Introduction to the special edition on overabundant macropods

Read, John; Wilson, George R.; Coulson, Geoff; Radford, James Q.

doi:10.1111/emr.12494

Cited by 6 publications

(4 citation statements)

References 37 publications

(32 reference statements)

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“…This overpopulation caused severe vegetation browsing of some plant species and a starvation‐induced population crash during drought. Macropods are herbivores and are commonly linked to problems of overabundance and overgrazing when predation pressure is low (Coulson & Eldridge, 2010; Read et al., 2021), including during reintroductions (burrowing bettongs [Hayward et al., 2010; Treloar et al., 2021]; brush‐tailed bettongs [ Bettongia penicillata ] [Short, 2009]; tammar wallabies [ Macropus eugenii ]; grey kangaroos [ Macropus giganteus ] [Copley, 1994]). These species often undergo a characteristic pattern of growth after release, which includes a latent establishment phase, an exponential increase phase, and a significant decline or “crash” phase followed by a more consistent and lower population level.…”

Section: Discussionmentioning

confidence: 99%

Influence of interactive effects on long‐term population trajectories in multispecies reintroductions

Moseby,

Read,

Tuft

et al. 2024

Conservation Biology

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Reintroduced populations are typically considered to progress through establishment, growth and regulatory phases. However, most reintroduction programs don't monitor intensively enough to test this conceptual model. We studied population indices derived from track activity of four IUCN‐listed species (greater bilby, burrowing bettong, greater stick‐nest rat and Shark Bay bandicoot) over 23 years after multiple reintroductions of each species in arid Australia. We compared population trajectories between species, and investigated the effect of time and environmental variables. All species bred immediately after release and the growth phase lasted between 3 and 16 years, varying markedly between but not within species. The end of the growth phase was characterised by an obvious peak in population density followed by either a catastrophic decline and sustained low density (bettongs), a slow decline to extinction after 20 years (stick‐nest rat), or a slight decline followed by irregular fluctuations in density (bilby and bandicoot). Minor fluctuations were related to environmental variables such as 12 month cumulative rainfall and lagged summer maximum temperatures. Three of the four species did not reach a regulation phase, even after 23 years, possibly due to interspecific competition and trophic cascades triggered by predator removal and multi‐species reintroductions. Bilbies and bandicoots exhibited a second growth phase 18 years after reintroduction, likely caused by high rainfall and increased resources following the population crash of overabundant bettongs. Our results suggest that assemblages within multi‐species reintroductions demonstrate high variability in population trajectories due to interactive effects. Intensive monitoring to assess population viability may require decades, particularly where multiple species are reintroduced, release sites are confined and where the climate is unpredictable. Intensive monitoring also allows for adaptive management to prevent precipitous population declines. Practitioners should not assume reintroduced species pass through predictable post‐release population phases or that viability is assured after a certain time period.This article is protected by copyright. All rights reserved

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Section: Discussionmentioning

confidence: 99%

Influence of interactive effects on long‐term population trajectories in multispecies reintroductions

Moseby,

Read,

Tuft

et al. 2024

Conservation Biology

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“…Throughout much of the Australian southern rangelands, kangaroos are harvested commercially for meat and leather. The primary goal of the industry is to provide kangaroo products to consumers, but ecologicallysustainable commercial harvest of kangaroos also provides an alternative management approach to reducing the damage caused by over overgrazing (Grigg 1987;Read et al 2021). Conservative harvest quotas have been in place to allay concerns regarding the exploitation of kangaroos.…”

Section: Land Use and Managementmentioning

confidence: 99%

“…Conservative harvest quotas have been in place to allay concerns regarding the exploitation of kangaroos. As a result, after 40 years of monitoring, there is no evidence that commercial kangaroo harvest threatens populations of the 4 harvested species (Ampt & Baumber 2006;Lunney et al 2018;Read et al 2021).…”

Section: Land Use and Managementmentioning

confidence: 99%

Land use and dingo baiting are correlated with the density of kangaroos in rangeland systems

Dawson

Kreplins²,

Kennedy

et al. 2022

Integr. Zool.

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Rangelands worldwide have been subject to broadscale modification, such as widespread predator control, introduction of permanent livestock water and altered vegetation to improve grazing. In Australia, these landscape changes have resulted in kangaroos (i.e. large macropods) populations increasing over the past 200 years. Kangaroos are a key contributor to total grazing pressure and in conjunction with livestock and feral herbivores have been linked to land degradation. We used 22 years of aerial survey data to investigate whether the density of 3 macropod species in the southern rangelands of Western Australia was associated with: (i) land use, including type of livestock, total livestock, density of feral goats, type of land tenure, and kangaroo commercial harvest effort; (ii) predator management, including permitted dingo control effort, estimated dingo abundance, and presence of the State Barrier Fence (a dingo exclusion fence); and (iii) environmental variables: ruggedness, rainfall, fractional cover, and total standing dry matter. Red kangaroos (Osphranter rufus) were most abundant in flat, open vegetation, on pastoral land, where area permitted for dingo control was high, and numbers were positively associated with antecedent rainfall with a 12‐month delay. Western grey kangaroos (Macropus fuliginosus) were most abundant on flat, agricultural land, but less abundant in areas with high permitted dingo control. Euros (Osphranter robustus) were most abundant in rugged pastoral land with open vegetation, where permitted dingo control was high. While environmental variables are key drivers of landscape productivity and kangaroo populations, anthropogenic factors such as land use and permitted dingo control are strongly associated with kangaroo abundance.

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“…are iconic wildlife species and are common and widespread in Australia. They can be overabundant in many situations, resulting in negative impacts on biodiversity values, agricultural production, human health and amenity, as well as welfare of the kangaroos themselves (Coulson 2001(Coulson , 2007Descovich et al 2016;Read et al 2021). While the need for kangaroo management is generally understood by the Australian public, the acceptability of lethal control varies widely across Australian society, farmers being the mostly likely to support kangaroo culling (Sinclair et al 2019;van Eeden et al 2019;Drijfhout et al 2020;Boulet et al 2021).…”

Section: Introductionmentioning

confidence: 99%

Implementing implants: delivery efficiency, contraceptive efficacy and population outcomes in two overabundant kangaroo populations

Coulson

Wilson

2023

Wildlife Res.

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Context Overabundant native wildlife can pose serious challenges for managers. The most direct, immediate way to reduce density-dependent impacts is by culling, but lethal control often lacks public support. Fertility control offers a non-lethal management alternative. Aims We conducted two fertility-control projects on eastern grey kangaroos (Macropus giganteus), a common and widespread species in Australia. We aimed to evaluate three key components of an integrated fertility-control project, namely, delivery efficiency, contraceptive efficacy and population-level outcomes. Methods The two study sites on the urban fringe of Melbourne, Australia, were small reserves. Both had undergone an irruptive peak and subsequent crash, with negative impacts on animal health. Gresswell Forest (52 ha) is open forest habitat enclosed by a kangaroo-proof fence. Serendip Sanctuary (250 ha) is grassy woodland and retired pasture, with a boundary allowing kangaroo movement onto neighbouring properties. We captured kangaroos with a dart gun at night and treated all healthy adult females with subdermal levonorgestrel implants. Key results Delivery efficiency (catch-per-unit effort) was greater from a vehicle at Serendip Sanctuary than on foot at Gresswell Forest, with only a marginal decline over successive nights at both sites. Background fecundity was 91% at Serendip Sanctuary, but close to zero at Gresswell Forest. Treatment efficacy was high, being 86–100% infertility at Serendip Sanctuary and 96–100% at Gresswell Forest. At Serendip Sanctuary, the proportion of females treated never reached 75%, whereas only one female at Gresswell Forest remained untreated after 3 years. Population density at Serendip Sanctuary exceeded the target range 3 years after culling and fertility control. No culling occurred at Gresswell Forest, but fertility control apparently held population density at a moderate level, albeit much higher than the density target. Conclusions Future management at Serendip Sanctuary and Gresswell Forest will require a sustained fertility-control effort. Further culling may also be required to complement fertility control at Serendip Sanctuary, the larger, open site. Implications Contraceptive efficacy of levonorgestrel is high in kangaroos and implants can be delivered efficiently, but achieving control of a large, open population will be challenging.

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Introduction to the special edition on overabundant macropods

Cited by 6 publications

References 37 publications

Influence of interactive effects on long‐term population trajectories in multispecies reintroductions

Influence of interactive effects on long‐term population trajectories in multispecies reintroductions

Land use and dingo baiting are correlated with the density of kangaroos in rangeland systems

Implementing implants: delivery efficiency, contraceptive efficacy and population outcomes in two overabundant kangaroo populations

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