Registered users receive a variety of benefits including the ability to customize email alerts, create favorite journals list, and save searches.
Please note that a BioOne web account does not automatically grant access to full-text content. An institutional or society member subscription is required to view non-Open Access content.
Contact helpdesk@bioone.org with any questions.
Habitat loss as a result of land conversion for agriculture is a leading cause of global biodiversity loss and altered ecosystem processes. Restoration plantings are an increasingly common strategy to address habitat loss in fragmented agricultural landscapes. However, the capacity of restoration plantings to support reproducing populations of native plants and animals is rarely measured or monitored. This review focuses on avifaunal response to revegetation in Australian temperate woodlands, one of the world’s most heavily altered biomes. Woodland birds are a species assemblage of conservation concern, but only limited research to date has gone beyond pattern data and occupancy trends to examine whether they persist and breed in restoration plantings. Moreover, habitat quality and resource availability, including food, nesting sites and adequate protection from predation, remain largely unquantified. Several studies have found that some bird species, including species of conservation concern, will preferentially occupy restoration plantings relative to remnant woodland patches. However, detailed empirical research to verify long-term population growth, colonisation and extinction dynamics is lacking. If restoration plantings are preferentially occupied but fail to provide sufficient quality habitat for woodland birds to form breeding populations, they may act as ecological traps, exacerbating population declines. Monitoring breeding success and site fidelity are under-utilised pathways to understanding which, if any, bird species are being supported by restoration plantings in the long term. There has been limited research on these topics internationally, and almost none in Australian temperate woodland systems. Key knowledge gaps centre on provision of food resources, formation of optimal foraging patterns, nest-predation levels and the prevalence of primary predators, the role of brood parasitism, and the effects of patch size and isolation on resource availability and population dynamics in a restoration context. To ensure that restoration plantings benefit woodland birds and are cost-effective as conservation strategies, the knowledge gaps identified by this review should be investigated as priorities in future research.
Context. By the early 1900s, river otters (Lontra canadensis) were extirpated across large parts of their range in North America. Over the last several decades they have made a remarkable recovery through widespread reintroduction programs. River otters were reintroduced in Ohio, USA, between 1988 and 1993, and restricted and limited harvesting of this population began in 2005. While circumstantial evidence points to rapid population growth following the reintroduction, changes in population size over time is unknown.
Aims. We sought to model river otter population growth following reintroduction, and to assess the impact of harvesting.
Methods. We used empirical and literature-based data on river otter demographics in Ohio to estimate abundance from 1988–2008 using an age- and sex-specific stochastic Leslie matrix model. Additionally, we used statistical population reconstruction (SPR) methods to estimate population abundance of river otters in Ohio from 2006 to 2008.
Results. Our Leslie matrix model predicted a population size of 4115 (s.d. = 1169) in 2005, with a population growth rate (λ) of 1.28 in 2005. Using SPR methods we found that both trapper effort and initial population abundance influenced our population estimates from 2006 to 2008. If we assumed that river otter pelt price was an accurate index of trapper effort, and if the initial population was between 2000 and 4000, then we estimated the λ to be 1.27–1.31 in 2008 and the exponential rate to be 0.17–0.21 from 2006 to 2008. Conversely, if the river otter population in 2005 was 1000, then we estimated λ to be 1.20 in 2008 and the exponential rate to be 0.08 from 2006 to 2008.
Conclusions. The river otter population in Ohio appears to have had the potential to grow rapidly following reintroduction. The ultimate effect of the harvesting regime on population abundance, however, remains clouded by limited data availability and high variability.
Implications. The considerable uncertainty surrounding population estimates of river otters in Ohio under the harvesting regime was largely driven by lack of additional data. This uncertainty clouds our understanding of the status of river otters in Ohio, but a more robust, long-term monitoring effort would provide the data necessary to more precisely monitor the population.
Context. Dogs are often used to find rare or cryptic species, but search methods are not standardised, making it difficult to interpret and compare results. Standardised approaches are needed to optimise search effectiveness and/or efficiency. Designing an optimal search strategy requires knowledge of the effective sweep width, which is related to the probability of detection (POD) at various distances between the searcher and the search object.
Aims. Our primary aim was to estimate effective sweep width for wildlife-detector dogs searching for rodents. We also tested whether dogs differed in their reaction on encountering a laboratory rat (Rattus norvegicus) or a wild-caught Norway rat (wild-type R. norvegicus).
Methods. We conducted field trials using trained rodent-detector dogs to locate dead laboratory rats. We used the numbers of detections and non-detections at distances of 0–100 m to estimate detection probability and effective sweep width.
Key results. Dog teams located 100% of rats (regardless of strain) placed directly in their search path. POD declined rapidly with an increasing distance, yielding an observed detection rate of 33% at 10 m, and close to zero at ≥20 m. The data were best described by an exponential decay function. Effective sweep width was estimated to be 16.8 m (95% confidence interval 12.3–21.4 m), corresponding to a strip extending 8.4 m on either side of a walked track. Handlers could not consistently judge whether a dog had encountered a laboratory rat or a wild rat.
Conclusions. Our results suggest that when dogs are >10 m from a source of rat odour, POD declines sharply. We estimate that the effective distance explored when searching for a stationary rodent is 8.4 m either side of the search path.
Implications. This information will allow users to optimise the search pattern that dog teams should follow for a given search scenario.
Context. Camera trapping is commonly employed for studying carnivores because it provides better data than do other methods, and with lower costs. Increasing the probability of detecting the target species can reduce parameter uncertainty and survey effort required to estimate density and occurrence. Different methods, including attractants and baits, can be used to increase detectability. However, their efficacy has rarely been quantitatively assessed.
Aims. To quantify the efficacy of scent and bait attractants to increase the detection probability of mesocarnivores by camera trapping.
Methods. We tested two scent lures, valerian extract (Val) and lynx urine (LU), their combination (Val–LU), and a non-reward bait (i.e. not accessible to the animal), raw chicken, as carnivore attractants in two protected areas of central Spain. We used camera-trapping records under an occupancy-modelling framework to estimate attractant-specific detection probabilities for six mesocarnivore species, and quantified their effects by comparing these estimates with the baseline (i.e. no attractant) detectability.
Key results. The weekly detection probability of four mesocarnivore species (red fox, Vulpes vulpes, stone marten, Martes foina, common genet, Genetta genetta, and Eurasian badger, Meles meles) significantly increased when Val–LU (between 0.11 ± 0.07 and 0.67 ± 0.05) or chicken (between 0.31 ± 0.02 and 0.77 ± 0.22) were used as attractant, when compared with baseline detectability (between 0.01 ± 0.02 and 0.29 ± 0.05). Although rarely, wildcats (Felis silvestris) were mostly detected with Val–LU. The probability of detecting a species after k sampling occasions (7 days each) where it was present was highly improved with both Val–LU and chicken for all species (e.g. from 0.20 to 0.98 after four sampling occasions with chicken for the stone marten). Both attractants reduced the sampling time required to ascertain that a species was absent to between 42% and 15% of baseline values.
Conclusions. The tested attractants greatly improved the detectability of most Iberian mesocarnivores. Although chicken was preferable for some species such as stone marten, Val–LU is most efficient for detecting the whole mesocarnivore community, including rare species such as wildcats.
Implications. Attractant selection in studies using non-invasive detection methods must be supported by quantitative assessment of the detection probability associated to each attractant. Researchers must choose those attractants best fitting target species and study aims.
Context. Feral cats are a significant threat to native wildlife and broad-scale control is required to reduce their impacts. Two toxic baits developed for feral cats, Curiosity® and Hisstory®, have been designed to reduce the risk of baiting to certain non-target species. These baits involve encapsulating the toxin within a hard-shelled delivery vehicle (HSDV) and placing it within a meat attractant. Native animals that chew their food more thoroughly are predicted to avoid poisoning by eating around the HSDV. This prediction has not been tested on wild native mammals in the monsoonal wet–dry tropics of the Northern Territory.
Aim. The aim of this research was to determine whether northern quolls (Dasyurus hallucatus) and northern brown bandicoots (Isoodon macrourus) would take feral cat baits and ingest the HSDV under natural conditions on Groote Eylandt.
Methods. We hand-deployed 120 non-toxic baits with a HSDV that contained a biomarker, Rhodamine B, which stains animal whiskers when ingested. The species responsible for bait removal was determined with camera traps, and HSDV ingestion was measured by evaluating Rhodamine B in whiskers removed from animals trapped after baiting.
Key results. During field trials, 95% of baits were removed within 5 days. Using camera-trap images, we identified the species responsible for taking baits on 65 occasions. All 65 confirmed takes were by native species, with northern quolls taking 42 baits and northern brown bandicoots taking 17. No quolls and only one bandicoot ingested the HSDV.
Conclusion. The use of the HSDV reduces the potential for quolls and bandicoots to ingest a toxin when they consume feral cat baits. However, high bait uptake by non-target species may reduce the efficacy of cat baiting in some areas.
Implications. The present study highlighted that in the monsoonal wet–dry tropics, encapsulated baits are likely to minimise poisoning risk to certain native species that would otherwise eat meat baits. However, further research may be required to evaluate risks to other non-target species. Given the threat to biodiversity from feral cats, we see it as critical to continue testing Hisstory® and Curiosity® in live-baiting trials in northern Australia.
Context. Livestock predation is a worldwide phenomenon, causing financial losses and emotional strain on producers. Wild dogs (Canis familiaris) cause millions of dollars of damage to cattle, sheep and goat production in Australia every year, and despite on-going control (baiting, trapping, shooting, and fencing), they remain a significant problem for livestock producers across many pastoral and agricultural regions of Australia.
Aims. We aimed to quantify the uptake of dried meat baits by wild dogs and determine whether an olfactory lure (fish oil) could increase uptake.
Methods. Camera traps and sand pads were used to monitor bait uptake for three baiting events on two pastoral properties in the southern rangelands of Western Australia in 2016 and 2017.
Key results. Of the 337 monitored baits with a known outcome, young wild dogs (<8 months old) removed only four, three of which were covered in a fish-oil lure. In warmer months, baits were largely consumed by varanids, and in cooler months, when baits were taken it was predominantly by corvids. Varanids and corvids took more baits than expected on the basis of activity indices. Kangaroos, feral cats and wild dogs consumed significantly fewer baits than expected from their activity on camera.
Conclusions. We have no evidence that adult wild dogs removed baits, despite many opportunities to do so (wild dogs passing cameras), and fewer wild dogs took baits than expected on the basis of activity events seen on camera. Olfactory lures may have the potential to increase bait uptake by naïve individuals (i.e. young dogs), but the sample size was small.
Implications. Increasing the number of baiting events per year, trialling novel baits, and baiting during low non-target activity are some of the recommended methods that may increase bait persistence and uptake by wild dogs.
Context. Climate change is causing changes to seasonal food resources, with critical health and survival impacts for many species. The endangered Burramys parvus (mountain pygmy-possum) predominantly consumes Agrotis infusa (Bogong moth), a long-distance seasonal migrant.
Aims. We aimed to examine direct and indirect climate-related influences on B. parvus food resources so as to assess the susceptibility of the species to climate change.
Methods. We analysed a long-term (17-year) data record of B. parvus faecal samples from sites across a climate gradient, in relation to plant-growth indices derived from climate data. We also modelled the population dynamics of A. infusa against climate variables and in relation to the probability of consumption by B. parvus.
Key Results. The diet of B. parvus was highly variable among sites and years and there were strong seasonal patterns for predominant food resources (A. infusa, other local arthropods, Podocarpus sp. and other local seeds). Seasonal patterns generally diminished with an increasing elevation, which may be due to resource availability or complex interactions with food preferences. Growth conditions across spatially far removed A. infusa breeding grounds influenced their abundance recorded in the Alps in spring, which was reflected in B. parvus diet.
Conclusions. Strong seasonal and climatic influences on dominant food resources suggest that B. parvus may be susceptible to climate change. Selective foraging for the lipid-rich A. infusa and Podocarpus sp. seed suggests that there may be important health and survival benefits for B. parvus.
Implications. Given the dependence on cooler, higher-elevation aestivation sites, A. infusa may have reduced survival in a warmer world. Climate change across the vast migratory route of A. infusa is likely to further affect survival and availability for consumption by B. parvus. Predicted increases in fire frequency and severity may reduce availability of the fire-sensitive Podocarpus sp. The health and survival of B. parvus may be compromised as a result of reduced availability of A. infusa and Podocarpus seed and a greater dependence on angiosperm plants (seeds and nectar) and local arthropods because of the consequent change in dietary lipid composition. Integrated predictive modelling of A. infusa and B. parvus population dynamics under future climate-change scenarios is recommended.
Context. Population estimation and monitoring are important tools for the support of programs and actions of conservation for most wildlife species, including birds. For validation of such support, a set of reliable, consistent and comparable parameter estimates is essential (through systematic monitoring over time), in addition to studies on ecological aspects of the species.
Aims. In this study, our aim was to analyse the population of Penelope superciliaris in the Vale Natural Reserve (VNR), located in north-eastern Espírito Santo, Brazil, providing estimates of density, population size and activity. We also analysed occupancy and detectability of the species, relating them to six covariates (distance from forest edge, water and road, as well as poaching intensity, canopy cover and understorey cover) based on previous knowledge of the ecology of rusty-margined guan.
Methods. We used line-transect surveys to estimate density and abundance, and camera traps to estimate habitat use by P. superciliaris, using the occupancy modelling approach.
Key results. Estimated density for P. superciliaris was 2.5 ± 1.0 groups per km2 with a group size of 6.0 ± 2.0 individuals, and estimated population size for the entire VNR was 3544 ± 495 individuals. Occupancy by P. superciliaris was best described by three covariates: (1) distance to road; (2) distance to water; and (3) poaching intensity. Detectability was affected by two covariates: (1) understorey cover; and (2) poaching intensity.
Conclusions. Our results provide the first information on density, habitat use and activity of P. superciliaris in the VNR. We concluded that P. superciliaris is active diurnally, especially during morning and late afternoon, prefers areas near water sources in denser forests and tends to avoid areas with habitat modification and intense poaching activity.
Implications. Our data highlight the impact of poaching on the species and can be useful as a baseline for future studies and Cracid conservation plans.
Context. Vehicle strike is a major issue where wildlife habitat is intersected by busy roads. Near Threatened Lumholtz’s tree-kangaroo (Dendrolagus lumholtzi) is a large (5–10 kg) semi-arboreal mammal found in populated rural and forested areas of north-eastern Australia. Warning signs, rope bridges and underpasses have not prevented ∼20 animals being killed on the road each year.
Aims. To identify factors influencing Lumholtz’s tree-kangaroo vehicle strike to help inform mitigation options.
Methods. Citizen sightings (1998–2000) and 90 road-kills collected over 4.5 years on the Atherton Tablelands, Australia, were examined to determine the causes of vehicle strike in Lumholtz’s tree-kangaroo. The spatial distributions of sightings and road-kills were characterised using nearest-neighbour analysis, and the relationship between them was determined using a Bayesian approach that accounted for spatial autocorrelation. Gender, age, weight, season, rainfall, road and verge characteristics, traffic volumes, speed limits and mitigation measures were recorded to assess their influence on road-kill risk. Adequacy of speed limits to prevent collisions along road sections with more than four road-kills per 8 km (hazard zones) was assessed from visibility and stopping distances.
Key results. Vehicle strikes mainly affected male tree-kangaroos (2–5 years, 5.5–8 kg), occurred where live animals were most frequently sighted and were most likely on roads with narrow verges, low visibility and medium traffic volumes. Speed limits at hazard zones were inadequate to prevent collisions. Few warning signs corresponded with these zones, and road mortalities persisted where they did.
Conclusions. Unpredictable dispersal of young males and vehicle speeds unsuited to road conditions drive road mortalities in Lumholtz’s tree-kangaroo. Because tree-kangaroos do not appear to respond to existing mitigation measures, reducing traffic speeds, and increasing visibility, appear to be the most effective mitigation strategies for reducing tree-kangaroo road mortality.
Implications. Our findings suggest that tree-kangaroo road-kill can be reduced by reducing speed limits in line with government recommendations and increasing visibility by clearing road verges along sections of road with the highest tree-kangaroo mortality. Warning signage should be re-evaluated to determine whether its effectiveness can be improved.
This article is only available to subscribers. It is not available for individual sale.
Access to the requested content is limited to institutions that have
purchased or subscribe to this BioOne eBook Collection. You are receiving
this notice because your organization may not have this eBook access.*
*Shibboleth/Open Athens users-please
sign in
to access your institution's subscriptions.
Additional information about institution subscriptions can be foundhere