Suchergebnisse

Abstract ContextIn Australia, various species of macropods (family Macropodidae) are known to occur within peri-urban areas, where they can be a source of human–wildlife conflict. Some species, such as the eastern grey kangaroo (Macropus giganteus), have received considerable research attention over the past few years following demands from land managers for evidence-based management guidelines; however, the ecology of other macropod species found in peri-urban areas, such as the eastern wallaroo (Osphranter robustus robustus), remains poorly understood. AimsThe aims were to determine the home range of male and female eastern wallaroos and assess habitat selection in order to define whether wallaroos in a peri-urban environment should be viewed as thriving ('matrix-occupying'), persisting ('matrix-sensitive') or struggling ('urban-sensitive'). MethodsHome range and habitat use of six adult male, five adult female and one subadult male eastern wallaroo were investigated using GPS telemetry between October 2017 and May 2018 in the south-west of Sydney. Key resultsHome ranges (mean±s.e.) of males (63.1±10.2ha) were significantly larger than those of females (31.1±3.3ha). Every adult wallaroo had highly overlapping monthly home ranges, indicating strong site fidelity in all individuals. Eastern wallaroos selected habitats based on vegetation composition during the night and canopy cover during the day. Grassland and open native woodlands were preferred during foraging activities at night. By contrast, human-modified habitats, including hard surfaces and lawns, were avoided at all times by all individuals. ConclusionThe results indicate that eastern wallaroos avoid human-modified features in the landscape, so they could be viewed as persisting ('matrix-sensitive') in peri-urban areas. ImplicationsCompared with matrix-occupying macropods, such as the eastern grey kangaroo, the eastern wallaroo is less likely to cause human–wildlife conflicts – a result of its avoidance of human-modified habitat. Land-use planning, involving green corridors linking remnant vegetation, should be implemented as part of urban planning to enable the persistence of diverse mammal populations in urban areas, particularly matrix-sensitive species.

Context Wildlife is ubiquitous in urban environments, resulting in frequent interactions with humans and human infrastructure. The result of these interactions is often negative, in the form of road injury, orphaning of dependent young or eviction from natural home ranges. Wildlife rehabilitation programmes are devised to counter these negative interactions. However, the success of current management strategies is rarely assessed. Aims We aimed to determine whether short-term survival of juvenile hand-reared common brushtail possums (Trichosurus vulpecula) released in the wild was a function of (1) intrinsic factors such as sex, individual personality and level of human habituation, and (2) extrinsic factors such as release practice (soft vs hard-release) or location (urban vs rural). We also evaluated the relationship between habituation to humans and time spent in care by possums, if presence of conspecifics during the rehabilitation process influenced the development of individual personality, and if this differed in hand-raised animals compared with wild individuals. Methods We radio-tracked and monitored 20 hand-reared juvenile possums (10 females and 10 males) for up to 40 days after release in the wild. Key results Eight possums (40%) survived until the end of the study, nine possums (45%) were killed by foxes or had to be returned into care and three possums (15%) had unknown fates (i.e. lost VHF signal). We found that more exploratory individuals and those less human-habituated were more likely to be successful in the wild in both rural and urban areas, whether or not they were hard or soft released. Conclusions Our results suggest that personality is a key criterion to consider when evaluating the success of rehabilitation programmes. Behavioural traits of hand-reared brushtail possums differed significantly from those of wild individuals, showing that captive conditions can affect the development of personality. Hand-reared possums that spent more time in care were also more likely to display highly human-habituated behaviours. Implications By demonstrating which factors influence success of hand-reared wildlife after release in the wild, our results help in evaluating current rearing and release practices, and improve the evidence base for developing best practice wildlife rehabilitation guidelines.

Habitat destruction and fragmentation, interactions with introduced species or the relocation of animals to form new populations for conservation purposes may result in a multiplication of population bottlenecks. Examples are the translocations of koalas to French Island and its derivative Kangaroo Island population, with both populations established as insurance policies against koala extinction. In terms of population size, these conservation programs were success stories. However, the genetic story could be different. We conducted a genetic investigation of French and Kangaroo Island koalas by using 15 microsatellite markers, 11 of which are described here for the first time. The results confirm very low genetic diversity. French Island koalas have 3.8 alleles per locus and Kangaroo Island koalas 2.4. The present study found a 19% incidence of testicular abnormality in Kangaroo Island animals. Internal relatedness, an individual inbreeding coefficient, was not significantly different in koalas with testicular abnormalities from that in other males, suggesting the condition is not related to recent inbreeding. It could instead result from an unfortunate selection of founder individuals carrying alleles for testicular abnormalities, followed by a subsequent increase in these alleles' frequencies through genetic drift and small population-related inefficiency of selection. Given the low diversity and possible high prevalence of deleterious alleles, the genetic viability of the population remains uncertain, despite its exponential growth so far. This stands as a warning to other introductions for conservation reasons.

Habitat destruction and fragmentation, interactions with introduced species or the relocation of animals to form new populations for conservation purposes may result in a multiplication of population bottlenecks. Examples are the translocations of koalas to French Island and its derivative Kangaroo Island population, with both populations established as insurance policies against koala extinction. In terms of population size, these conservation programs were success stories. However, the genetic story could be different. We conducted a genetic investigation of French and Kangaroo Island koalas by using 15 microsatellite markers, 11 of which are described here for the first time. The results confirm very low genetic diversity. French Island koalas have 3.8 alleles per locus and Kangaroo Island koalas 2.4. The present study found a 19% incidence of testicular abnormality in Kangaroo Island animals. Internal relatedness, an individual inbreeding coefficient, was not significantly different in koalas with testicular abnormalities from that in other males, suggesting the condition is not related to recent inbreeding. It could instead result from an unfortunate selection of founder individuals carrying alleles for testicular abnormalities, followed by a subsequent increase in these alleles' frequencies through genetic drift and small population-related inefficiency of selection. Given the low diversity and possible high prevalence of deleterious alleles, the genetic viability of the population remains uncertain, despite its exponential growth so far. This stands as a warning to other introductions for conservation reasons.