Irruptive population dynamics are characteristic of a wide range of fauna in the world's arid (dryland) regions. Recent evidence indicates that regional persistence of irruptive species, particularly small mammals, during the extensive dry periods of unpredictable length that occur between resource pulses in drylands occurs as a result of the presence of refuge habitats or refuge patches into which populations contract during dry (bust) periods. These small dry-period populations act as a source of animals when recolonisation of the surrounding habitat occurs during and after subsequent resource pulses (booms). The refuges used by irruptive dryland fauna differ in temporal and spatial scale from the refugia to which species contract in response to changing climate. Refuges of dryland fauna operate over timescales of months and years, whereas refugia operate on timescales of millennia over which evolutionary divergence may occur. Protection and management of refuge patches and refuge habitats should be a priority for the conservation of dryland-dwelling fauna. This urgency is driven by recognition that disturbance to refuges can lead to the extinction of local populations and, if disturbance is widespread, entire species. Despite the apparent significance of dryland refuges for conservation management, these sites remain poorly understood ecologically. Here, we synthesise available information on the refuges of dryland-dwelling fauna, using Australian mammals as a case study to provide focus, and document a research agenda for increasing this knowledge base. We develop a typology of refuges that recognises two main types of refuge: fixed and shifting. We outline a suite of models of fixed refuges on the basis of stability in occupancy between and within successive bust phases of population cycles. To illustrate the breadth of refuge types we provide case studies of refuge use in three species of dryland mammal: plains mouse (Pseudomys australis), central rock-rat (Zyzomys pedunculatus), and spinifex hopping-mouse (Notomys alexis). We suggest that future research should focus on understanding the species-specific nature of refuge use and the spatial ecology of refuges with a focus on connectivity and potential metapopulation dynamics. Assessing refuge quality and understanding the threats to high-quality refuge patches and habitat should also be a priority. To facilitate this understanding we develop a three-step methodology for determining species-specific refuge location and habitat attributes. This review is necessarily focussed on dryland mammals in continental Australia where most refuge-based research has been undertaken. The applicability of the refuge concept and the importance of refuges for dryland fauna conservation elsewhere in the world should be investigated. We predict that refuge-using mammals will be widespread particularly among dryland areas with unpredictable rainfall patterns.
Context Buffel grass (Cenchrus ciliaris L.) is an introduced pasture grass that has spread over large areas of semiarid Australia with potentially significant negative consequences for biodiversity. Previous studies suggest that the response of bird communities to the changes in habitat associated with buffel grass invasion is complex. Aims This study compares the behaviour of birds between sub-sites with predominantly native vegetation where buffel grass had been removed and control sub-sites with buffel grass, which were left unmanaged, at two locations in central Australia. Our objective was to evaluate whether removing buffel grass at small scales had measurable benefits for local bird species and to better understand how the presence of buffel grass affects bird behaviour. Methods We assessed differences in microhabitat use and behaviour of all species combined and when separated into above ground, flexible and ground foraging guilds. We also tested for direct correlations between different cover types and the microhabitat use and behaviour of birds within guilds, with some further analyses of three common species individually. Key results Management of buffel grass was associated with changes in the microhabitat use and behaviour of birds when all species were combined and for all foraging guilds. Buffel grass cover was negatively correlated with the proportional time birds spent on the ground and with proportional time spent foraging. However, of the three species examined individually only the behaviour of white-winged trillers (Lalage tricolor) was consistently correlated with ground vegetation cover. Our observations also suggest birds spent less time overall at sites with high buffel grass. Conclusions Managing buffel grass in small areas creates islands of habitat that provide important opportunities for foraging at a localised scale. Buffel grass and other ground cover affects the behaviour of birds collectively, but individual species responses vary. Implications Management of buffel grass in small areas with high conservation value should be considered. Our study will help to inform land managers of the benefits of controlling buffel grass on a localised scale.
Pet cats (Felis catus) often have negative effects on wildlife. This is of growing concern in urban areas as these are increasingly becoming hotspots of native wildlife activity, and as the human population increases, so too does the pet cat population. To maintain biodiversity in urban areas, further knowledge on pet cat behaviour and impacts is required so that management strategies for pet cats are well informed and have public and government support. Here, we offer insights into the wandering activity of pet cats in a patchy urban—heavily vegetated landscape on the east coast of Australia. Our estimated pet cat movement ranges were generally larger than those previously observed in similar landscapes, as well as in more urbanized and rural habitats. Using GPS data loggers, we found that pet cats did not utilize vegetated spaces more than urban areas, nor did they prefer them relative to their availability. Half of our study cats selected urban habitats, whilst the other half displayed no selection or a slight preference for vegetated spaces; these cats had fewer barriers to overcome to reach them. We did not observe any large differences in movements or habitat use between day and night, but displacement distances and preference for vegetated space habitat were marginally lower at night. All pet cats monitored spent most of their time outside their houses. As both urban and vegetated spaces in patchy urban landscapes provide habitat for native wildlife, pet cat activity across both habitat types requires management action.
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