Failure to Respond to Food Resource Decline Has Catastrophic Consequences for Koalas in a High-Density Population in Southern Australia

Understanding the ability of koalas to respond to changes in their environment is critical for conservation of the species and their habitat. We monitored the behavioural response of koalas to declining food resources in manna gum (Eucalyptus viminalis) woodland at Cape Otway, Victoria, Australia, from September 2011 to November 2013. Over this period, koala population density increased from 10.1 to 18.4 koalas.ha^-1. As a result of the high browsing pressure of this population, manna gum canopy condition declined with 71.4% manna gum being completely or highly defoliated in September 2013. Despite declining food resources, radio collared koalas (N = 30) exhibited high fidelity to small ranges (0.4–1.2 ha). When trees became severely defoliated in September 2013, koalas moved relatively short distances from their former ranges (mean predicted change in range centroid = 144 m) and remained in areas of 0.9 to 1.0 ha. This was despite the high connectivity of most manna gum woodland, and close proximity of the study site (< 3 km) to the contiguous mixed forest of the Great Otway National Park. Limited movement had catastrophic consequences for koalas with 71% (15/21) of radio collared koalas dying from starvation or being euthanased due to their poor condition between September and November 2013.     

Difficulties of assessing the impacts of the 2019–2020 bushfires on koalas

The 2019–2020 Australian bushfires were unprecedented both in extent and severity, impacting wildlife through direct mortality as well as habitat damage. More than 10% of koala habitat is estimated to have been affected by fires. Estimating the number of koalas lost is crucial to assess koala conservation status and to determine the appropriate management actions required. However, this is not a trivial task, as accurate data on koala distribution and population density before the fires is patchy. Acknowledging this weakness, we sought to estimate fire impact on koalas at specific sites, by comparing habitat areas affected by the fire with habitat areas that were unaffected by the fire, pairing closely related study sites (based on geography and vegetation). To compare koala density, we deployed two koala detection methods; drone-acquired thermal imagery and detection dogs coupled with genetic fingerprinting, in four fire-affected sites paired with four control sites in New South Wales and Queensland. Through drone surveys, we detected 140 koalas in 5,240 ha in New South Wales. The detection dogs found 144 scat samples corresponding to 79 unique koalas in 77 ha of transects in Queensland. Our preliminary results show many koalas were still present in fire-affected areas after the 2019–2020 bushfire season. Koala density was 24 to 71% lower in fire-affected sites compared with control sites in three of the habitat pairs, whereas unexpectedly, in the fourth pair, we observed a 317% higher koala density in the fire-affected site. This underlined that koalas can be present in fire-affected areas and that monitoring their health could be critical for months after the fires.     

Estimating koala density from incidental koala sightings in South‐East Queensland,Australia (1997–2013), using a self‐exciting spatio‐temporal point process model

The koala, Phascolarctos cinereus, is an iconic Australian wildlife species facing a rapid decline in South‐East Queensland (SEQLD). For conservation planning, the ability to estimate the size of koala populations is crucial. Systematic surveys are the most common approach to estimate koala populations but because of their cost they are often restricted to small geographic areas and are conducted infrequently. Public interest and participation in the collection of koala sighting data is increasing in popularity, but such data are generally not used for population estimation. We modeled monthly sightings of koalas reported by members of the public from 1997 to 2013 in SEQLD by developing a self‐exciting spatio‐temporal point process model. This allowed us to account for characteristics that are associated with koala presence (which vary over both space and time) while accounting for detection bias in the koala sighting process and addressing spatial clustering of observations. The density of koalas varied spatially due to the heterogeneous nature of koala habitat in SEQLD, with a mean density of 0.0019 koalas per km² over the study period. The percentage of land areas with very low densities (0–0.0005 koalas per km²) remained similar throughout the study period representing, on average, 66% of the total study area. The approach described in this paper provides a useful starting point to allow greater use to be made of incidental koala sighting data. We propose that the model presented here could be used to combine systematic koala survey data (which is spatially restricted, but more precise) with koala sighting data (which is incidental and often biased by nature, but often collected over large geographical areas). Our approach could also be adopted for modeling the density of other wildlife species where data is collected in the same manner.     

Translocation of overabundant species: Implications for translocated individuals

Effective management of overabundant animal populations is a difficult challenge for wildlife managers around the globe. Translocation is often considered a viable management tool, whereby individual animals are removed from areas of high population density and released in areas where densities are lower. Typically, the success of a translocation program is measured at the population source, with little attention given to the fate of translocated individuals. Here we use a koala (Phascolarctos cinereus) translocation program from southeastern Australia as a case study to investigate the effects of translocation on individual animals. The koala is an iconic species that occurs at high densities in some parts of its southern range, leading to numerous conservation and animal welfare issues. Between 1997 and 2007 over 3,000 koalas from a high-density island population were captured, surgically sterilized, and translocated to the mainland. Annual post-translocation surveys at release sites revealed densities of ≤0.4 koalas/ha, despite release densities of 1.0 koala/ha. Radiotracking studies indicate that low densities were because of both mortality and high dispersal of translocated individuals. We observed a mortality rate of 37.5% for translocated koalas in the first 12 months post-release. No deaths occurred among animals that were not sterilized and translocated. Translocated koalas moved greater distances than non-translocated animals. Monitoring of translocated individuals should be performed routinely during translocation programs for overabundant species. Due consideration must be given to what is an acceptable level of mortality for translocated individuals. Although often considered an ethically acceptable management technique (especially for iconic and charismatic species), translocation may not always be the best option from an animal welfare perspective. © 2012 The Wildlife Society.     

Genetic structure and diversity of the koala population in South Gippsland,Victoria: a remnant population of high conservation significance

In the Australian state of Victoria, the history of koalas and their management has resulted in the homogenisation and reduction of genetic diversity in many contemporary populations. Decreased genetic diversity may reduce a species’ ability to adapt to future environmental pressures such as climate change or disease. The South Gippsland koala population is considered to be unique in Victoria, as it is believed to be a remnant population, not originating from managed populations that have low genetic variation. This study investigated genetic structure and diversity of koalas in South Gippsland, with comparison to other populations in Victoria (French Island/Cape Otway, FI and Raymond Island, RI), New South Wales and south east Queensland. Population analyses were undertaken using both microsatellite genotype and mitochondrial DNA sequence data. Non-invasive sampling of koala scats was used to source koala DNA, allowing 222 South Gippsland koalas to be genotyped. Using nuclear data the South Gippsland koala population was found to be significantly differentiated (D_jost 95% CI SG–RI?=?0.03–0.06 and SG–FI?=?0.08–012) and more diverse (A_R 95% CI SG?=?4.7–5.6, RI?=?3.1–3.3, FI?=?3.0–3.3; p?=?0.001) than other Victorian koala populations, supporting the premise that koalas in the South Gippsland region are part of a remnant population, not derived from translocated island stock. These results were also supported by mitochondrial data where eight haplotypes (Pc4, Pc17, Pc26, Pc27, and Pc56–Pc59) were identified in South Gippsland while a single haplotype (Pc27) was found in all island koalas tested. Compared to other Victorian koala populations, greater genetic diversity found in South Gippsland koalas, may provide this population with a greater chance of survival in the face of future environmental pressures. The South Gippsland koala population is, therefore, of high conservation significance, warranting the implementation of strategies to conserve this population and its diversity into the future.     

Distribution,abundance, and habitat use of introduced <Emphasis Type="Italic">Boa constrictor</Emphasis> threatening the native biota of Cozumel Island,Mexico

Species introductions are among the most pervasive types of disturbance, seriously affecting island biota and ecosystem dynamics. The management of introduced generalist species, which may live in a wide range of environmental conditions, can be particularly difficult and is a major challenge for the conservation of native insular species. Boa constrictor was introduced onto Cozumel Island, Mexico, in 1971. The introduction of this generalist predator has affected negatively the native species (many of them endemic to the island) on which the boa feed. It is important to determine temporal variation in boa abundance, the areas of the island in which boas live, and the vegetation types they use in order to develop management strategies to reduce boa pressure on the native biota. We used nocturnal road transect sampling and occasional boa encounters during field work, to estimate boa distribution, abundance and habitat use, taking into account its spatiotemporal patterns on Cozumel Island. This study confirms that Boa constrictor is well established, widespread, and abundant on the island. Our results show that boas are distributed throughout Cozumel, in all vegetation types and geographical regions. Overall, there were 0.11 ± 0.03 boa/10 km road transect. There were no significant spatiotemporal differences in boa activity (time of day) and abundance (monthly, seasonally, by vegetation types or regions of the island). According to the habitat use analysis, there were, however, fewer boas than expected in the subdeciduous tropical forest we sampled and in the central-northern region of the island, which coincide with areas inhabited by humans. There were more boas in areas uninhabited by humans, and there was a tendency towards a greater proportion of dead boas in inhabited areas and live boas in uninhabited areas. Cozumel boas are habitat generalists, which are affected by human induced mortality in inhabited areas. There is a vast area uninhabited by humans, with natural vegetation, on the island where boas have suitable habitats available for their continuous existence on Cozumel. This situation, and the adaptability of the boa, makes the control or eradication of this introduced species a critical conservation challenge.     

Ranging Behavior of an Arboreal Marsupial in a Plantation Landscape

Forests are becoming increasingly fragmented, primarily because of their conversion to production landscapes. Animals occupying modified landscapes may need to expand their ranges and move longer distances between remnant forest patches to find resources. The establishment of plantations in fragmented landscapes, however, may provide complementary habitat for wildlife and improve connectivity, reducing the amount of movement required. Our objective was to determine the influence of plantations on koala (Phascolarctos cinereus) habitat use and test 2 competing hypotheses on the relationship between plantations and range size. We deployed global positioning system and very high frequency collars on 40 koalas in 2 landscapes (plantation and non-plantation) in Victoria, Australia. From 68,216 tracking points collected over an 8-month period, we calculated and compared seasonal home range size and habitat use between landscapes. There was no difference in range size, the size and number of core use areas, or the distance between core use areas between plantation and non-plantation landscapes. Plantations extend existing koala habitat and facilitate koala movement through a landscape; however, remnant native vegetation is still more frequently used. Consequently, native vegetation (even fragmented, linear roadside vegetation) is of high conservation importance for the persistence of koalas in modified landscapes. © 2020 The Wildlife Society.     

Habitat management by aboriginals promotes high spider diversity on an Asian tropical island

Orchid Island, 92  km off the southeast coast of Taiwan, has the northernmost tropical forests in East Asia. We assessed effects of habitat management by Orchid Island inhabitants, the Yami people, on spider diversity by comparing assemblages collected from the ground to canopy among four habitats (natural forest, cultivated woodland, second growth forest and grasslands) that receive different degrees of disturbance. Species and guild composition did not differ among replicates of habitat but differed significantly among habitats. Variation in spider diversity was inversely correlated with vegetation density. Cultivated woodland subjected to an intermediate level of disturbances had a lower understory vegetation density than natural forest, but higher spider diversity. Neither insect abundance nor biomass varied significantly among habitats suggesting little room for effects of prey availability on spider diversity. It appears that the Yami people maintain high spider diversity on Orchid Island by generating novel habitat types with different vegetation structures and disturbance regimes.     

The Abundance and Distribution of Wolverines in British Columbia,Canada

ABSTRACT The abundance and distribution of carnivores and their habitat are key information needed for status assessment, conservation planning, population management, and assessment of the effects of human development on their habitat and populations. We developed a habitat quality rating system, using existing wolverine (Gulo gulo) distribution, wolverine food, ecosystem mapping, and human development data. We used this and empirically derived estimates of wolverine density to predict wolverine distribution and abundance at a provincial scale. Density estimates for wolverines in high-quality habitat averaged 6.2 wolverines/1,000 km² (95% CI = 4.2–9.5). We predicted mean densities ranging from 0.3/1,000 km² in rare-quality habitat to 4.1/1,000 km² in moderate-quality habitat. Our predicted population estimate for wolverines in British Columbia was 3,530 (95% CI = 2,700-4,760). We predicted highest densities of wolverines in interior mountainous regions, moderate densities in interior plateau and boreal forest regions, and low densities in mainland coastal regions and drier interior plateaus. We predicted that wolverines would be rare on Vancouver Island, along the outer mainland coast, and in the dry interior forests, and absent from the Queen Charlotte Islands, interior grassland environments, and areas of intensive urban development.     

Influences on koala habitat selection across four local government areas on the far north coast of NSW

Conserving habitats crucial for threatened koala (Phascolarctos cinereus) populations requires rating habitat quality from a fine spatial scale to patches, landscapes and then regions. The koala has a specialized diet focused on the leaves of a suite of Eucalyptus species. We asked: what are the key regional influences on habitat selection by koalas in the far north coast of New South Wales? We addressed this question by investigating the multi-scale factors, and within-scale and cross-scale interactions, that influence koala habitat selection and distribution across four local government areas on the far north coast of New South Wales. We assembled and analysed a large data set of tree selection, identified by the presence of scats, in a wide range of randomly selected 5 × 5 km grids across the region. This resulted in more than 9000 trees surveyed for evidence of koala use from 302 field sites, together with associated biophysical site features. The dominant factor influencing habitat use and koala occurrence was the distribution of five Eucalyptus species. Koalas were more likely to use medium-sized trees of these species where they occurred on soils with high levels of Colwell phosphorous. We also identified new interactions among the distribution of preferred tree species and soil phosphorous, and their distribution with the amount of suitable habitat in the surrounding landscape. Our study confirmed that non-preferred species of eucalypts and non-eucalypts are extensively used by koalas and form important components of koala habitat. This finding lends support to restoring a mosaic of koala-preferred tree species and other species recognized for their value as shelter. Our study has provided the ecological foundation for developing a novel regional-scale approach to the conservation of koalas, with adaptability to other wildlife species.     

Abundance and habitat relationships of breeding birds in the Sky Islands and adjacent Sierra Madre Occidental of northwest Mexico

The Sierra Madre Occidental and neighboring Madrean Sky Islands span a large and biologically diverse region of northwest Mexico and portions of the southwestern United States. Little is known about the abundance and habitat use of breeding birds in this region of Mexico, but such information is important for guiding conservation and management. We assessed densities and habitat relationships of breeding birds across Sky Island mountain ranges in Mexico and adjacent portions of the Sierra Madre from 2009 to 2012. We estimated densities at multiple spatial scales, assessed variation in densities among all major montane vegetation communities, and identified and estimated the effects of important habitat attributes on local densities. Regional density estimates of 65% of 72 focal species varied significantly among eight montane vegetation communities that ranged from oak savannah and woodland at low elevations to pine and mixed‐conifer forest at high elevations. Greater proportions of species occurred at peak densities or were relatively restricted to mixed‐conifer forest and montane riparian vegetation likely because of higher levels of structural or floristic diversity in those communities, but those species were typically rare or uncommon in the Sky Islands. Fewer species had peak densities in oak and pine‐oak woodland, and species associated with those communities were often more abundant across the region. Habitat models often included the effects of broadleaf deciduous vegetation cover (30% of species), which, together with tree density and fire severity, had positive effects on densities and suggest ways for managers to augment and conserve populations. Such patterns combined with greater threats to high‐elevation conifer forest and riparian areas underscore their value for conservation. Significant populations of many breeding bird species, including some that are of concern or were not known to occur regionally or in mountain ranges we surveyed, highlight the importance of conservation efforts in this area of Mexico.     

A field study of Geoffroy's tamarin (Saguinus geoffroyi) in Panama

A 3-month field study was conducted in Panama to determine presence and relative abundance of Saguinus geoffroyi, the Geoffroy's tamarin, and status of its habitat (see Acknowledgments for taxonomic note). This primate has a wide geographical distribution in eastern Panama; however, local distribution is highly variable. Tropical forest habitat is rapidly being converted for agriculture and timber. Areas where human access was strictly limited showed tamarin densities significantly greater than in less protected areas. Disturbance has a distinct impact on population densities. There may also be a relationship between tamarin abundance and specific types of vegetation. Future actions regarding the conservation of S. geoffroyi and its habitat are recommended.     

Burrow densities and nest site preferences of petrels (Procellariidae) at the Prince Edwards Islands

Summary The nest-site preferences of six burrowing petrel species, Salvin's prion Pachyptila vittata salvini, blue petrel Halobaena caerulea, great-winged petrel Pterodroma macroptera, Kerguelen petrel Pterodroma brevirostris, soft-plumaged petrel Pterodroma mollis and white-chinned petrel Procellaria aequinoctialis, in the northeastern part of Marion Island (Prince Edward Island group, southern Indian Ocean) were analyzed by step-wise multiple regression. The nest-site characteristics measured were slope angle, soil depth and moisture content, percentage cover by stones or boulders and percentage cover by each of seven major plant species. The major nest-site preferences were: exposed areas with shallow soil (Salvin's prion); steep coastal slopes (blue petrel); sheltered well-drained slopes with deep soil (great-winged petrels); wet areas along drainage lines (Kerguelen petrel); steep slopes (soft-plumaged petrel); and areas with deep soil (white-chinned petrel). Similar species showed no significant avoidance of nest sites where there were burrows of potential competitors but did tend to nest spread out over different habitats. Burrow densities were determined in six habitat and seven vegetation types. Salvin's prion was the most abundant species (81% of burrows, with a maximum density of 279 burrows ha^-1) and used both burrows and natural cavities for nesting. For all species combined, burrow densities at Marion Island were lower than in comparable habitats and vegetation types at neighbouring Prince Edward Island. Depredation by feral house cats Felis catus, absent from Prince Edward Island, is assumed to be largely responsible for this difference.     

Diversity, regeneration status and socio-economic importance of the vegetation in the islands of Lake Ziway, south-central Ethiopia

This study was conducted in the islands of Lake Ziway located in the main Ethiopian Rift Valley in south-central Ethiopia. Its main objective was to investigate the diversity, regeneration status, socio-economic importance and the factors that cause degradation of the plant resources in the islands. A total of 73 relevés, measuring 20×20 m, were established along line transects laid from the central part of each island to the lake edge in eight aspects. Herbaceous species were sampled by using a 2×2 m sub-relevé laid within each relevé. In each relevé, the cover/abundance of each species was estimated, woody species were counted, diameter at breast height and height of trees and shrubs and the environmental variables altitude, slope, aspect and position were measured. Participatory Rural Appraisal was employed to generate the socio-economic information. A total of 141 species belonging to 113 genera and 55 families were identified, of which 18.4% were trees, 21.3% trees/shrubs, 12.1% shrubs, 3.5% lianas, 4.3% herbaceous climbers and 40.4% herbs. The overall Shannon diversity and evenness of woody species in the islands were 2.60 and 0.62, respectively. The number of species on the islands correlated with island's size, habitat diversity and degree of human disturbance. The similarity in species composition between the islands was low, indicating that each island has its own unique flora. Nine plant communities were recognized and described. The total density and basal area of the vegetation were 2979 individuals ha⁻¹ and 191 m² ha⁻¹, respectively. The importance value index and the diameter and height class distribution revealed that some species are threatened and need the highest priority for conservation. The socio-economic survey showed that the island communities are highly dependent on the natural vegetation for various purposes. On the other hand, the islanders have maintained the soil and vegetation resources for centuries through their indigenous resource management systems and practices. Human population growth coupled with farmland expansion, soil erosion, free grazing and cutting trees for various purposes are the major threats to the vegetation resources in the islands. The implications of the results are discussed and recommendations are suggested for conservation, management and sustainable utilization of the fragile island ecosystems.     

Identifying multiscale habitat factors influencing koala (Phascolarctos cinereus) occurrence and management in Ballarat, Victoria, Australia

Summary   Modelling for the conservation of koala ( Phascolarctos cinereus ) populations has primarily focused on natural habitat variables (e.g. tree species, soil types and soil moisture). Until recently, limited consideration has been given to modelling the effects of the landscape context (e.g. habitat area, habitat configuration and roads). Yet, the combined influence of natural habitats and anthropogenic impacts at multiple spatial scales are likely to be important determinants of where koala populations occur and remain viable in human-modified landscapes. The study tested the importance of multiscale habitat variables on koala occurrence in Ballarat, Victoria, Australia. The models focused at three spatial scales: site ( <  1 ha), patch (1–100 ha), and landscape (100–1000 s ha). Logistic regression and hierarchical partitioning analyses were used to rank alternative models and key explanatory variables.
The results showed that an increased likelihood of koala presence in fragmented landscapes in the urban–forest interface (as opposed to larger blocks of forest habitat) can best be explained by the positive effects of soil fertility and the presence of preferred koala tree species in these fragmented areas. If koalas are to be effectively conserved in Ballarat, it is critical to (i) protect remaining core areas of high-quality habitat, including regenerating areas; (ii) protect scattered habitat patches which provide connectivity; and (iii) develop and implement habitat restoration programmes to improve habitat connectivity and enhance opportunities for safe koala movement between habitat patches intersected by main roads.     

Abundance and habitat preferences of the southernmost population of mink: implications for managing a recent island invasion

Since 2001 invasive American mink has been known to populate Navarino Island, an island located in the pristine wilderness of the Cape Horn Biosphere Reserve, Chile, lacking native carnivorous mammals. As requested by scientists and managers, our study aims at understanding the population ecology of mink in order to respond to conservation concerns. We studied the abundance of mink in different semi-aquatic habitats using live trapping (n = 1,320 trap nights) and sign surveys (n = 68 sites). With generalized linear models we evaluated mink abundance in relation to small-scale habitat features including habitats engineered by invasive beavers (Castor canadensis). Mink have colonized the entire island and signs were found in 79% of the surveys in all types of semi-aquatic habitats. Yet, relative population abundance (0.75 mink/km of coastline) was still below densities measured in other invaded or native areas. The habitat model accuracies indicated that mink were generally less specific in habitat use, probably due to the missing limitations normally imposed by predators or competitors. The selected models predicted that mink prefer to use shrubland instead of open habitat, coastal areas with heterogeneous shores instead of flat beaches, and interestingly, that mink avoid habitats strongly modified by beavers. Our results indicate need for immediate mink control on Navarino Island. For this future management we suggest that rocky coastal shores should be considered as priority sites deserving special conservation efforts. Further research is needed with respect to the immigration of mink from adjacent islands and to examine facilitating or hampering relationships between the different invasive species present, especially if integrative management is sought.     

Genetic variation and structuring in the threatened koala populations of Southeast Queensland

Habitat fragmentation can act to cause reproductive isolation between conspecifics and undermine species’ persistence, though most studies have reported the genetic condition of populations that have already declined to a very small size. We examined genetic diversity within the vulnerable, declining koala (Phascolarctos cinereus) population in Southeast Queensland, Australia to determine the genetic impact of ongoing threatening processes. Five hundred and twelve koalas from ten Southeast Queensland Local Government Areas on the mainland and one island were genotyped at six polymorphic microsatellite loci. Based on Bayesian cluster analysis incorporating spatial data, the regional koala population was subdivided into six clusters, with location of major roads and rivers appearing to be consistent with being barriers to gene flow. The distribution of mtDNA control region haplotypes identified distinct coastal and inland clades suggesting that historically there was gene flow between koalas along the coast (though little interchange between coastal and inland animals). In contrast, koalas from the Koala Coast (Brisbane City, Logan City and Redland Shire) were shown by microsatellite analysis to be genetically distinct from adjacent areas. It is likely, therefore, that more recent reductions in population size and restricted gene flow through urbanisation have contributed to the genetic differentiation of koalas in the Koala Coast region.     

The distribution,abundance, and the effects of fire on mound building termites (Trinervitermes and Cubitermes spp., Isoptera: Termitidae) in northern guinea savanna West Africa

Summary Termite mound densities in typical guinea savanna, Detarium, and grassland (boval) habitats in northern guinea savanna were determined by random quadratting of 2–3 sites in each habitat (100, 10x10 m quadrats per habitat). Dominant species in guinea savanna were T. geminatus (46 mounds ha^-1) and T. oeconomus (21 mounds ha^-1), in Detarium T. geminatus (59 mounds ha^-1) and C. curtatus (45 mounds ha^-1) and in boval C. curtatus (72 mounds ha^-1) and T. geminatus (22 mounds ha^-1). Only C. curtatus densities and total densities differed significantly between sites within habitats, but all species differed significantly in abundance between habitats. The composition of each community was related to general environment but no particular environmental variable was shown to be a major determinant of termite distribution. Evidence for the limitation of termite populations was obtained from indirect evidence of competition between colonies in Detarium, and by experimental manipulation of fire regimes in the typical guinea savanna habitat. Harvester termites increased four-five fold over two years in fire-protected plots as a result of increased food supplies. Total termite densities in the fire-protected community equilibrated to the new population density (100 mounds ha^-1) after only two-three years.     

Correlates of Common Buzzard Buteo buteo density and breeding success in the West Midlands

Buzzard density and breeding success in relation to habitat and Rabbit Oryctolagus cuniculus abundance was studied in the West Midlands from 1994 to 1996. We found densities of 81 and 22 territorial pairs per 100 km² in two areas 40 km apart; the former is the highest density yet recorded in Europe. High Buzzard breeding densities were associated with high proportions of unimproved pasture and mature woodland within estimated territories. Buzzards laid earlier clutches at lower altitudes and with high proportions of unimproved pasture close to nests. Large clutches and high numbers of fledged young were associated with high Rabbit abundance close to nests. Most nest failures occurred during incubation and were probably mainly due to corvid predation. Brood reduction was associated with low proportions of deciduous woodland close to nests and small clutch sizes, although the causes of chick mortality were uncertain. Rabbits were the main prey item found at nests with passerines, especially young corvids, also appearing frequently.     

Inbreeding and disease avoidance in a free‐ranging koala population

Habitat destruction and fragmentation are increasing globally, forcing surviving species into small, isolated populations. Isolated populations typically experience heightened inbreeding risk and associated inbreeding depression and population decline; although individuals in these populations may mitigate these risks through inbreeding avoidance strategies. For koalas, as dietary specialists already under threat in the northern parts of their range, increased habitat fragmentation and associated inbreeding costs are of great conservation concern. Koalas are known to display passive inbreeding avoidance through sex‐biased dispersal, although population isolation will reduce dispersal pathways. We tested whether free‐ranging koalas display active inbreeding avoidance behaviours. We used VHF tracking data, parentage reconstruction, and veterinary examination results to test whether free‐ranging female koalas avoid mating with (a) more closely related males; and (b) males infected with sexually transmitted Chlamydia pecorum. We found no evidence that female koalas avoid mating with relatively more related available mates. In fact, as the relatedness of potential mates increases, so did inbreeding events. We also found no evidence that female koalas can avoid mating with males infected with C. pecorum. The absence of active inbreeding avoidance mechanisms in koalas is concerning from a conservation perspective, as small, isolated populations may be at even higher risk of inbreeding depression than expected. At risk koala populations may require urgent conservation interventions to augment gene flow and reduce inbreeding risks. Similarly, if koalas are not avoiding mating with individuals with chlamydial disease, populations may be at higher risk from disease than anticipated, further impacting population viability.