Calyptorhynchus Lathami Research Articles

A decision support tool for habitat connectivity in Australia

Context Species connectivity mapping is a technically challenging task for conservation practitioners and nongovernment organisations to undertake as it requires experience in geographic information systems and often some computer programming. Aims We developed a decision support tool to provide spatial information and data on potential habitat connectivity and optimum connectivity pathways for a selection of forest-dependent vertebrate fauna in eastern and south-western Australia. Methods We systematically searched spatial data repositories for Australian spatial datasets for modelling connectivity. A least cost paths and patch connectivity approach was used to map potential habitat connectivity for (1) a single species – the glossy black cockatoo (Calyptorhynchus lathami) of South East Queensland, and (2) four species guilds – rainforest pigeons, gliding possums, the black cockatoos of south-western Western Australia and a landscape level forest connectivity. Optimum connectivity pathways were assessed for protection status. Key results In total 71 spatial datasets useful for habitat connectivity mapping were identified. Species and guild modelling found that the protection status for optimum connectivity pathways varied between 24.7% and 53.3%. A decision support mapping tool was then created to enable users to interactively explore the connectivity data and download the spatial datasets for further analysis. Conclusions The development of a decision support tool for mapping habitat connectivity in eastern and south-western Australia represents a useful platform for conservation practitioners as it provides valuable spatial information on potential connectivity pathways for forest-dependent vertebrate fauna. Implications The tool can aid in the prioritisation of conservation actions aimed at enhancing habitat connectivity and mitigating the impacts of habitat fragmentation on biodiversity in the two regions.

Impacts of bushfire on the Glossy Black-Cockatoo Calyptorhynchus lathami and its single food source in eastern Victoria

The Glossy Black-Cockatoo Calyptorhynchus lathami eats only unripened seeds extracted from green cones of Allocasuarina and Casuarina trees. This specialised feeding habit results in Glossy Black-Cockatoos leaving unique evidence of having fed in a tree (i.e. feeding sign). The frequency of feeding sign beneath Black Sheoak Allocasuarina littoralis trees in East Gippsland, Victoria, was used as an index of the presence of Glossy Black-Cockatoos before and after intense and widespread bushfires during the summer of 2019–2020. Species distribution models for the cockatoo and its major food tree in the region were used to define 175 survey points in forested parts of East Gippsland. Survey points were visited in mid 2019, to score the presence or absence of Black Sheoak and Glossy Black-Cockatoo feeding sign. Following the 2019–2020 bushfires, all sites where Black Sheoak was present pre-fire were revisited twice within the following 28 months to search for feeding sign and score the extent of regeneration of Black Sheoak. Across all sites, the frequency of sites with feeding sign effectively halved between the pre-fire survey and first post-fire survey, then halved again between the first and second post-fire surveys, an overall decline of 76%. After 25–28 months, regeneration of Black Sheoak, in the form of either basal sprouting of established trees or seed germination, was observed at 80.6% of burnt sites, with a tendency for highest rates of regeneration at lower-fire- severity sites and for suckering to be more common than seedlings at higher-fire-severity sites. These results highlight the vulnerability of the Glossy Black-Cockatoo to reductions in the availability of its specialised food. The greatest threat to food security stems from increased frequency and intensity of fire, as predicted for the region by climate change models.

Geology controls the distribution of a seed-eating bird: Feeding-tree selection by the glossy black-cockatoo Calyptorhynchus lathami.

Despite seed production being nutrient-limited, the influence of nutrient pathways on granivore distributions is unclear. This article examines the influence of geology and soil on the distribution of glossy black-cockatoos (Calyptorhynchus lathami), which feed almost exclusively on the kernels of casuarinas (Allocasuarina spp. and Casuarina spp.), and are selective about the trees in which they feed. To clarify the basis of this selection, Food Value (a measure of dry matter intake rate) and kernel nutrient content were compared between feeding and non-feeding trees of drooping sheoak (A. verticillata). Random forest modelling was then used to examine the influence of geology and soil chemistry on Food Value. Finally, logistic generalised additive modelling was used to examine the influence of geology on cockatoo feeding records across the range of black sheoak (A. littoralis) and forest oak (A. torulosa), drawing on a statewide dataset. Food Value-but not kernel nutrient concentrations-influenced feeding tree selection. Soils under drooping sheoak were nutritionally poor, with low nitrogen and phosphorus (despite high concentrations of these nutrients in the kernels), and characterised by two principal components: SALINITY (dominated by exchangeable magnesium and sodium, electrical conductivity, and sulphur) and ACIDITY (pH, iron, and aluminium). Random forest modelling showed that Food Value was highest on sedimentary rocks, with a high ACIDITY score, less than 18 meq 100 g-1 exchangeable calcium, and less than 4% soil organic carbon. The odds of cockatoos selecting casuarinas as feedings tree were three times higher on non-calcareous sedimentary rocks than on other rock types. Non-calcareous sedimentary rocks produce low-fertility, acid soils, which promote nitrogen-fixation by Frankia. I therefore conclude that glossy black-cockatoo distribution is controlled by the casuarina's symbiotic relationship with Frankia, which is ultimately controlled by geology; and that similar relationships may be responsible for the prevalence of several other species on low-fertility and/or acid soils.

The influence of surrounding habitat, behaviour and interspecific competition on nestbox use by endangered Glossy Black Cockatoos (Calyptorhynchus lathami halmaturinus)

Nestboxes have been deployed for parrots and cockatoos (Psittaciformes) worldwide, but there is limited evidence of their efficacy for these species. We examined the use of nestboxes by endangered South Australian Glossy Black Cockatoos Calyptorhynchus lathami halmaturinus, a habitat specialist that feeds almost solely on the seeds of Drooping Sheoak Allocasuarina verticillata trees, and investigated the factors that influenced nestbox use. Between 1998 and 2017, the mean annual proportion of nesting attempts that successfully fledged a chick was similar in nestboxes (52%, n = 547) and natural hollows (53%, n = 627). Nestbox use increased over time, which may reflect changes in the size and extent of the Glossy Black Cockatoo population over the study period. Nestboxes were more likely to be used by Glossy Black Cockatoos if they were close to the nest of another breeding pair and were not occupied by Yellow‐tailed Black Cockatoos Zanda funerea early in the breeding season. Nestboxes were also more likely to be used if they had been used in the previous breeding season, indicating nest‐site fidelity. The amount of A. verticillata feeding habitat in a 1‐km and 5‐km radius did not significantly influence nestbox use. Our study provides further evidence of the value of nestboxes to cockatoo conservation programmes, but also suggests that multiple factors other than local food availability influence uptake by a target species. Given that Glossy Black Cockatoos prefer to aggregate their nests, nestboxes for this species are most likely to be beneficial when they are used to expand the capacity of existing breeding areas or are clustered in the landscape. Our study demonstrates that well‐designed nestbox deployments should consider the preferred social groupings of cockatoos during the breeding season, and the location of competitor species, in order to maximize nestbox uptake.

Fledge or fail: Nest monitoring of endangered black-cockatoos using bioacoustics and open-source call recognition

Ecologists are increasingly using bioacoustics in wildlife monitoring programs. Remote autonomous sound recorders provide new options for collecting data for species and in contexts that were previously difficult. However, post-processing of sound files to extract relevant data remains a significant challenge. Detection algorithms, or call recognizers, can aid automation of species detection but their performance and reliability has been mixed. Further, building recognizers typically requires either costly commercial software or expert programming skills, both of which reduces their accessibility to ecologists responsible for monitoring. In this study we investigated the performance of open-source call recognizers provided by the monitoR package in R, a language popular among ecologists. We tested recognizers on sound data collected under natural conditions at nests of two endangered subspecies of black-cockatoo, the Kangaroo Island glossy black-cockatoo Calyptorhynchus lathami halmaturinus (n = 23 nests), and the south-eastern red-tailed black-cockatoo Calyptorhynchus banksii graptogyne (n = 20 nests). Specifically, we tested the performance of binary point matching recognizers in confirming daily nest activity (active or inactive) and nesting outcome (fledge or fail). We tested recognizers on recordings from nests of known status using 3 × 3-h recordings per nest, from early, mid and late stages of the recording period. Daily nest activity was correctly assigned in 61.7% of survey days analysed (n = 60 days) for the red-tailed black-cockatoo, and 62.3% of survey days (n = 69 days) for the glossy black-cockatoo. Fledging was successfully detected in all cases. Precision (true positive / true positive + false positive) of individual detections was 70.2% for the south-eastern red-tailed black-cockatoo and 37.1% for the Kangaroo Island glossy black-cockatoo. Manual verification of outputs is still required, but it is not necessary to verify all detections to confirm an active nest (i.e., nest is deemed active when true positives are identified). We conclude that bioacoustics combined with semi-automated post-processing can be an appropriate tool for nest monitoring in these endangered subspecies.

Vocal signals of ontogeny and fledging in nestling black-cockatoos: Implications for monitoring

ABSTRACT Bioacoustics offers new ways to monitor wildlife populations. Understanding vocal changes related to age can provide demographic data that are valuable but difficult to collect for threatened species. Here, we present the vocal signals of ontogeny and fledging in nestlings for two endangered black-cockatoos, the Kangaroo Island glossy black-cockatoo, Calyptorhynchus lathami halmaturinus, and the south-eastern red-tailed black-cockatoo, C. banksii graptogyne. Using sound recordings taken at wild nests (n = 3 for the red-tailed black-cockatoo; n = 7 for the glossy black-cockatoo), we examined changes in nestling vocalisations through to fledging. Nestlings vocalised from 4 weeks of age, but calls were soft and infrequent until about 6 weeks. Daily call rate increased significantly in the final week of nesting. Peak amplitude increased significantly with development for both subspecies. Call duration increased significantly for the glossy black-cockatoo. Likewise, low frequency increased significantly for the glossy black-cockatoo. Average entropy decreased significantly for both subspecies. Aggregate entropy decreased significantly for the red-tailed black-cockatoo. Fledging was associated with a loud and distinct vocal event. Together, these changes in call rate and structure, and the presence or absence of fledging vocalisations, provide useful ways to broadly categorise nest age and determine nest outcome from sound recordings.

The impact of fire on the quality of drooping sheoak (Allocasuarina verticillata) cones for the endangered Kangaroo Island glossy black-cockatoo (Calyptorhynchus lathami halmaturinus)

The Kangaroo Island glossy black-cockatoo (Calyptorhynchus lathami halmaturinus) is an endangered subspecies that feeds almost entirely on the kernels of drooping sheoak (Allocasuarina verticillata). Hence, it is highly susceptible to changes in the quantity or quality of A. verticillata. Fire has the potential to severely impact glossy black-cockatoo feeding habitat on the island, but since A. verticillata is serotinous, it is partially reliant on fire for regeneration. Here, we quantified the effects of time-since-fire (over a 60-year period) on cone quality for C. lathami halmaturinus. Cone quality in A. verticillata woodlands with a range of fire histories was examined using three measures of cone profitability: the ratio of seed-to-cone mass (Clout’s Index), the ratio of kernel-to-cone mass (Kernel Ratio) and the proportion of seeds containing kernels (Seed Fill). We then mapped the fire history of A. verticillata woodlands on Kangaroo Island before and after the 2019/20 bushfire season. We found that time-since-fire had a significant negative impact on Clout’s Index, as well as a negative but non-significant impact on Seed Fill and Kernel Ratio. This suggests that trees that have not experienced fire in over 60 years may have cones that are of lesser value to C. lathami halmaturinus. This is concerning, because up to 94% of A. verticillata woodlands not impacted by the 2019/20 bushfires are likely of a similar age class, having had no fire in over 60 years. Our findings highlight the need for ongoing assessment and management of critical habitat for this endangered subspecies.

Feeding profitability is associated with Glossy Black-cockatoo (Calyptorhynchus lathami ssp. lathami) feed tree selection

ABSTRACT Habitat modification and destruction are known to be responsible for declines in avian taxa. Specialist species such as the vulnerable Glossy Black-cockatoo (Calyptorhynchus lathami ssp. lathami) are particularly at risk due to the limited number of Casuarina and Allocasuarina species on which they feed, which is compounded by their propensity for selecting only specific individual feed trees within patches. This study aims to address the lack of understanding surrounding Glossy Black-cockatoo feeding ecology in southeast Queensland, Australia, by examining determinants of tree selection for Allocasuarina littoralis and A. torulosa. We conducted surveys to identify feed and non-feed trees of both Allocasuarina species, and differences between the physical and chemical characteristics of trees, cones, and seeds were investigated. We found that larger trees were preferentially foraged, with nutritional profitability as the primary factor governing tree selection. Feed tree cones had higher seed number and seed mass, with seeds containing higher levels of fatty acids and nutrients than non-feed tree cones. We conclude that further research should aim to delineate the factors contributing to these differences, alongside determining appropriate management strategies to support viable feeding habitat, which is most likely comprised of mixed age patches, capable of maintaining mature trees offering sufficient nutrient reward.

Nest‐associated vocal behaviours of the south‐eastern red‐tailed black cockatoo, Calyptorhynchus banksii graptogyne, and the Kangaroo Island glossy black cockatoo, C. lathami halmaturinus

AbstractAnimal vocalisations can signify diverse behavioural contexts, knowledge of which can be applied in bioacoustic monitoring programs. Australia’s endemic black cockatoos (Calyptorhynchus sp., family Cacatuidae) are highly vocal species that are threatened in many locations. In this study, we describe the nest‐associated vocal behaviours of two endangered subspecies of black cockatoo, the south‐eastern red‐tailed black cockatoo, C. banksii graptogyne and the Kangaroo Island glossy black cockatoo, C. lathami halmaturinus. Breeding success is limiting their recoveries and nest monitoring is challenging, but vocal recordings might provide valuable long‐term information hard to obtain otherwise. We recorded daily vocal activity at wild nests of both cockatoos using autonomous sound recorders. Combined with behavioural observations and video footage, we identified vocalisations characteristic of six behavioural contexts at nests: birds in flight, while perched, during begging (adult females), during courtship displays (adult males), when entering or sitting near to the nest hollow entrance (adult females), and from nestlings. Linear discriminant analysis on 12 acoustic measurements correctly classified 58.4% of calls of the red‐tailed black cockatoo (n = 907 calls from eight nests) and 62.9% of calls of the glossy black cockatoo (n = 1632 calls from 11 nests). In both subspecies, the female nest call and nestling calls are the most conspicuous vocal indicators of active nesting, and therefore should be considered for their bioacoustic potential. Other adult vocalisations indicate a range of behavioural contexts that could be informative for monitoring nesting behaviour, and its association to habitat features, in these endangered subspecies.

First records of nesting by South Australian Glossy Black- Cockatoos Calyptorhynchus lathami halmaturinus on eastern Kangaroo Island

The South Australian Glossy Black-Cockatoo Calyptorhynchus lathami halmaturinus is extinct on mainland Australia, and occurs only on Kangaroo Island. Between 1995 and 2016, a successful long-term Recovery Program more than doubled the population of this taxon on Kangaroo Island. This paper documents the first records of nesting by Glossy Black-Cockatoos on the Dudley Peninsula on eastern Kangaroo Island in 2015 and 2018, at a time when flock size had increased to 35 individuals in post-breeding counts on the Dudley Peninsula. Nesting there is evidence of the growth and expansion of the Glossy Black-Cockatoo population over the past 25 years, which is likely a result of conservation efforts. This new eastern nesting site expands the breeding range of this subspecies ~13 km east, and to the part of Kangaroo Island that is closest to mainland South Australia.

Wandering and Wildflowering: Walking with Women into Intimacy and Ecological Action

Wandering and Wildflowering: Walking with Women into Intimacy and Ecological Action

Improving population estimates of Glossy Black-Cockatoos (Calyptorhynchus lathami) using photo-identification

Site-based population estimates of the threatened Glossy Black-Cockatoo (‘GBC’; Calyptorhynchus lathami) are often calculated based on age and sex details from transect counts. However, these estimates do not distinguish individual birds, which may result in over-or under-estimation of the population. Two methods were used to estimate GBC populations in Mugii Murum-ban State Conservation Area, New South Wales: (1) the traditional transect method, and (2) a photographic method, which used plumage patterns (primarily the yellow facial feathers of females) and other supporting features to discriminate between foraging GBC family units. The second method has been used previously on Kangaroo Island, South Australia. A catalogue with a matrix of discriminating features was established based on the photographic method; this resulted in a higher population estimate than the transect method in two seasons (winter and spring), as well as providing an annual population estimate, and information on breeding dynamics and local movement of individual family units between foraging habitat. Recommendations for the application of the photographic method are provided. The method provides benefits at both the local scale (with more accurate site population estimates and information on population dynamics) and, with widespread adoption and national cataloguing, valuable knowledge on regional movement patterns and distribution.

Male sex-ratio bias in the endangered South Australian Glossy Black-Cockatoo Calyptorhynchus lathami halmaturinus

Sex biases in bird populations, particularly an excess of males, can threaten small, isolated populations by reducing reproductive rates. A skew in sex-ratio can be caused by (i) differential mortality at conception or hatching, (ii) differential survival to adulthood, or (iii) stochastic population processes. However, an observed sex-ratio bias can also result from a bias in census methods rather than a realised bias. Distinguishing between the two possibilities is critical to identifying the underlying causes. An excess of males has long been observed in the Kangaroo Island population of the endangered South Australian Glossy Black-Cockatoo (Calyptorhynchus lathami halmaturinus) (Psittaciformes: Cacatuidae), and our census data confirm this. Here, we use DNA-based sexing to test the accuracy of morphologically based nestling sex assignments in C. l. halmaturinus. We find that in all but one case, the DNA-based sexing was concordant with the sex assigned as nestlings, thus confirming the validity of nestling plumage-based sexing in a larger sample from this population. Our analysis of nestling sex data suggests that the adult sex-ratio is a function of a skew at fledging and not caused by higher rates of female mortality post fledging.

One fledgling or two in the endangered Carnaby's Cockatoo (Calyptorhynchus latirostris): a strategy for survival or legacy from a bygone era?

Of the five species of black cockatoo in the genus Calyptorhynchus, those species with red tail bands (Red-tailed Black Cockatoo and Glossy Black Cockatoo) lay clutches of only one egg and those with white or yellow tail bands (Carnaby's Cockatoo, Baudin's Cockatoo and Yellow-tailed Black Cockatoo) usually lay clutches of two. The breeding of the endangered Carnaby's Cockatoo has been studied from 1969 to 2012 at a number of localities throughout its range in south-western Australia within a region largely cleared for agriculture. When raising nestlings the species feeds on seeds of native vegetation, and there was a strong but not significant negative relationship between nesting success and percentage loss of native vegetation within 6 and 12 km of nest hollows. There was a significant negative relationship between the health of nestlings and percentage loss of native vegetation around nest hollows. While the usual clutch size is two, average clutch size tended to be lower in areas where much native vegetation has been cleared. While both eggs hatch in 77% of two-egg clutches, the species normally fledges only one young. However, the species is capable of fledging both nestlings from a breeding attempt. Sets of siblings are usually the product of older, more experienced females nesting in areas where more native vegetation has been retained. The conservation implications of these findings are discussed in the light of predicted changes to the climate of south-western Australia.

Restoration and management of callitris forest ecosystems in Eastern Australia: Simulation of attributes of growth dynamics, growth increment and biomass accumulation

Availability of quantitative information on growth increment, biomass accumulation and growth dynamics of fragmented and degraded forest ecosystems is a common challenge in restoration work. Ecological models of forest dynamics have the potential to provide a structure through which data, observations and assumptions can be combined and explored. The utility of such models, however, is often limited by lack of validation. In this paper we used growth data for 143,200 tree measurements, in 121 plots spanning up to 70 years of forest monitoring from uneven-aged mixed species callitris forests of Australia to test the Ecosystem Dynamics Simulator (EDS). These are among the least known and most degraded forest communities in Australia and are known habitat for threatened and rare fauna species including brush-tailed rock wallaby (Petrogale penicillata), glossy black-cockatoo (Calyptorhynchus lathami), grey falcon (Falco hypoleucos), golden-tailed gecko (Strophurus taenicauda) and others. We determined growth parameters for 26 woody species and applied these to the EDS to validate projected stand structure and growth. The model projections explained 93.9% (diameter at breast height (dbh)), 88.9% (basal area), 90.5% (stem density) and 88.6% (aboveground biomass) of the observed variation. To our knowledge, this is one of the most accurate validations of forest dynamics simulation achieved to date. Diameter growth rates for most species were <0.3cmyr−1 and reproduced well by the EDS, for all the species in the callitris forest communities. These growth rates indicate that exceptionally long periods will be required to restore the degraded or cleared forests to a mature state. Results can guide restoration and sustainable management of callitris forest ecosystems by providing projected measurable forest attributes to meet multiple goals, including harvesting of forest resources, carbon storage and conservation of biodiversity.

The influence of climate on Glossy Black-cockatoo reproduction

Glossy Black-cockatoos Calyptorhynchus lathami are dietary specialists, feeding almost exclusively on the seeds of Allocasuarina and Casuarina species. Their specialized diet makes them vulnerable to alterations in their food supply, and populations inhabiting variable environments are good candidates for identifying reproductive strategies that match output to the available food supply. I studied reproduction in a population of Glossy Black-cockatoos in central New South Wales, a region where rainfall varies substantially between years and which is subject to periodic drought. Seed production in the principal Glossy Black-cockatoo feed species in the region tracks rainfall, and as a consequence, the Glossy Black-cockatoo food resource fluctuates between years. I monitored nest success and population structure between 1997 and 2004, a period that included wet and dry years. There was a strong relationship between cockatoo productivity and rainfall in the preceding year. The principal determinant of annual productivity was the number of pairs attempting to breed. Increased aridity as a result of climate change will have negative consequences for inland populations of Glossy Black-cockatoos. Careful management of their habitat will be required if Glossy Black-cockatoo populations are to persist in the long term.

Use of artificial tree hollows by Australian birds and bats

Artificial tree hollows (nest or roost boxes) may be of considerable importance to the conservation and management of Australian hollow-using birds and microbats. This is suggested by recognition that the rate of collapse of hollow-bearing trees may exceed replacement in some landscapes. We review the published literature to synthesise current information on the use of artificial hollows by Australian birds and bats, and to provide guidance to future research and management. The use of artificial hollows has been documented in some detail for 15 native bird and eight microbat species. A range of hollow designs has been employed but there is a limited understanding of favoured designs. General designs (e.g. front-entry plywood boxes) have been used extensively by some species and should continue to be used until more effective designs are identified. Species tend to use artificial hollows that have entrance sizes just sufficient for their body size, and this should guide hollow design. Competitive interactions with a range of non-target species (native and non-native) may have a pronounced influence on artificial hollow use and must be considered in any management program involving artificial hollows. We highlight some design elements that may reduce interference by non-target species. Temperature inside artificial hollows may have a particular influence on their use by bats due to the role of microclimate in bat thermoregulation. Trials are needed to investigate this factor and to inform general approaches to positioning of artificial hollows. Several distinct management uses exist for artificial hollows, including assisting threatened species recovery, e.g. Kangaroo Island glossy black-cockatoo (Calyptorhynchus lathami halmaturinus) and orange-bellied parrot (Neophema chrysogaster). Artificial hollows offer an interim solution to hollow shortage but their full potential will only be realised when preferences for different designs are better understood. This will require a commitment to monitoring and should be conducted in an adaptive management context. Increased knowledge of the use of artificial hollows by Australian birds and bats should be of global relevance to the management of hollow-using species because it provides an independent test of ideas and strengthens any generalisations.

Food Value and tree selection by Glossy Black-Cockatoos Calyptorhynchus lathami

Food Value and tree selection by Glossy Black-Cockatoos Calyptorhynchus lathami

Casuarina ecology: factors limiting cone production in the drooping sheoak, Allocasuarina verticillata

Allocasuarina verticillata is an important species for biodiversity conservation on Kangaroo Island (South Australia) because it is the primary food source for the endangered glossy black-cockatoo, Calyptorhynchus lathami halmaturinus. Two potentially limiting factors, pollen and soil nutrients, were studied in the context of A. verticillata as foraging habitat for glossy black-cockatoos. Cone production was not limited by the amount of pollen available to female plants. The soils on which A. verticillata occurs on Kangaroo Island were low in nutrients. Available N, P and K were significantly increased via the application of slow-release fertiliser and the added nutrients resulted in a corresponding increase in the productivity of A. verticillata. The additional nutrients increased the number of cones produced on female branches, branch growth and potentially therefore, tree size. Since cone profitability appears to increase with tree size, the additional growth may also result in greater cone profitability in the long term. Adding slow-release fertiliser to small female A. verticillata trees and revegetation on sites with higher concentrations of soil nutrients would benefit the cockatoos. This is because other studies have shown that the cockatoos increase their foraging efficiency by cropping cones from large trees with greater cone profitability and branches with high densities of cones.

Aspects of Drooping Sheoaks (Allocasuarina verticillata) that influence Glossy Black-Cockatoo (Calyptorhynchus lathami halmaturinus) foraging on Kangaroo Island

Glossy Black-Cockatoos on Kangaroo Island, South Australia, rely primarily on the kernels contained in the seed-cones of the Drooping Sheoak (Allocasuarina verticillata) as their food source. This study expands on previous studies of Glossy Black-Cockatoos foraging on Kangaroo Island by examining selection of patches, trees, branches and cones. The Cockatoos appeared to maximise food intake per unit of foraging time by foraging in trees with higher seed-fill and kernel ratio. Although not conclusive, this study suggests breeding birds may be more selective of high seed-fill and kernel ratio than non-breeding birds. Within the canopy of the Sheoaks, the Cockatoos cropped cones from branches with high densities of cones present on them. The Cockatoos also showed a preference for foraging in large trees, which appears to reduce the number of movements they have to make between trees. This would both limit the energetic costs of foraging and limit exposure to predators.