ArticlePublisher preview available

An outback oasis: the ecological importance of bilby burrows

Journal of Zoology

March 2019
308(3)

DOI:10.1111/jzo.12663

Authors:

Stuart Dawson

Murdoch University

Peter J Adams

Department of Primary Industries and Regional Development, WA

Katherine E. Moseby

UNSW Sydney

Show all 8 authorsHide

Ecosystem engineers are species that have a role in creating and maintaining certain habitat traits that are important for other species. Burrowing species do this by creating subterranean refugia from predation and thermal extremes, but also providing foraging opportunities through soil movement and by increasing local landscape heterogeneity. In this study, we used camera traps to monitor the burrows of greater bilbies (Macrotis lagotis), a vulnerable Australian marsupial, in an area subject to frequent disturbance by fire. We tested the hypothesis that bilby burrows provide refuge for other species and therefore their presence increases biodiversity. In total, 45 taxa – 22 bird, 16 reptile and 7 mammal taxa – were recorded interacting with 127 burrows across 7 sites. Species richness was greater at burrows compared with vegetation away from burrows, while abundance was no different. There was no difference in species assemblage for bilby burrows that were actively maintained by bilbies compared with abandoned burrows, although there was more activity at bilby maintained burrows. A wildfire allowed us to test the ad hoc hypothesis that the use of bilby burrows was greater when vegetation cover was removed by fire. We recorded significant differences in species assemblage interacting with burrows after fire, although overall species richness and abundance did not change. The response of individual species was variable; for example, burrows provide a refuge for smaller species (such as mice and small reptiles), and may therefore protect them from the effects of fire. Where they persist, bilbies provide an important ecosystem engineering service, as their burrows support a broad range of species. Further reduction in the distribution of the bilby is therefore likely to have a flow‐on effect on biodiversity, impacting species that use their burrows for refuge.

‘Grass‐seed’ population, showing all burrows located during monitoring, as well as those that were monitored by camera, and the location of control cameras. [Colour figure can be viewed at zslpublications.onlinelibrary.wiley.com]

…

Example photos of a selection of the taxa recorded interacting with burrows. (a) Macrotis lagotis, (b) Varanus panoptes, (c) Pseudomys spp., (d) Pardalotus rubricatus, (e) Rhipidura leucophrys, (f) Pomatostomus temporalis, (g) Felis catus, (h) Canis familiaris, (i) Pogona minor. [Colour figure can be viewed at zslpublications.onlinelibrary.wiley.com]

…

Species richness estimates calculated using individual‐based extrapolation (left column), and individual based rarefaction, giving an asymptotic species richness estimate (right column). 95% confidence intervals are used throughout, and data is extrapolated to three times the original sample size. (a) The species richness is likely to be greater at burrow sites, however the 95% confidence intervals overlap due to high variation at control cameras. (b) The species richness does not change after fire. (c) The species richness is greater at maintained burrows than abandoned burrows.

…

Community composition for taxa interacting with bilby burrows, each datum point represents a single burrow or control site monitored by camera trap. Datum points close to each other have similar communities, and the level of overlap between groups shows the level of similarity between treatments/populations, the significance of which is tested using an ANOSIM. Stress values are shown in the bottom left corner. (a) The species assemblage at unburnt burrows and unburnt control camera stations at the Grass‐seed population were significantly different. Similarly, unburnt burrows and burnt burrows had the same assemblage, while the assemblage at control sites changed significantly after fire. (b) The community assemblage at maintained burrows was not different from abandoned burrows. [Colour figure can be viewed at zslpublications.onlinelibrary.wiley.com]

…

Trap rate (capture per day) of the 6 most common taxa at the ‘Grass‐seed’ site, across all burrows, before and after fire. Difference in species trap rate between burrows and control stations is compared using only the black bars.

…

Figures - available from: Journal of Zoology

This content is subject to copyright. Terms and conditions apply.

A preview of this full-text is provided by Wiley.

Learn more

Content available from Journal of Zoology

This content is subject to copyright. Terms and conditions apply.

An outback oasis: the ecological importance of

bilby burrows

S. J. Dawson

, L. Broussard

, P. J. Adams

1,3

, K. E. Moseby

, K. I. Waddington

, H. T. Kobryn

P. W. Bateman

& P. A. Fleming

1 Environmental and Conservation Sciences, School of Veterinary and Life Sciences, Murdoch University, Murdoch, WA, Australia

2 Department of Ecology and Evolutionary Biology, University of Colorado, Boulder, CO, USA

3 Invasive Species, Department of Primary Industries and Regional Development, South Perth, WA, Australia

4 School of Biological, Earth and Environmental Sciences, University of New South Wales, Sydney, NSW, Australia

5 Buru Energy, Perth, WA, Australia

6 School of Molecular and Life Sciences, Curtin University, Perth, WA, Australia

Keywords

commensal; ecosystem engineer; refuge;

Kimberley; burrows; wildﬁre; Macrotis lagotis.

Correspondence

Stuart J. Dawson, Environmental and

Conservation Sciences, School of Veterinary and

Life Sciences, Murdoch University, South Street

6069, Murdoch, WA 6150, Australia.

Email: stuart.dawson102@gmail.com

Editor: Matthew Hayward

Received 23 September 2018; revised 28

December 2018; accepted 6 February 2019

doi:10.1111/jzo.12663

Abstract

Ecosystem engineers are species that have a role in creating and maintaining cer-

tain habitat traits that are important for other species. Burrowing species do this by

creating subterranean refugia from predation and thermal extremes, but also provid-

ing foraging opportunities through soil movement and by increasing local landscape

heterogeneity. In this study, we used camera traps to monitor the burrows of

greater bilbies (Macrotis lagotis), a vulnerable Australian marsupial, in an area sub-

ject to frequent disturbance by ﬁre. We tested the hypothesis that bilby burrows

provide refuge for other species and therefore their presence increases biodiversity.

In total, 45 taxa –22 bird, 16 reptile and 7 mammal taxa –were recorded interact-

ing with 127 burrows across 7 sites. Species richness was greater at burrows com-

pared with vegetation away from burrows, while abundance was no different.

There was no difference in species assemblage for bilby burrows that were actively

maintained by bilbies compared with abandoned burrows, although there was more

activity at bilby maintained burrows. A wildﬁre allowed us to test the ad hoc

hypothesis that the use of bilby burrows was greater when vegetation cover was

removed by ﬁre. We recorded signiﬁcant differences in species assemblage interact-

ing with burrows after ﬁre, although overall species richness and abundance did

not change. The response of individual species was variable; for example, burrows

provide a refuge for smaller species (such as mice and small reptiles), and may

therefore protect them from the effects of ﬁre. Where they persist, bilbies provide

an important ecosystem engineering service, as their burrows support a broad range

of species. Further reduction in the distribution of the bilby is therefore likely to

have a ﬂow-on effect on biodiversity, impacting species that use their burrows for

refuge.

Introduction

Ecosystem engineers are animals that, through multiple pro-

cesses, modify the physical environment and in doing so create

and maintain habitat that beneﬁts other species (Jones et al.

1994; Jones, Lawton & Shachak, 1997; Jones et al. 2010).

Ecosystem engineers can create and maintain habitat by chang-

ing water ﬂows (Wright, Jones & Flecker, 2002), creating

microhabitats (Campos-Arceiz, 2009), modifying vegetation

structure (Valeix et al., 2011) or changing nutrient cycling

(James, Eldridge & Hill, 2009; Platt et al., 2016). Examples of

this diverse group include beavers (Castor canadensis) build-

ing dams (Wright et al., 2002; Bartel, Haddad & Wright,

2010), termites (Isoptera) creating refugia in colony mounds

(Dangerﬁeld, McCarthy & Ellery, 1998; Fleming & Loveridge,

2003; Jouquet et al., 2011), the shells of marine molluscs

(Mollusca) providing habitat heterogeneity in benthic environ-

ments (Gutierrez et al., 2003), and proboscideans changing the

structural complexity of vegetation by damaging trees and cre-

ating large and permanent game trails (Pringle, 2008; Haynes,

2012). All these taxa have marked effects on the surrounding

community (Jones et al., 1997; Wright & Jones, 2004).

In Australia, one of primary processes driven by ecosystem

engineers is the bioturbation of soil by digging mammals,

many of which have suffered signiﬁcant population and range

declines (James & Eldridge, 2007; Fleming et al., 2014).

Journal of Zoology 308 (2019) 149–163 ª2019 The Zoological Society of London 149

Journal of Zoology. Print ISSN 0952-8369

Rabbit warrens: an important resource for invasive alien species in semi-arid Australia

Article

Full-text available

Mar 2023

Context: The decline and extinction of native burrowing mammals across much of Australia has resulted in a loss of underground refugia constructed by native fauna in the environment. The introduced European rabbit (Oryctolagus cuniculus) is now the most widespread mammalian burrower across Australia. Rabbits are an invasive species in Australia, and the destruction of rabbit warrens for pest management is common practice. This destruction of warrens removes a potential refuge for both rabbits and other species in the environment. In landscapes where critical weight range burrowing mammals have declined, the widespread destruction of rabbit warrens removes many underground refuges for several commensal animal species. Aims: To identify the use of rabbit warrens by fauna in the seasonally hot, semi-arid Ikara-Flinders Ranges National Park (IFRNP) in South Australia. Methods: We used camera traps placed at burrow entrances of warrens and nearby structure to identify the vertebrate species that interact with rabbit warrens in the IFRNP. Key results: We recorded 11 bird, nine mammal and eight reptile species present at the entrances of rabbit warrens. Only four of the taxa recorded on cameras in our study showed a preference for warrens over adjacent above-ground structure, three of them introduced species. The alien commensal species recorded using the burrows were rabbits, house mice (Mus musculus) and feral cats (Felis catus). Conclusions: Rabbit warrens in the IFRNP are an important resource for a range of native and alien commensal species. In our study, they seem to be of special importance for introduced species. Implications: Warren removal in the IFRNP may negatively impact native commensal species in treated areas but is likely to be of long-term net benefit for a wider range of native animals.

Corrigendum to: Unravelling predator–prey interactions in response to planned fire: a case study from the Tanami Desert

Article

Full-text available

Aug 2024

Unravelling predator–prey interactions in response to planned fire: a case study from the Tanami Desert

Article

Full-text available

Jul 2024

Context Introduced predators pose a significant threat to biodiversity. Understanding how predators interact with other threats such as fire is crucial to developing effective conservation strategies. Aims We investigated interactions between the greater bilby (Macrotis lagotis) and two introduced predators, the European red fox (Vulpes vulpes) and feral cat (Felis catus), in response to fire management in a remote part of the Tanami Desert, Australia. Methods We used motion-sensor cameras and non-invasive genetic sampling to monitor bilbies and predators. We compared activity profiles to determine the level of temporal overlap among species, and used generalised linear modelling to assess the correlation between activity and average normalised difference vegetation index (NDVI; as a proxy for fire-associated environmental change). Finally, we used spatially explicit capture–recapture modelling to estimate cat and bilby densities before and after fire. Key results Cat and bilby activity declined following fire, whereas fox activity increased (despite only a small proportion of the study area being burnt). Bilbies and foxes showed the greatest overlap in temporal activity (76%), followed by bilbies and cats (71%) and cats and foxes (68%). Bilbies and cats were more likely to be captured in areas with a lower NDVI, whereas foxes were more likely to be captured in areas with a higher NDVI. Bilby density declined significantly following fire, whereas cat density remained constant through time. Conclusions Declines in bilby activity and density following fire may be attributed to emigration from the study area and/or increases in fox activity. Post-burn emigration could be due to wide scale destruction of important food resources. However, given much of the study area where bilbies were detected remained unburnt, it is more likely that observed declines are related to increases in fox activity and associated increases in predation pressure. Improved understanding may be gained by experimentally manipulating both fire and predator densities. Implications Increases in fox activity following fire are likely to have devastating consequences for the local bilby population. It is thus vital that appropriate management activities are put in place to protect bilbies from foxes. This may be achieved through a combination of lethal control and indirect methods.

Wombat burrows are hotspots for small vertebrates in a landscape subject to gigafire

Article

Full-text available

May 2024

Ecosystem engineers modify their environment and influence the availability of resources for other organisms. Burrowing species, a subset of allogenic engineers, are gaining recognition as ecological facilitators. Burrows created by these species provide habitat for a diverse array of other organisms. Following disturbances, burrows could also serve as ecological refuges, thereby enhancing ecological resistance to disturbance events. We explored the ecological role of Common Wombat (Vombatus ursinus) burrows using camera traps in forests of southeastern Australia. We compared animal activity at paired sites with and without burrows, from the same fire severity class and habitat. We examined how animal activity at Common Wombat burrows was affected by the 2019–20 Black Summer bushfires in Australia. We predicted that burrows would serve as hotspots for animal activity and as refuges in burned areas. The activity of several species including Bush Rat (Rattus fuscipes), Agile Antechinus (Antechinus agilis), Lace Monitor (Varanus varius), Painted Button-quail (Turnix varius), and Grey Shrike-thrush (Colluricincla harmonica) increased at sites where Common Wombat burrows were present, while other species avoided burrows. Species that were more active at burrows tended to be smaller mammal and bird species that are vulnerable to predation, whereas species that avoided burrows tended to be larger mammals that might compete with Common Wombat for resources. Species composition differed between sites with and without burrows, and burrow sites had higher native mammal species richness. The association of several species with burrows persisted or strengthened in areas that burned during the 2019–20 Black Summer bushfires, suggesting that Common Wombat burrows may act as ecological refuges for animals following severe wildfire. Our findings have relevance for understanding how animals survive, persist, and recover following extreme wildfire events.

Observations on the Ecological Role of Burrow-Dwelling Mammals in a Cold, Hyperarid Mountain Habitat

Article

Mar 2024

Historical record shows broad habitat use and rapid decline of the greater bilby Macrotis lagotis in eastern Australia

Article

Apr 2023

Context Understanding historical distributions of species informs their ecology and response to threats, which can support management of surviving and translocated populations. Like many critical weight-range mammals in Australia, the greater bilby (Macrotis lagotis) has experienced major declines since European colonisation. The past distribution of bilbies in eastern Australia remains uncertain owing to the rapidity of their decline, their cryptic and nocturnal nature, and the paucity of specimen records. Aims We aimed to systematically collate, geo-reference and attribute bilby records from eastern Australia to better inform their historical distribution, habitat preferences, patterns of decline and response to threats. Methods We searched explorer and early settler journals, the digitised newspaper archive, interviews with long-term residents, Aboriginal language resources and ethnographies, place and property names, unpublished datasets, and documented locations of now-inactive bilby burrows. Records were geo-referenced and attributed with date, record type, source, location precision, bioregion, habitat and local abundance. The former distribution of bilby habitat in Queensland was modelled using Maxent, and the likely former occupancy of bilbies was identified using vegetation mapping. Key results More than 250 bilby records were found, only 34 of which appear in the Atlas of Living Australia. Sixty-five per cent of the records were attributed either ‘certain’ or ‘good’ reliability. Bilbies formerly occurred over most of inland New South Wales and the southern half of Queensland in areas receiving <600 mm average annual rainfall, in a wide variety of habitats. By the 1930s, bilbies were largely restricted to their current core range in south-western Queensland. This contraction in range coincided with the northward spread of rabbits and foxes. Conclusions Bilbies had a more contiguous distribution and occupied a wider range of habitats than was previously recognised. The species persisted in apparently isolated patches to the south-east, west and north of its present distribution until the 1970s, suggesting recent declines around the peripheries of its current range. By the 1990s, bilbies occupied <3% of their pre-1900 range in eastern Australia. Implications This work details changes in bilby distribution and provides key context for interpreting contemporary survey results. It also identifies areas where further surveys are required and may assist in selecting habitat for future translocations.

Identifying habitat modification by Chinese pangolin in subtropical forests of southern China

Article

Jul 2024
Integr Zool

The excavation of Chinese pangolin ( Manis pentadactyla ) is expected to alter habitat heterogeneity and thus affect the functioning and structure of forest ecosystems. In this study, the bioturbation of Chinese pangolin on forest soils in three regions (Heping, Tianjingshan, and Wuqinzhang) across Guangdong province was quantified. Overall, a mean of 2.66 m ³ ·ha ⁻¹ and 83.1 m ² ·ha ⁻¹ of burrows and bare mounds, respectively, was excavated by Chinese pangolin; the disturbed soils had significantly lower water content and P, C, available N concentrations, but higher bulk density, pH, and microbial abundance than those undisturbed soils. The unevenness of habitat heterogeneity improvement was mainly ascribed to the stronger soil disturbance caused in resting burrows by pangolins. Patterns of altering habitat heterogeneity were site‐specific, with high‐intensity soil disturbance occurring most in shrubs, meadows, steep habitats at high elevations, and mountain tops in Heping, while in broad‐leaved, coniferous and mixed coniferous and broad‐leaved forests away from human settlements in Tianjingshan and upper mountains at high elevations far away from roads and human settlements in Wuqinzhang. Road networks are the main interference for the burrow distribution in Heping and Wuqinzhang and should be programmed.

Housework or vigilance? Bilbies alter their burrowing activity under threat of predation by feral cats

Article

Full-text available

Oct 2023

Behavioral adjustments to predation risk not only impose costs on prey species themselves but can also have cascading impacts on whole ecosystems. The greater bilby (Macrotis lagotis) is an important ecosystem engineer, modifying the physical environment through their digging activity, and supporting a diverse range of sympatric species that use its burrows for refuge and food resources. The bilby has experienced a severe decline over the last 200 years, and the species is now restricted to ~20% of its former distribution. Introduced predators, such as the feral cat (Felis catus), have contributed to this decline. We used camera traps to monitor bilby burrows at four sites in Western Australia, where bilbies were exposed to varying levels of cat predation threat. We investigated the impact of feral cats on bilby behavior at burrows, particularly during highly vulnerable periods when they dig and clear away soil or debris from the burrow entrance as they perform burrow maintenance. There was little evidence that bilbies avoided burrows that were visited by a feral cat; however, bilbies reduced the time spent performing burrow maintenance in the days following a cat visit (P = 0.010). We found the risk posed to bilbies varied over time, with twice the cat activity around full moon compared with dark nights. Given bilby burrows are an important resource in Australian ecosystems, predation by feral cats and the indirect impact of cats on bilby behavior may have substantial ecosystem function implications.

The influence of drought, precipitation and fossorial mammal reintroduction on the density of fossorial arthropods and their burrows in arid Australia

Article

May 2023

The density and abundance of arid‐dwelling taxa often change significantly in response to precipitation fluctuations and the abundance of their predators. The survival and density of burrowing arthropods and their burrows in arid environments following prolonged dry periods and subsequent rains is poorly understood, as is the potential influence of reintroductions of their predators, such as fossorial mammals. The persistence of these arthropods and their burrows may be important for other species that rely on them for food or use their burrows for shelter. In this study, we examined the density of burrowing and ground‐nesting arthropods and their burrows in Australia's Strzelecki Desert over two years between 2019 and 2021. This period spanned the tail‐end of the worst drought on record and subsequent drought‐breaking rains. We employed a Before‐After Control‐Impact (BACI) study design to examine the short‐term effects of a fossorial mammal reintroduction of the greater bilby ( Macrotis lagotis ) into predator‐free fenced exclosures and used an inspection camera to detect the presence of spiders and other taxa within individually marked burrows. We observed the largest changes in arthropod abundance and burrow density between a period that encompassed a third consecutive summer in drought and the commencement of drought‐breaking rains, with some taxa declining by as much as 77% ( p < 0.001). While the density of harvester ant middens erupted over this time, the density of tarantulas, trapdoor spiders and scorpions declined significantly. The greater bilby reintroduction had no short‐term effect on the densities of the arthropods or their burrows, but their arrival may have implications on their post‐drought recovery. Further studies are needed to determine if the significant declines in arthropod populations and burrows are reflective of normal boom‐bust population dynamics due to the poor natural history knowledge of the arthropods we examined.

Bringing Back the Bettong: Reintroducing ecosystem engineers for restoration in Box-Gum grassy woodland

Thesis

Full-text available

Feb 2020

Catherine Ross

The grassy woodlands of eastern Australia have declined in their range by more than 95% through clearing and fragmentation. This decline has coincided with the loss of many digging or soil-foraging species that are considered to be 'ecosystem engineers' because of their role in biopedturbation and effects on other species and processes. Ecosystem engineers are therefore a priority for reintroduction to restore biodiversity and ecosystem function. However, there are gaps in our knowledge of how digging animals affect their environment and potential impacts on recipient ecosystems. The aim of this thesis was to examine the impact of the eastern bettong (Bettongia gaimardi) on ecosystem processes, following their reintroduction to a fenced reserve. It consists of five chapters that explore different aspects of this topic and the implications for management and conservation. Chapter 2 examines biodiversity patterns as a backdrop to bettong reintroduction in a BoxGum grassy woodland. We found that beetle assemblages differed in their composition among distinct ground-layer plant communities at log and tree microhabitats, while beetle communities in open microhabitats were more uniform. Sites with evidence of prior agricultural use also had altered beetle communities. These findings demonstrate the fine-scale structure of the grassy woodland ecosystem as a mosaic of plant and insect communities. Chapter 3 investigates the structural and abiotic effects of bettong and rabbit foraging pits. I found that bettong pits filled in faster than rabbit pits due to their deeper and narrower shape. I did not find any consistent effect on soil nutrients in foraging pits, unlike similar studies in arid areas. Bettong pits reduced daily temperature fluctuations compared to the soil surface. I therefore concluded that in mesic environments, the structural effects of digging may be more important than changes in soil nutrients. Chapter 4 tests the hypothesis that bettong foraging pits provide favourable conditions for seed germination compared to the soil surface. I found that seedling abundance was almost doubled in pits compared to the soil surface. Responses differed between species and years, with native species responding more strongly to the presence of pits than exotic species in the first year. The response was also stronger in denser grassland, suggesting that the driving mechanism for the increased germination is the creation of gaps and reduced competition from the grass canopy. Chapter 5 examines the impact of bettongs on a native geophyte, the early nancy (Wurmbea dioica). I found that bettongs consumed 13-24% of the plants that emerged each year, resulting in a decline in the Wurmbea population over 5 years. However, there was a shift in the population demographics toward younger plants, which may suggest that bettong digging increased recruitment and a possible feedback mechanism. Similar interactions between digging animals and geophytes have been described internationally, but this is the first study in Australia. Finally, Chapter 6 synthesises research on soil-disturbing ecosystem engineers in Australia. I argue that the goals of species reintroductions are often poorly defined, leading to missed opportunities for research and potential negative outcomes. I discuss the factors that should be considered when reintroducing ecosystem engineers and provide a framework for clarifying the goals of species reintroductions. The outcomes of my research suggest that reintroducing extirpated ecosystem engineers may contribute to restoration of grassy woodlands, but they may also have unexpected consequences. Translocations should therefore consider both trophic and engineering effects and be prepared to monitor and manage unexpected outcomes. These findings will inform management of sanctuaries and translocations and contribute to restoration efforts in grassy woodlands in Australia and worldwide.

The Wayward Dog: Is the Australian native dog or Dingo a distinct species?

Article

Full-text available

Sep 2017

The taxonomic identity and status of the Australian Dingo has been unsettled and controversial since its initial description in 1792. Since that time it has been referred to by various names including Canis dingo, Canis lupus dingo, Canis familiaris and Canis familiaris dingo. Of these names C. l. dingo and C. f. dingo have been most often used, but it has recently been proposed that the Australian Dingo should be once again recognized as a full species—Canis dingo. There is an urgent need to address the instability of the names referring to the Dingo because of the consequences for management and policy. Therefore, the objective of this study was to assess the morphological, genetic, ecological and biological data to determine the taxonomic relationships of the Dingo with the aim of confirming the correct scientific name. The recent proposal for Canis dingo as the most appropriate name is not sustainable under zoological nomenclature protocols nor based on the genetic and morphological evidence. Instead we proffer the name C. familiaris for all free-ranging dogs, regardless of breed and location throughout the world, including the Australian Dingo. The suggested nomenclature also provides a framework for managing free-ranging dogs including Dingoes, under Australian legislation and policy. The broad principles of nomenclature we discuss here apply to all free-roaming dogs that coexist with their hybrids, including the New Guinea Singing Dog.

The role of the reintroduction of Greater Bilbies and Burrowing Bettongs in the ecological restoration of an arid ecosystem: foraging diggings, diet and soil seed banks.

Thesis

Full-text available

May 2008

Janet Newell

Arid Recovery, a fenced reserve free of feral predators in arid South Australia, has successfully reintroduced two critical weight range (CWR) mammals, greater bilbies (Macrotis lagotis) and burrowing bettongs (Bettongia lesueur) to facilitate the restoration of arid Australian ecosystems. This thesis evaluates the ecological roles of these reintroduced species and their relationship to ecosystem functioning and the restoration of these ecosystems. Surveys of foraging diggings and soil seed banks, and dietary analysis were used to measure impacts of these species on three main habitats within the Reserve. The results showed that bilbies and bettongs have three major roles in ecosystem functioning: consumers, ecosystem engineers, and dispersers of seeds and fungi. Both bilbies and bettongs were omnivorous, though their diets were distinctly different, with the bilbies focused more on invertebrates and seeds, while the bettongs consumed a greater proportion of coarser plant materials. The seed portion of the diets of both species during 2003-04 differed from a similar study three years previously, shortly after the animals had been reintroduced to Arid Recovery in 2000- 01. During 2003-04, the bilbies consumed a lower proportion of seeds of species of grasses and more of forbs, while seed consumption by bettongs narrowed to be almost exclusively the seeds of shrubs. The number of bilby and bettong diggings varied significantly both spatially and temporally, with averages of 7,530 ± 820 diggings ha-1 in Dunes, 10,560 ± 980 diggings ha-1 in Mulga, and 7,120 ± 610 diggings ha-1 in Swale. This resulted in an average of 2 to 3% disturbance of soil surface area, which is similar to or higher than reported for other Australian or overseas semi-fossorial species. The temporal variation in rates of digging was correlated with minimum daily temperatures and rainfall but not moonlight. This variation was also correlated with counts of bilby but not bettong tracks, suggesting that the temporal variability of diggings was related to levels of bilby activity. The persistence of bilby and bettong diggings differed between the three habitat types, with the majority of the diggings in the Mulga (94%) and Swale (87%) persisting for over 12 months, while Dune diggings filled much faster, with only 15% persisting over 12 months. These diggings were shown to accumulate and bury seeds and litter, and, under some conditions, enhance germination. The seeds of two plant species, the annual grass, Dactyloctenium radulans, and the shrub, Enchylaena tomentosa, germinated from bilby faecal pellets, and over a third of bilby faecal pellets contained fungal spores. Therefore bilbies have the potential to be dispersers of both seeds and fungi. All three major roles of the bilbies and bettongs in ecosystem functioning (consumers, ecosystem engineers, and dispersers of seeds and fungi) have the potential to affect the flows of organic, soil and water resources, and therefore vegetation structure and overall productivity. Soil seed bank densities differed between areas with and without bilbies and bettongs. However, the heterogeneity of the system made it difficult to confidently relate these differences to any particular effects of the bilbies and bettongs. Both bilbies and bettongs were able to locate and dig seeds buried 20 cm deep, and the caches of seed-harvester ants. Experiments showed that in areas of high digging density, 71 to 94% of seed rain accumulated and became buried in diggings. Since bilbies and bettongs have the potential to use buried seed resources, they have the potential to significantly affect soil seed banks through their consumption of seeds, redistribution of seeds through their digging activities and their interactions with other granivorous species. This study is a first step towards understanding the roles of reintroducing CWR mammals to arid ecosystems. Possible longer term effects of these reintroductions will depend on suitable regulation of animal numbers, and climatic patterns, as restorative effects of diggings would be greatest during periods of good rainfall, whereas droughts would slow restorative processes. Although the results of this research are unique for Arid Recovery, the principles of evaluating all major ecological roles of reintroduced species and their interactions with their environment could provide guidance for other reintroductions. These interactions are complex and would require longer-term studies over a range of conditions and locations to further understand the role of reintroducing CWR mammals to ecological restoration.

POSITIVE AND NEGATIVE EFFECTS OF ORGANISMS AS PHYSICAL ECOSYSTEM ENGINEERS

Article

Oct 1997

Action Plan for Australian Mammals 2012

Book

Jan 2014

The Action Plan for Australian Mammals 2012 is the first review to assess the conservation status of all Australian mammals. It complements The Action Plan for Australian Birds 2010 (Garnett et al. 2011, CSIRO Publishing), and although the number of Australian mammal taxa is marginally fewer than for birds, the proportion of endemic, extinct and threatened mammal taxa is far greater. These authoritative reviews represent an important foundation for understanding the current status, fate and future of the nature of Australia. This book considers all species and subspecies of Australian mammals, including those of external territories and territorial seas. For all the mammal taxa (about 300 species and subspecies) considered Extinct, Threatened, Near Threatened or Data Deficient, the size and trend of their population is presented along with information on geographic range and trend, and relevant biological and ecological data. The book also presents the current conservation status of each taxon under Australian legislation, what additional information is needed for managers, and the required management actions. Recovery plans, where they exist, are evaluated. The voluntary participation of more than 200 mammal experts has ensured that the conservation status and information are as accurate as possible, and allowed considerable unpublished data to be included. All accounts include maps based on the latest data from Australian state and territory agencies, from published scientific literature and other sources. The Action Plan concludes that 29 Australian mammal species have become extinct and 63 species are threatened and require urgent conservation action. However, it also shows that, where guided by sound knowledge, management capability and resourcing, and longer-term commitment, there have been some notable conservation success stories, and the conservation status of some species has greatly improved over the past few decades. The Action Plan for Australian Mammals 2012 makes a major contribution to the conservation of a wonderful legacy that is a significant part of Australia’s heritage. For such a legacy to endure, our society must be more aware of and empathetic with our distinctively Australian environment, and particularly its marvellous mammal fauna; relevant information must be readily accessible; environmental policy and law must be based on sound evidence; those with responsibility for environmental management must be aware of what priority actions they should take; the urgency for action (and consequences of inaction) must be clear; and the opportunity for hope and success must be recognised. It is in this spirit that this account is offered. Winner of a 2015 Whitley Awards Certificate of Commendation for Zoological Resource.

Nonparametric estimation of the number of classes in a population

Article

Jan 1984

Anne Chao

Mammalian mesocarnivore visitation at tortoise burrows in a wind farm

Article

Apr 2017
J WILDLIFE MANAGE

There is little information on predator–prey interactions in wind energy landscapes in North America, especially among terrestrial vertebrates. Here, we evaluated how proximity to roads and wind turbines affect mesocarnivore visitation with desert tortoises (Gopherus agassizii) and their burrows in a wind energy landscape. In 2013, we placed motion-sensor cameras facing the entrances of 46 active desert tortoise burrows in a 5.2-km2 wind energy facility near Palm Springs, California, USA. Cameras recorded images of 35 species of reptiles, mammals, and birds. Counts for 4 species of mesocarnivores at desert tortoise burrows increased closer to dirt roads, and decreased closer to wind turbines. Our results suggest that anthropogenic infrastructure associated with wind energy facilities could influence the general behavior of mammalian predators and their prey. Further investigation of proximate mechanisms that underlie road and wind turbine effects (i.e., ground vibrations, sound emission, and traffic volume) and on wind energy facility spatial designs (i.e., road and wind turbine configuration) could prove useful for better understanding wildlife responses to wind energy development. © 2017 The Wildlife Society.

Greater bilby burrows: Important structures for a range of species in an arid environment

Article

Jan 2017

Greater bilbies (Macrotis lagotis) have been described as ecosystem engineers and their burrows are significant structures across an often featureless and harsh arid landscape. Remote cameras were deployed at bilby burrows to determine whether bilby burrows were important structures for other species. Cameras detected two mammal species, brush-tailed mulgara (Dasycercus blythi) and spinifex hopping mice (Notomys alexis), permanently occupying bilby burrows, and a further two species, short-beaked echidnas (Tachyglossus aculeatus acanthion) and sand goannas (Varanus gouldii), regularly using bilby burrows for shelter. An additional suite of 16 mammal, bird, reptile, amphibian and invertebrate species were detected interacting with bilby burrows. There was no difference in the number of species using disused or occupied bilby burrows, indicating that even disused bilby burrows are important structures for other species. We show that bilby burrows are used by a range of species and are analogous to the traditional, mostly North American, and commonly provided text book examples of the gopher tortoise and kangaroo rat. The disappearance of bilbies across at least 80% of their former range and thus the disappearance of their burrows as important structural resources in a harsh, arid environment may have had important consequences for a range of species.

Vertebrate Use of Gopher Tortoise Burrows and Aprons

Article

Dec 2016

Gopher Tortoise (Gopherus polyphemus) burrows are used by more than 60 vertebrate species, but the frequency with which species use burrows and the extent to which other vertebrates use the mound of sand at the burrow entrance, called the burrow apron, has not been quantitatively assessed. Between 2 June and 9 October 2014, we monitored active and inactive adult Gopher Tortoise burrows with motion-triggered trail cameras to identify and enumerate vertebrate burrow visitors. We recorded 12,238 video clips during 2299 trap nights, of which 10,151 (83%) contained a Gopher Tortoise and 1732 (14%) contained other vertebrate species. We reduced multiple videos of a single burrow visitation to 1 observation, resulting in 929 observations of 14 vertebrate species (not including the Gopher Tortoise) using tortoise burrows and 34 species on burrow aprons. Mammals were the most commonly recorded taxa (54%), followed by birds (32%), amphibians (9%), and reptiles (5%). Active burrows were visited more frequently than inactive burrows across all taxa, and burrow aprons were used more frequently than the burrow tunnel. Although active and inactive Gopher Tortoise burrows provide refuge for some vertebrate species, active burrows may provide additional resources, such as increased prey for insectivorous species. More species were found to be present on burrow aprons than within burrows, indicating the apron may be an important microhabitat for species, including those not known to use burrows.

Interspecies co-use of southern hairy-nosed wombat (Lasiorhinus latifrons) burrows

Article

Jan 2016

Burrows can provide refuge for both burrowing and non-burrowing species within harsh environments through protection from climatic extremes, water loss and predation. In Australia, however, despite having a rich diversity of burrowing mammals, little is known about the use of burrows by non-burrowing species. This study aimed to identify the extent of co-use of southern hairy-nosed wombat (Lasiorhinus latifrons) burrows on Wedge Island off the coast of South Australia. Burrow use was monitored using 34 motion-activated cameras placed outside wombat burrows between March and September 2015. Eleven species were found to use burrows, with six commensal species observed using burrows on numerous occasions. These included two mammal species (black-footed rock-wallaby, Petrogale lateralis pearsoni; brush-tailed bettong, Bettongia penicillata), three reptile species (peninsula dragon, Ctenophorus fionni; southern sand-skink, Liopholis multiscutata; White's skink, Liopholis whitii), and one avian species (little penguin, Eudyptula minor). The most common species observed using burrows was the black-footed rock-wallaby, which was recorded using burrows 1795 times. Observations of wombats using burrows were made 1674 times. The prevalent use of burrows on Wedge Island by species other than wombats is an observation with potentially important and broad ecological, conservation, and management implications across Australia's arid and semiarid zones.

Modern Applied Statistics with S

Book

Jan 2002

A guide to using S environments to perform statistical analyses providing both an introduction to the use of S and a course in modern statistical methods. The emphasis is on presenting practical problems and full analyses of real data sets.