks facilitate habitat modification and are integral to human expansion. Many animals, particularly scavengers, use roads as they provide a reliable source of food, such as carrion left after vehicle collisions. Tasmania is often cited as the 'roadkill capital of Australia', with the isolated offshore islands in the Bass Strait experiencing similar, if not higher, levels of roadkill. However, native mammalian predators on the islands are extirpated, meaning the remaining scavengers are likely to experience lower interference competition. In this study, we use a naturally occurring experiment to examine how the loss of mammalian carnivores within a community impacts roadside foraging behaviour by avian scavengers. We monitored the locations of roadkill and forest ravens (Corvus tasmanicus), an abundant scavenger species, on eight road transects across the Tasmanian mainland (high scavenging competition) and the Bass Strait islands (low scavenging competition). We represented raven observations as one-dimensional point patterns, using hierarchical Bayesian models to investigate the dependence of raven spatial intensity on habitat, season, distance to roadkill and route location. We found that roadkill carcasses were a strong predictor of raven presence along road networks. The effect of roadkill was amplified on roads on the Bass Strait islands, where roadside carrion was a predictor of raven presence across the entire year. In contrast, ravens were more often associated with roadkill on Tasmanian mainland roads in the autumn, when other resources were low. This suggests that in the absence of competing mammalian scavengers, ravens choose to feed on roadside carrion throughout the year, even in seasons when other resources are available. This low interference competition could be disproportionately benefiting forest ravens, leading to augmented raven populations and changes to the vertebrate community structure. Our study provides evidence that scavengers modify their behaviour in response to reduced scavenger species diversity, potentially triggering trophic shifts and highlighting the importance of conserving or reintroducing carnivores within ecosystems.

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Species distribution models for conservation: Identifying translocation sites for eastern quolls under climate change

Barlow

Johnson

McDowell

et al. 2021

Global Ecology and Conservation

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Trophic rewilding of native extirpated predators on Bass Strait Islands could benefit woodland birds

Cited by 6 publications

References 5 publications

Roadkill islands: Carnivore extinction shifts seasonal use of roadside carrion by generalist avian scavenger

Roadkill islands: Carnivore extinction shifts seasonal use of roadside carrion by generalist avian scavenger

Roadkill islands: carnivore extinction shifts seasonal use of roadside carrion by generalist avian scavenger

Species distribution models for conservation: Identifying translocation sites for eastern quolls under climate change

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