Calyptorhynchus Banksii Research Articles

Clutch size, incubation and nestling periods, and age estimation of nestling Red-tailed Black Cockatoos Calyptorhynchus banksii escondidus in the Western Australian wheatbelt

ABSTRACT The breeding ecology of the Red-tailed Black Cockatoo Calyptorhynchus banksii escondidus was studied in the northern wheatbelt of Western Australia from the austral spring of 1974 to the end of 1981. The usual clutch was one egg, but 8 of 465 clutches were of two eggs, none of which produced two fledglings. The incubation period was 29 days, similar to that of other species of black cockatoo with similar body mass. The nestling period was 80-84 days, nearly 17% longer than the similarly-sized Carnaby's Cockatoo C. latirostris. The ages of nestling Red-tailed Black Cockatoos may be estimated by comparison with photographs taken of nestlings of known age or estimated more precisely from the length of the nestling's folded wing. Aging nestlings enables the calculation of laying and hatching dates.

Food and movements of the Red-tailed Black Cockatoo Calyptorhynchus banksi escondidus in the Western Australian wheatbelt

ABSTRACT The diet and movements of a breeding population of the Red-tailed Black Cockatoo Calyptorhynchus banksi escondidus was studied between spring 1974 and the end of 1981 at Nereeno Hill in the northern wheatbelt of Western Australian. The birds fed almost exclusively on the seed of Double Gee Emex australis, an introduced, prolific, agricultural weed. When incubating and raising young nestlings, parents foraged within 5 km of their breeding area. However, once their nestlings were older, they often foraged more than 20 km from their nest hollows, commuting over an hour in the early morning and again in the evening. In doing so, they passed over available food, to join large, non-breeding, foraging flocks. Once the birds finished breeding they foraged widely in large flocks of over 1000 birds, up to 200 km from their breeding area. The dependence on the seed of an agricultural weed for food has allowed the birds to increase their distribution and abundance, but is a potential threat to the cockatoos, as any control measure that severely reduces the density of Double Gee may adversely impact on the distribution of the cockatoos in the southern part of their range.

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.

Forest specialist species in the urban landscape: Do different levels of urbanization affect the movements of Forest Red-tailed Black Cockatoos (Calyptorhynchus banksii naso)?

Rycken, S. J. E., K. S. Warren, L. Yeap, R. Donaldson, P. Mawson, R. Dawson, and J. M. Shephard. 2022. Forest specialist species in the urban landscape: Do different levels of urbanization affect the movements of Forest Red-tailed Black Cockatoos (Calyptorhynchus banksii naso)? Avian Conservation and Ecology 17(1):11. https://doi.org/10.5751/ACE-02061-170111

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.

Application of tri-axial accelerometer data to the interpretation of movement and behaviour of threatened black cockatoos

Abstract Context Carnaby’s (Calyptorhychus latirostris), Baudin’s (Calyptorhynchus baudinii) and forest red-tailed black cockatoos (Calyptorhynchus banksii naso) are threatened parrot species endemic to south-western Australia. Behavioural monitoring has previously involved direct observation, which has proven challenging because of their cryptic nature, the type of habitat they move through and their speed of movement. The development of a model to accurately classify behaviour from tri-axial accelerometer data will provide greater insight into black cockatoo behaviour and ecology. Aims To develop an automated classifier model to classify accelerometer data from released black cockatoos to determine behaviour and activity budgets for three species of black cockatoo. Methods In the present study, we attached tri-axial accelerometers, housed in GPS tags, to four Carnaby’s cockatoos, three forest red-tailed black cockatoos and two Baudin’s cockatoos in captive care, undergoing rehabilitation for release back to the wild. Accelerometer data from these birds was coupled with 19 video files of the birds’ behaviour when flying, feeding and resting, to develop an automated behaviour classifier. The classifier was then used to annotate accelerometer data from 15 birds released after successful rehabilitation and to calculate activity budgets for these birds post-release. Key results We developed a classifier able to identify resting, flying and foraging behaviours from accelerometer data with 86% accuracy, as determined by the percentage of observed behaviours correctly identified by the classifier. The application of the classifier to accelerometer data from 15 released cockatoos enabled us to determine behaviours and activity budgets for all three species of black cockatoo. Black cockatoos spent most of their time at rest, followed by foraging with a short period of time flying. Conclusions Application of the classifier to data from released birds gives researchers the ability to remotely identify patterns of behaviour and calculate activity budgets. Implications Combining behaviour and activity budgets with location data provides useful insight into cockatoo movement, distribution, and habitat use. Such information is important for informing conservation efforts and addressing outstanding research objectives. Further studies including larger sample sizes of Baudin’s and forest red-tailed black cockatoos and comparing behaviour and activity between birds in breeding and non-breeding areas are warranted.

Foraging enrichment alleviates oral repetitive behaviors in captive red-tailed black cockatoos (Calyptorhynchus banksii).

The relationship between inadequate foraging opportunities and the expression of oral repetitive behaviors has been well documented in many production animal species. However, this relationship has been less-well examined in zoo-housed animals, particularly avian species. The expression of oral repetitive behavior may embody a frustrated foraging response, and may therefore be alleviated with the provision of foraging enrichment. In this study, we examined the effect of different foraging-based enrichment items on a group of captive red-tailed black cockatoos who were previously observed performing oral repetitive behavior. A group of six cockatoos were presented with five foraging enrichment conditions (no enrichment (control), sliced cucumber, fresh grass, baffle cages, and millet discs). Baseline activity budgets were established over a 10-day preintervention period and interventions were then presented systematically over a 25-day experimental period. This study demonstrated that the provision of foraging interventions effectively increased the median percentage of time spent foraging compared to control conditions (range, 5.0-31.7% across interventions vs. 5.0% for control), with two of the interventions; grass and millet discs, significantly decreasing the expression of oral repetitive behaviors (control = 16.6 vs. 8.3% for both grass and millet discs). Finally, a rapid-scoring method utilized by zookeepers during the study proved to be a useful proxy for the amount of time the cockatoos spent interacting with the foraging interventions and overall time spent foraging.

Museum specimens provide reliable SNP data for population genomic analysis of a widely distributed but threatened cockatoo species.

Natural history museums harbour a plethora of biological specimens which are of potential use in population and conservation genetic studies. Although technical advancements in museum genomics have enabled genome-wide markers to be generated from aged museum specimens, the suitability of these data for robust biological inference is not well characterized. The aim of this study was to test the utility of museum specimens in population and conservation genomics by assessing the biological and technical validity of single nucleotide polymorphism (SNP) data derived from such samples. To achieve this, we generated thousands of SNPs from 47 red-tailed black cockatoo (Calyptorhychus banksii) traditional museum samples (i.e. samples that were not collected with the primary intent of DNA analysis) and 113 fresh tissue samples (cryopreserved liver/muscle) using a restriction site-associated DNA marker approach (DArTseq™ ). Thousands of SNPs were successfully generated from most of the traditional museum samples (with a mean age of 44years, ranging from 5 to 123years), although 38% did not provide useful data. These SNPs exhibited higher error rates and contained significantly more missing data compared with SNPs from fresh tissue samples, likely due to considerable DNA fragmentation. However, based on simulation results, the level of genotyping error had a negligible effect on inference of population structure in this species. We did identify a bias towards low diversity SNPs in older samples that appears to compromise temporal inferences of genetic diversity. This study demonstrates the utility of a RADseq-based method to produce reliable genome-wide SNP data from traditional museum specimens.

Inference by exclusion in the red-tailed black cockatoo (Calyptorhynchus banksii).

Inference by exclusion is the ability to select a given option by excluding the others. When designed appropriately, tests of this ability can reveal choices that cannot be explained by associative processes. Over the past decade, exclusion reasoning has been explored in several non-human taxonomic groups, including birds, mainly in Corvids and Parrots. To increase our understanding of the taxonomic distribution of exclusion reasoning and, therefore, its evolution, we investigated exclusion performances in red-tailed black cockatoos (Calyptorhynchus banksii), an Australian relative of the Goffin cockatoo (Cacatua goffini), using a food-finding task. Cockatoos were required to find a food item hidden in 1 of the 2 experimenter's hands. Following training sessions in which they reliably selected the closed baited hand they had just been shown open, each individual was tested on 4 different conditions. Critical to demonstrating exclusion reasoning was the condition in which they were shown the empty hand and then offered a choice of both closed hands. The performance of all birds was above chance on all experimental conditions but not on an olfactory and/or cuing control condition. The results suggest that the birds might be able to infer by exclusion, although an explanation based on rule learning cannot be excluded. This first experiment in red-tailed black cockatoo highlights the potential of this species as a model to study avian cognition and paves the pathway for future investigations.

Effectiveness of biodiversity offsets: An assessment of a controversial offset in Perth, Western Australia

Environmental offsets are used increasingly as a conservation tool to balance demands of development and environment but there is little evidence that offsets are effective. Our study assessed the effectiveness of the offset package developed for the Roe Highway Extension, in Western Australia, for Carnaby's black cockatoo, red-tailed black cockatoo and southern brown bandicoot. Black cockatoos were accounted for in the offset requirements, while Southern brown bandicoots were accounted for in the mitigation requirements of the approval but not the offset requirements. The development was cancelled after partial clearing and has not been completed. Pre-development consultant surveys were examined in relation to the offset requirements. Fieldwork was conducted at the offset sites to ground-truth habitat qualities where possible. The offset package was then compared to the principles of Australian Commonwealth and State offset policies. We found the offset package did not completely satisfy Commonwealth or State offset requirements, showed inconsistencies with the policies and produced net loss of environmental value. The offset sites provided 64% of the black cockatoo habitat required by the Commonwealth offset requirements, and were of a lower quality. Similarly, undergrowth vegetation (<1 m; used by southern brown bandicoots) varied between the development and offset sites, indicating the offset proposal approval criteria ‘similar or better quality’ was not met. Like for like is not always required by offset legislation, but it was required in the approval criteria for this development project. The offset sites had previously been deemed unfit for development by the EPA, resulting in little additionality, a fundamental factor in ensuring true gains to compensate for the loss. To improve the suitability of offsets as a conservation tool we strongly encourage a checking process to confirm ecological outcomes of an offset, a contingency plan for if the offset doesn't provide sufficient ecological outcomes, greater consideration of requirements of species affected and stricter adherence to the wider principles of offsets. The use of biodiversity offsets is nearly inevitable given current development policies and processes; however, the application of offsets can be substantially improved to reduce further net loss of environmental value.

Development of a tag-attachment method to enable capture of fine- and landscape-scale movement in black-cockatoos

This study reports on a successful trial of a double-tag mounting protocol using both satellite and GPS tags on captive black-cockatoos (Forest Red-tailed Black-Cockatoo Calyptorhynchus banksii naso , Baudin’s Black-Cockatoo Zanda baudinii and Carnaby’s Black-Cockatoo Z. latirostris ). The aim of the study was to assess the feasibility and tolerance of a novel back-mount and a double-mount protocol combining a back- and tail-mount in black-cockatoos. We trialled solar 3D Global Positioning Systems (GPS) tags, standard solar and battery-operated GPS and Platform Terminal Transmitter (PTT) tags, and developed an attachment method to fit back-mounted solar-powered UvA-BiTS GPS tags to captive black-cockatoos. We investigated the effect of a variety of different types of tail-mounted satellite tags on the operational ability of the primary UvA-BiTS units and the feasibility of the double-mounted tag system with regard to tolerance by the birds. Our study determined that the combination of a 7.5-g UvA-BiTS GPS tag and 17-g Telonics TAV 2617 satellite tag was best tolerated by the birds and was the optimal tag system for use on birds to be released. This system enables capture of movement data to better understand the ecology of black-cockatoos, and identify critical feeding, roosting and breeding habitats, thereby informing conservation management initiatives to conserve these threatened species.

Development of a tag-attachment method to enable capture of fine- and landscape-scale movement in black-cockatoos

This study reports on a successful trial of a double-tag mounting protocol using both satellite and GPS tags on captive black-cockatoos (Forest Red-tailed Black-Cockatoo Calyptorhynchus banksii naso, Baudin’s Black-Cockatoo Zanda baudinii and Carnaby’s Black-Cockatoo Z. latirostris). The aim of the study was to assess the feasibility and tolerance of a novel back-mount and a double-mount protocol combining a back- and tail-mount in black-cockatoos. We trialled solar 3D Global Positioning Systems (GPS) tags, standard solar and battery-operated GPS and Platform Terminal Transmitter (PTT) tags, and developed an attachment method to fit back-mounted solar-powered UvA-BiTS GPS tags to captive black-cockatoos. We investigated the effect of a variety of different types of tail-mounted satellite tags on the operational ability of the primary UvA-BiTS units and the feasibility of the double-mounted tag system with regard to tolerance by the birds. Our study determined that the combination of a 7.5-g UvA-BiTS GPS tag and 17-g Telonics TAV 2617 satellite tag was best tolerated by the birds and was the optimal tag system for use on birds to be released. This system enables capture of movement data to better understand the ecology of black-cockatoos, and identify critical feeding, roosting and breeding habitats, thereby informing conservation management initiatives to conserve these threatened species.

Long-term passive acoustic monitoring of Western Australian cockatoos

Carnaby’s black cockatoos (Calyptorhynchus latirostris) and forest red-tailed black cockatoos (Calyptorhynchus banksii naso) are threatened avian fauna endemic to Southwestern Australia. Both species vocalize during various activities including flight, foraging, feeding, and breeding, and their vocalizations are known to differ by age and gender. In this study, passive acoustic monitoring is employed to assist with ongoing monitoring and recovery efforts. Autonomous acoustic recorders are installed at two locations—an urban setting in the Swan coastal plains and a bushland setting in the Perth hills district. The urban setting is a well-known roosting site for Carnaby’s cockatoos. Noise from frequent aircraft activity is a dominant feature at the bushland setting. Call repertoires, established using visual sighting information, are used in developing automatic recognition algorithms for efficient processing of long-term recordings. In addition to providing information on population estimates, distribution, and demographics, the project aims to study the differences in call characteristics between the urban and bushland settings and establish a framework for observing potential seasonal changes in calling behavior.

Characteristics of nest trees and nest hollows used by the forest red-tailed black cockatoo (Calyptorhynchus banksii naso) in south-west Western Australia: comments on Johnstone et al. (2013)

Johnstone et al. (2013) (Pacific Conservation Biology 19, 122–141) make a substantial contribution to the knowledge of the forest red-tailed black cockatoo (Calyptorhynchus banksii naso) (FRTBC), presenting data on nest hollows and nest tree attributes. They discuss the threats to the current and future breeding hollows and conclude that ‘we are facing a major crisis in southern forests’. Although there are sound reasons for concern over the conservation of cockatoo species, the imminence of a crisis is not established by the data presented. We provide spatial and management context and present data relevant to discussion of threats to FRTBC hollows in south-west Western Australia. The primary strategy for providing habitat across the publicly owned forests is reservation, which formally excludes timber harvesting from more than 50% (1.3 million ha) of the forest, informally protects a further 11%, and protects habitat trees within harvested areas. Timber harvesting in these forests generally involves partial cutting, which retains trees of a wide range of size and age classes. A realistic minimum age for trees bearing hollows used by FRTBC in the jarrah (Eucalyptus marginata) forest is ~120–150 years (trees diameters of 50–60 cm), well below the 209 years highlighted by Johnstone et al. (2013). Most nest hollows occur in intermediate-sized trees. Clustering of FRTBC nest trees was not demonstrated in their data but is worthy of further investigation. Improved estimates of nest tree availability and loss would provide perspective on the threats to FRTBC, as would knowledge of population size and age structure of the FRTBC. The protection of known nest trees and control of feral competitors, where possible, would benefit FRTBC.

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.

Hematologic and Plasma Biochemical Reference Values for Three Species of Black Cockatoos (Calyptorhynchusspecies)

Black cockatoos in southwest Western Australia face population declines as a result of habitat loss and fragmentation, poaching, competition with other species, vehicle strikes, and shootings. In this study, hematologic and plasma biochemical reference values were determined for 3 endemic Western Australian black cockatoo species: Carnaby's cockatoo (Calyptorhynchus latirostris) (n = 34), Baudin's cockatoo (Calyptorhynchus baudinii) (n = 22), and forest red-tailed black cockatoo (Calyptorhynchus banksii naso) (n = 22). Significant sex-related differences were detected in Carnaby's cockatoos, and differences were also found among the 3 species. The forest red-tailed black cockatoos showed a markedly greater eosinophil count than did the 2 white-tailed species. Blood values from samples obtained by different collection methods differed significantly for Carnaby's cockatoos, which indicates that anesthesia may affect analyte values and that collection methods should remain consistent. The results of this study will be useful for clinically evaluating wild black cockatoos that are undergoing rehabilitation for release and will provide baseline data for future investigations of free-living black cockatoo health.

Feeding activity of threatened black cockatoos in mine-site rehabilitation in the jarrah forest of south-western Australia

Land clearing threatens three black cockatoo species (forest red-tailed black cockatoo, (Calyptorhynchus banksii naso), Carnaby’s cockatoo (Calyptorhynchus latirostris), and Baudin’s cockatoo (Calyptorhynchus baudinii) endemic to south-western Australia, so revegetation is important to their recovery. Over three years we studied cockatoo activity in 7–14-year-old mine-site rehabilitation in the region’s jarrah (Eucalyptus marginata)–marri (Corymbia calophylla) forest to give the most detailed description to date of the use of rehabilitation by the birds. Pits varied floristically and structurally (despite similar rehabilitation prescriptions), but interior and exterior plots (100 m2) were similar within pits. Using feeding traces (e.g. chewed husks), and behavioural observations we confirmed feeding within eight years of revegetation. Plots containing feeding trace were similar to plots without, so factors determining black cockatoo feeding may not be apparent at small scales. Returning food resources reflected vegetation succession, with regenerating marri and fast-maturing proteaceous species providing most food. Carnaby’s cockatoo ate Banksia and Hakea seeds and Baudin’s cockatoo and the forest red-tailed black cockatoo consumed marri seeds. Banksia squarrosa, Hakea undulata, H. prostrata and marri were common foods in all years. Revegetation efforts elsewhere should consider these species, within the constraints of rehabilitation protocols addressing multiple aims.

Ecology of black cockatoos at a mine-site in the eastern jarrah-marri forest, western Australia.

Three threatened black cockatoos inhabit the Jarrah Eucalyptus marginata-Marri Corymbia calophylla forest of southwestern Australia: Baudin’s Cockatoo Calyptorhynchus baudinii, Carnaby’s Cockatoo C. latirostris, and Forest Redtailed Black Cockatoo C. banksii naso [FRTBC]. Their local ecology in relation to anthropogenic disturbance is poorly known, hampering effective conservation management. Therefore we studied their group size, site occupancy patterns, habitat use, and food plants at a mine-site and its surrounds in the eastern forest over three years. FRTBC showed similar group sizes and occupancy across seasons, suggesting year-round residency and no marked seasonality in movements and grouping patterns. In contrast, Carnaby’s Cockatoos were up to twice as abundant in spring and summer, indicating migrating or transient flocks and some year-round residents. Few Baudin’s Cockatoos were present in summer, but their abundance increased at other times. All three cockatoos were observed in modified or humanmade habitats such as mine-site rehabilitation, farm paddocks, and pine plantations. Carnaby’s Cockatoos used the broadest habitat range. We documented feeding on 16 plant species, with Carnaby’s Cockatoos eating at least 10. Examination of feeding residues as well as observations of behaviour were essential to obtain a complete picture of feeding. Current mine-site rehabilitation protocols provide food for all three black cockatoos within a decade and should continue to do so long-term if Marri is maintained in the seed mix. However, because climate change scenarios predict declining rainfall over much of southwestern Australia, the plant species used to revegetate mine-sites and other landscapes may need to be reconsidered. For areas that do not specify restoring a jarrah forest landscape, the selective use of exotic or non-endemic flora better adapted to lower rainfall conditions may be an option.

The breeding biology of the Forest Red-tailed Black Cockatoo Calyptorhynchus banksii naso Gould in south-western Australia. I. Characteristics of nest trees and nest hollows.

The Forest Red-tailed Black Cockatoo Calyptorhynchus banksii naso (FRTBC) is a large, iconic forest cockatoo, endemic to the south-west corner of Western Australia. It is currently listed as Vulnerable under the State Western Australian Wildlife Conservation Act and under the Commonwealth Environment Protection and Biodiversity Conservation Act. In this paper, we provide details of nest tree and nest hollow requirements based on details of hollows in 128 nest trees studied over 17 years. FRTBC are monogamous and pairs nest in tree hollows from 6.5–33 m above ground. Most nests are in very large and very old, mature Marri Corymbia calophylla, a long-lived endemic tree species, which is the most important nesting tree throughout the FRTBC range. Nest trees of all species had a mean circumference at breast height of 2.79 m, a mean estimated age of 222 years and a mean overall height of 20.24 m. Marri nest trees had an mean circumference at breast height of 2.76 m, a mean estimated age of 220 years (95% confidence limit 209–231 years) and an average overall height of 20.04 m. The rate of fall or loss of nest trees was high, c. 16.6% per decade. A wide range of hollow types, defined by position of the hollow in the tree, were found. Hollow aspects were also diverse. The mean height to a hollow was 14.49 m. Mean hollow depth was 1.44 m, mean floor space (the longest linear distance across the bottom of the hollow) was 33.2 cm and the mean hollow entrance area was 30 x 34 cm. FRTBC nests are typically, but not always, clustered in the landscape and social interactions within the flock are likely to play a part in the clustering of nests. Nest competitors, including feral European Honey Bee Apis mellifera, Carnaby’s Cockatoo Calyptorhynchus latirostris, Baudin’s Cockatoo C. baudinii and the Regent Parrot Polytelis anthopeplus were recorded using nest hollows once used by FRTBC. In the past Marri was harvested commercially, especially the largest and oldest trees, for timber and woodchips. In recent times the volume of Marri logs has been reduced due to a decline in markets e.g. between 2004 and 2010 a total of 95,436 m³ was harvested (K. Whitford, pers. comm.). Given the importance of large, old trees for FRTBC breeding habitat, conservation of these trees

The breeding biology of the Forest Red-tailed Black Cockatoo Calyptorhynchus banksii naso Gould in south-western Australia. II. Breeding behaviour and diet

Little is known of the breeding behaviour of the Forest Red-tailed Black Cockatoo Calyptorhynchus banksii naso (FRTBC), a large, iconic forest cockatoo, endemic to the south-west corner of Western Australia, currently listed as Vulnerable under the State Western Australian Wildlife Conservation Act and under the Commonwealth Environment Protection and Biodiversity Conservation Act. In this paper, we provide details of breeding behaviour of FRTBC based on observations throughout the year over 17 years, together with observations of diet and feeding behaviour over the same period. FRTBC are monogamous hollow-nesters. Breeding was recorded in all months, with peaks in autumn-winter (April– June) and spring (August–October), with few records in January and February. Breeding also varied between years, with little breeding in 1999, 2001 and 2008, but many observations in 2006 and 2009. Breeding occurred at times of fruiting of either of the principal feed trees, Jarrah Eucalyptus marginata or Marri Corymbia calophylla, so it does not depend solely on one or the other of these species. Courtship displays were noted at all times of the day, from before dawn at roost sites to dusk. In total, 205 breeding events were recorded, of which 69 (93%) of 72 nests had breeding confirmed on a second visit. Use of particular nest hollows varied considerably, with some used only once and some up to seven times. Only one egg is laid, which the female incubates for 29 to 31 days, before a nestling hatches weighing between 27 and 32 g. The female remains in the hollow during incubation and only leaves for a short period in the evening to be fed by the male, usually at dusk. The chicks are brooded for up to 10 days, after which the female leaves the nest between dawn and dusk. Pairs of birds appear to recognise each other by calls, not responding to calls by others in the area. Chicks only respond when the parent is heard. Chicks are fully feathered at 48 days. Fledgling success was estimated at 60%. Juveniles remain dependent on the adults 18 months to 2 years. Thirty-seven chicks were banded between 1997 and 2011. Juvenile-immature birds moved on average less than 3 km from their natal tree and older birds were observed moving up to 19 km. This suggests that FRTBC are generally sedentary. Immature birds took up to three times as long as their parents to open Jarrah or Marri nuts and eat the seeds. In recent years there has been an interesting change in foraging behaviour of birds in the northern Darling Range (adjacent to the Perth metropolitan area) with the FRTBC discovering and using a new food source, the introduced Cape Lilac Melia azedarach, and this species is of growing importance as food in the Perth region. In combination, the data on breeding biology and diet highlight the importance of identifying recruitment rates and food availability in managing populations of FRTBC.