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Context. A reliable measure of population size is fundamental to ecology and conservation but is often difficult to obtain. The woylie, Bettongia penicillata, provides an example where ‘getting the numbers right’ has important implications in verifying and quantifying the recent unexpected, rapid and substantial declines across much of its range. Initial estimates prompted a conservation-status upgrade for the species to Endangered by the Australian Government. The present paper constitutes the foundational paper addressing the first steps of a decline diagnosis framework intended to identify the causes of the recent declines.
Aims. To verify whether the declines in woylie trap-capture rates are representative of population change; better quantify the size of the largest woylie populations; and review what is understood about the ecology of the woylie and identify key knowledge gaps that may be relevant to identifying the causes of the recent declines.
Methods. Monitoring data from live-cage trapping (transects and grids), sandpads, woylie diggings and nest-density surveys and spotlighting were collated. Population measures derived from trapping data included capture rates, number of individuals, abundance estimates based on capture–mark–recapture modelling and density using spatially explicit capture–recapture models (SECR).
Key results. The declines in woylie trap-capture rates were verified as real population declines and corresponded closely with other measures of abundance derived from the same trapping data as well as with independent measures. A 95% decline occurred in the largest extant woylie populations (in the Upper Warren region, Western Australia) between 2002 and 2008. At a species level, woylies declined ∼90% (1999–2006), from a peak of ∼200 000 individuals in 1999.
Conclusions. An accurate formal conservation status is an important factor in promoting the conservation of a species. It is recommended that the woylie be considered for Critically Endangered status under the Australian EPBC Act.
Implications. Adequate and effective monitoring of species is critical to detecting and quantifying population changes in a timely manner. Having an accurate measure of population size can have a significant impact on the effectiveness of conservation and management efforts.
Context. Little is known about the importance of bait-site selection during lethal fox-baiting programmes. Improved bait placement may increase the efficacy of baiting and help reduce fox impacts on wildlife and livestock.
Aims. To determine whether bait uptake by the red fox (Vulpes vulpes) differed among five landscape elements (roadsides, fence lines, open paddocks, creek lines and remnant vegetation) and at sites with high or low habitat (ground cover) complexity.
Methods. We measured bait uptake at 300 bait stations distributed evenly among the landscape elements in agricultural landscapes in northern Victoria, Australia. Bait uptake was also compared between sites with low and high habitat complexity in districts subject to no fox control and annual fox control.
Key results. Among landscape elements, bait uptake was significantly higher in roadside vegetation and along vegetated creek lines than it was along fence lines and in open paddocks (P < 0.05 in each case). Within roadside vegetation, bait uptake was significantly (P = 0.001) lower at sites with a high habitat complexity than at sites with low complexity, particularly in areas subject to annual fox control.
Conclusions. Bait placement influences bait-uptake rates considerably and greater consideration should be placed on bait-site selection during fox-baiting programmes. Habitat complexity limited bait uptake, which may indicate a reduced capacity of foxes to find baits in complex habitats.
Implications. Our results should help improve bait-site selection in agricultural landscapes and may increase the efficacy of fox baiting to the benefit of native fauna and livestock.
Context. Many rare and endangered species are threatened by the effects of hybridisation with their domesticated and often numerically dominant relatives. However, factors that influence interactions between hybridising species are poorly understood, thus limiting our ability to develop ameliorative strategies.
Aims. Here, we identify family groups and investigate patterns of gene flow between dingoes (Canis lupus dingo) and domestic dogs (C. l. familiaris) in the Tanami Desert of central Australia. We aimed to determine whether human-provided resources facilitate hybridisation or alter typical patterns of dingo breeding and social behaviour. We also ask whether remote townships are arenas for dingo–dog hybridisation.
Methods. Tissue samples and morphological details were collected from dingo-like animals around two mine sites where humans provide abundant supplementary food and water. Using molecular DNA analyses, we assigned animals to population clusters, determined kinship and the numbers of family groups. Rates of hybridisation were assessed around the mines and in two nearby townships.
Key results. Of 142 samples from mine sites, ‘pure’ dingoes were identified genetically in 89% of cases. This predominance of dingoes was supported by our observations on coat colour and body morphology. Only 2 of 86 domestic dogs sampled at the two townships showed evidence of dingo ancestry. Around the mine sites, there were two distinct population clusters, including a large family group of 55 individuals around a refuse facility.
Conclusions. Where superabundant and consistent food, and reliable water, was available, dingo packs were much larger and co-existed with others, contrary to expectations derived from previous research. Dingo sociality and pack structures can therefore be altered where human-provided food and water are constantly available, and this could facilitate accelerated rates of hybridisation.
Implications. The development of appropriate domestic-waste management strategies should be a high priority in remote areas to ensure only normal rates of population increase by dingoes, and other canids more broadly. It will also potentially impede hybridisation rates if typical canid social and behavioural traits remain intact. Additionally, areas surrounding remote human settlements are likely arenas for accentuated dingo–domestic dog interactions and should be a target for future studies.
Context. Conserving large carnivores can be challenging because of conflicts with human land use and competition with humans for resources. Predation on domestic stock can have negative economic impacts particularly for owners of small herds, and tools for minimising carnivore depredation of livestock are needed. Canids use scent marking to establish territories and avoid intraspecific conflict. Exploiting scent-marking behaviour may provide a means for manipulating canid movements.
Aims. We hypothesised that human-deployed scent marks (i.e. ‘biofence’) could be used to manipulate the movements of grey wolves (Canis lupus) in Idaho, USA.
Methods. We deployed 65 km of biofence within three wolf-pack territories during summer 2010 and 2011 and used location data from satellite-collared wolves and sign surveys to assess the effectiveness of biofencing.
Key results. Location data provided by satellite-collared wolves and sign surveys in 2010 showed little to no trespass of the biofence, even though the excluded areas were used by the packs in previous summers. We also opportunistically deployed a biofence in between a rendezvous site of a resident pack and a nearby sheep grazing allotment; the pack was not implicated in any depredations in summer 2010, even though they had killed sheep every year since 2006. Location data provided by satellite-collared wolves in summer 2011 showed that wolves did trespass biofences.
Conclusions. Biofencing effectively manipulated the movements of wolves in the first year of our study, but not the second.
Implications. Our work suggests that biofencing may be most limited by the apparent necessity to maintain a continuous presence once the biofence is established. The inherent labour and costs associated with such efforts may limit the usefulness of biofencing. Our work can be improved on through further testing that maintains biofencing over a longer timeframe (>3 months), samples several animals per treatment pack, and uses a treatment and control design.
Context. Knowledge of the habitat selection of reintroduced species is crucial to successful re-establishment of viable populations and effective conservation decision-making.
Aims. The aim of our research was to examine habitat selection by reintroduced Eld’s deer (Cervus eldi) in a human-dominated landscape.
Methods. The study was conducted during the period from July 2005 to November 2007 in the Chihao region, a human-dominated area located in western Hainan Island, China. Radio-telemetry was used to monitor 15 collared deer to gain their location information. Resource selection functions were used to quantify habitat selection of the study population at the landscape and home-range scales in both wet and dry seasons.
Key results. At the landscape scale, Eld’s deer showed selection for habitats with scrubland, high elevation, gentle slope, close to water sources and roads. At the home-range scale, Eld’s deer showed selection for habitats with dense forest, scrubland, grassland, low elevation and far away from roads, but they randomly used habitats without special consideration to the distance to water sources. At both landscape and home-range scales, Eld’s deer showed strong avoidance of villages. In addition, Eld’s deer showed increased selection of sparse forests and decreased use of grasslands in the dry season, as compared with the wet season at both spatial scales. Sexual differences in habitat selection existed in reintroduced Eld’s deer. Males showed stronger avoidance to human disturbance, whereas females selected vegetation with higher forage availability but poor hiding cover, especially during the antler-growing period (i.e. wet season).
Conclusions. The habitat selection of reintroduced Eld’s deer was scale-dependent. As a non-fatal anthropogenic factor, human disturbance had a strong influence on habitat selection of Eld’s deer. They more strongly selected slope habitats at relatively high elevations. However, our results also indicated that the reintroduced Eld’s deer had certain adaptive ability and tolerance to the disturbed environment.
Implications. This work provides insight into the habitat selection of reintroduced Eld’s deer in a human-dominated landscape. If the essential food resources are available, the regions at a relatively high elevation with low human disturbance can be considered as potential sites of future Eld’s deer reintroduction.
Context. The release of the highly toxic South American cane toad (Bufo marinus) to the toad-free Australian continent in 1935, and their subsequent rapid spread over large areas of tropical Australia, has resulted in a massive decline of predators such as yellow-spotted goannas (Varanus panoptes) and northern quolls (Dasyurus hallucatus). In spite of dramatic declines of northern quoll populations in the Northern Territory, a few populations still persist in areas of Queensland where northern quolls have co-existed with toads for several decades.
Aims. To determine whether the remaining quoll populations in Queensland have evolved resistance to cane toad toxins.
Methods. The extracellular H1–H2 domain of the α1 subunit of the sodium–potassium-ATPase gene was sequenced in four Queensland as well as four Northern Territory quolls. The transcribed sodium–potassium-ATPase enzyme from this gene is specifically targeted by toad toxins.
Key results. In all of the eight quolls, the sequences representing the 36 bp of the H1–H2 domain of the α1 subunit of the sodium–potassium-ATPase gene were identical.
Conclusions. Our results showed that Queensland quolls have not evolved an increased resistance to the toad toxins. We therefore suggest that the persistence of northern quolls in a few toad infested areas of Queensland could to be due to a combination of optimal habitat quality, and concomitant large quoll numbers, as well as an aversion to feeding on these highly toxic amphibians.
Implications. We suggest that a sample of northern quolls from the Queensland populations should be captured and their response, as well as that of their offspring and grand-offspring, to cane toads should be investigated to guide management of this declining species.
Context. Daily movement responses could indicate food deficiencies threatening population persistence before consequences for population performance become manifested. Animals should respond to food deficiencies by spending less time in foraging areas and hence by moving more frequently between such areas between one day and the next.
Aim. To establish whether the day-to-day movements of a locally threatened ruminant (sable antelope) reflected anticipated seasonal and annual variation in food stress, in comparison with a non-ruminant grazer that was thriving despite being dependent on basically similar food resources (zebra).
Methods. Diel (24 h) displacement distances that were derived from geographic positioning systems (GPS) telemetry were used to make the following comparisons: (1) between benign and adverse seasons, (2) among years differing in rainfall, (3) between the remnant sable herd and herds of zebra in the same region, and (4) between this sable antelope herd and sable herds in a wetter region where food should be more abundant.
Key results. Sable herds generally moved further from day to day in the late dry season than in the wet or early dry season, especially in the years with less rainfall, and greater movement was shown by the sable herd in the drier region than for herds in the wetter region. Zebra herds generally moved further from day to day than the sable herd occupying the same region, but showed less change in their diel displacement distances during the late dry season.
Key conclusions. Findings were consistent with the expected effects of seasonal, annual and regional differences in food availability on the daily movement distances of sable antelope herds.
Implications. Daily movement distances could serve as an indicator of when and where food deficiencies are experienced by sable antelope and perhaps other large ungulates.
Context. Conservation of vulnerable and endangered species requires a comprehensive understanding of their distribution and habitat requirements, so as to implement effective management strategies. Visual scat surveys are a common non-invasive method for monitoring populations. However, morphological similarity of scats among sympatric species presents a problem for accurate identification. Visual misidentifications of scats can have major impacts on the accuracy of abundance and distribution surveys of target species, wasting resources and misdirecting management and conservation actions. DNA identification of scats can overcome this issue, while simultaneously providing a rich source of genetic information for population and dietary studies.
Aims. We developed a simple and reliable method to identify morphologically similar macropod scats from eight sympatric species in north-eastern Australia, using polymerase chain reaction (PCR) and restriction fragment length polymorphism (RFLP) of a portion of the mtDNA ND2 gene.
Methods. We identified a short (275-bp) polymorphic region of ND2, which is easily amplifiable from degraded DNA, developed a primer set, and identified a set of three restriction endonucleases (AluI, BstNI and HphI) which, in combination, can discriminate among the eight target species. So as to test the effectiveness of this protocol, we collected 914 macropod scats from 53 sites in the north-eastern Australia.
Key results. In total, 406 of these scats were extracted, with 398 (98%) containing amplifiable macropod DNA. All 398 scats were subsequently identified to species by using our RFLP protocol. Sequencing of a subset of these samples confirmed the accuracy of the test. Species identification of scats by using DNA identified eight species of macropods, five of which were outside their documented distributions, one of which was ∼400 km.
Conclusions. Our PCR–RFLP method is a simple and efficient means to identify macropod scats to species, eliminating the need for sequencing, which is costly, time-consuming and requires additional laboratory equipment.
Implications. The method allows for rapid and non-invasive assessment of macropod species and is particularly useful for surveying populations across multiple sites.
Context. Woodland caribou (Rangifer tarandus caribou) populations have declined across most of North America. Wolf (Canis lupus) predation on adults is partially responsible for declines; however, caribou declines also can be attributed to low calf survival. Wolves and invading coyotes (C. latrans) may contribute to mortality of calves.
Aim. We assessed wolf and coyote food habits and population and individual level selection for caribou-preferred habitats (bogs and fens) during the caribou calving season (15 April to 30 June) in north-eastern Alberta, Canada, to determine what role these predators might play as a mortality factor for caribou calves.
Methods. We deployed global positioning system and very high-frequency (VHF) radio-collars on 32 wolves and nine coyotes in January 2006 – January 2008, and VHF collars on 42 adult female caribou individuals in 2003–08. We assessed wolf and coyote habitat selection using used-available resource-selection functions, and spatial overlap of wolves and coyotes with caribou using logistic regression to estimate coefficients for latent selection-difference functions. We collected and analysed scats to assess wolf and coyote food habits.
Key results. Wolves generally avoided caribou-preferred habitats, particularly bogs. Most coyotes selected caribou-preferred habitats (bogs and/or fens); however, relative to caribou, they were found closer to upland forests. Hair from adult and calf caribou was uncommon in wolf and coyote diet and caribou is likely to be an uncommon alternative prey for these predators.
Conclusions. We found that >25% of wolf packs and most coyotes selected caribou-preferred habitats during the calving season. Although caribou was not an important prey, limited secondary predation, by these predators and black bears (Ursus americanus), on adult and calf caribou is likely to be contributing to caribou population declines.
Implications. We caution that predation on caribou is likely to escalate as coyotes expand into this region and increasing human disturbance continues to create habitat for white-tailed deer (Odocoileus virginianus), which is an important prey for both wolves and coyotes.
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