No abstract

Habitat fragmentation has been shown to disrupt ecosystem processes such as plant-pollinator mutualisms. Consequently, mating patterns in remnant tree populations are expected to shift towards increased inbreeding and reduced pollen diversity, with fitness consequences for future generations. However, mating patterns and phenotypic assessments of open-pollinated progeny have rarely been combined in a single study. Here, we collected seeds from 37 Eucalyptus incrassata trees from contrasting stand densities following recent clearance in a single South Australian population (intact woodland ¼ 12.6 trees ha À1 ; isolated pasture ¼ 1.7 trees ha À1 ; population area ¼ 10 km 2 ). 649 progeny from these trees were genotyped at eight microsatellite loci. We estimated genetic diversity, spatial genetic structure, indirect contemporary pollen flow and mating patterns for adults older than the clearance events and open-pollinated progeny sired post-clearance. A proxy of early stage progeny viability was assessed in a common garden experiment. Density had no impact on mating patterns, adult and progeny genetic diversity or progeny growth, but was associated with increased mean pollen dispersal. Weak spatial genetic structure among adults suggests high historical gene flow. We observed preliminary evidence for inbreeding depression related to stress caused by fungal infection, but which was not associated with density. Higher observed heterozygosities in adults compared with progeny may relate to weak selection on progeny and lifetime-accumulated mortality of inbred adults. E. incrassata appears to be resistant to the negative mating pattern and fitness changes expected within fragmented landscapes. This pattern is likely explained by strong outcrossing and regular long-distance pollen flow.

ContextAerial surveys provide valuable information about the population status and distribution of many native and pest vertebrate species. They are vital for evidence-based monitoring, budget planning and setting management targets. Despite aircraft running costs, they remain one of the most cost-effective ways to capture distribution and abundance data over a broad area. In Australia, annual surveys of large macropods are undertaken in several states to inform management, and in some jurisdictions, to help set commercial kangaroo harvest quotas. Improvements in the cost efficiencies of these surveys are continually sought. Aerial thermal imaging techniques are increasingly being tested for wildlife surveys, but to date no studies have directly compared population data derived from thermal imaging with data collected by human observers during the same flight. AimsDuring an aerial survey of western grey kangaroos (Macropus fuliginosus), eastern grey kangaroos (M. giganteus) and red kangaroos (Osphranter rufus) across the state of Victoria, Australia, the objective was to conduct a direct comparison of the effectiveness of thermal camera technology and human observers for estimating kangaroo populations from aerial surveys. MethodsA thermal camera was mounted alongside an aerial observer on one side of the aircraft for a total of 1360km of transect lines. All thermal footage was reviewed manually. Population density estimates and distance sampling models were compared with human observer counts. Key resultsOverall, the kangaroo density estimates obtained from the thermal camera data were around 30% higher than estimates derived from aerial observer counts. This difference was greater in wooded habitats. Conversely, human-derived counts were greater in open habitats, possibly due to interference from sunlight and flushing. It was not possible to distinguish between species of macropod in the thermal imagery. ConclusionsThermal survey techniques require refining, but the results of the present study suggest that with careful selection of time of day for surveys, more accurate population estimates may be possible than with conventional aerial surveys. ImplicationsConventional aerial surveys may be underestimating animal populations in some habitats. Further studies that directly compare the performance of aerial observers and thermal imaging are required across a range of species and habitats.

Summary1. Linked demographic-bioclimatic models are emerging tools for forecasting climate change impacts on well-studied species, but these methods have been used in few management applications, and species interactions have not been incorporated. We combined population and bioclimatic envelope models to estimate future risks to the viability of a cockatoo population posed by climate change, increased fire frequency, beak-and-feather disease and reduced management. 2. The South Australian glossy black-cockatoo Calyptorhynchus lathami halmaturinus is restricted to Kangaroo Island, Australia, where it numbers 350 birds and is managed intensively. The cockatoo may be at particular risk from climate change because of its insular geographic constraints and specialised diet on a single plant species, Allocasuarina verticillata. The cockatoo population model was parameterised with mark-resight-derived estimates of survival and fecundity from 13 years of demographic data. Species interactions were incorporated by using a climate-change-driven bioclimatic model of Allocasuarina verticillata as a dynamic driver of habitat suitability. A novel application of Latin Hypercube sampling was used to assess the model's sensitivity to input parameters. 3. Results suggest that unmitigated climate change is likely to be a substantial threat for the cockatoo: all high-CO 2 -concentration scenarios had expected minimum abundances of <160 birds. Extinction was virtually certain if management of nest-predating brush-tail possums Trichosurus vulpecula was stopped, or adult survival reduced by as little as 5%. In contrast, the population is predicted to increase under low-emissions scenarios. 4. Disease outbreak, increased fire frequency and reductions in revegetation and management of competitive little corellas Cacatua sanguinea, were all predicted to exacerbate decline, but these effects were buffered by the cockatoo population's high fecundity. 5. Spatial correlates of extinction risk, such as range area and total habitat suitability, were nonlinearly related to projected population size in the high-CO 2 -concentration scenario. 6. Synthesis and applications. Mechanistic demographic-bioclimatic simulations that incorporate species interactions can provide more detailed viability analyses than traditional bioclimatic models and be used to rank the cost-effectiveness of management interventions. Our results highlight the importance of managing possum predation and maintaining high adult cockatoo survival. In contrast, corella and revegetation management could be experimentally reduced to save resources.