Persistence, size, trends and productivity in populations of two Critically Endangered Indonesian cockatoos

The aim of this thesis was to understand patterns of persistence, size, trends and productivity in populations of two Critically Endangered and heavily traded Indonesian cockatoos: the Yellow-crested Cockatoo Cacatua sulphurea and Citron-crested Cockatoo Cacatua citrinocristata. The Yellow-crested Cockatoo was formerly common and widespread on many islands of Wallacea. Its former subspecies on Sumba, the Citron-crested Cockatoo, was recently elevated to species level. After dramatic declines information on the remnant populations of both species is essential to guide future conservation management. A challenge with species that have disappeared from most of their range is to identify correlates of local persistence. The Yellowcrested Cockatoo and Citron-crested Cockatoo have undergone catastrophic declines due to habitat loss and especially trapping. The former is now extinct in much of its range across Indonesia while the latter has lost substantial numbers and some of its old sites on Sumba. Of 144 sites supporting cockatoos in 1950 only 76 did so in 2015. I compared socio-ecological conditions between the occupied and unoccupied sites, using 'random forests'. Tree cover, sparse human densities and low road densities promoted cockatoo survival but site-specific conditions (e.g. sacred groves, NGO activities) were also important. These local influences offer exciting possibilities for low-cost conservation prescriptions tailored to individual sites. One of the few Yellow-crested Cockatoo populations still numbering >100 individuals survives on Komodo Island. Distance sampling was combined with density surface modelling (DSM) to predict local densities and estimate total population size for this island. The population estimate of 1,113 (95% CI: 587–2,109) individuals on Komodo was considerably larger than previous conservative estimates. Coincidence between the DSM and a set of independent cockatoo observations was high (93%). Standardised annual counts by national park staff showed increases in cockatoo records from <400 in 2011 to ~650 in 2017. Taken together, the results indicate that Komodo National Park, alongside and indeed because of preserving its iconic Komodo Dragons Varanus komodoensis, is succeeding in protecting a significant population of Indonesia's rarest cockatoo species. This study's findings highlight the potential of DSM for locating abundance hotspots and estimating global population size in a range of threatened taxa. Although the importance of long-term monitoring is widely recognised, very few tropical bird species have been monitored over the span of 25 years. A multi-species distance sampling survey from 1992 was replicated in 2017, and present data on five parrot species and a hornbill, with three threatened island endemics, Citron-crested Cockatoo Cacatua citrinocristata (CR), Sumba Eclectus Eclectus cornelia (EN) and Sumba Hornbill Rhyticeros everetti (EN), two restricted-range species, Great-billed Parrot Tanygnathus megalorynchos and Marigold Lorikeet Trichoglossus capistratus, and one Wallacean-Papuan species, Red-cheeked Parrot Geoffroyus geoffroyi. Densities of the three large parrots and the hornbill in 2017 were similar to 1992 but densities of the smaller Red-cheeked Parrot and Marigold Lorikeet declined significantly in the same time span. Quantity of forest on Sumba is assessed for both years, presence data and local density estimates to gauge island-wide population sizes. The Marigold Lorikeet may need a re-assessment of its global Red List status. The uncertainty in trends for the threatened cockatoo, eclectus and hornbill is of concern as they show no definite sign of sustainable recovery from the extensive trapping of past decades. Knowledge of breeding success and its limiting factors is crucial in assessing species' conservation needs. As hole-nesters, parrots are particularly influenced by the availability of suitable cavities and low breeding output. On Sumba, the Citron-crested Cockatoo has to compete with an unusually rich hole-nesting bird community affected by forest loss. Ninety-five nesting cavities of cockatoos were monitored including competitors and potential nest-predators, over one to four breeding seasons, using a combination of camera-traps, direct checks on nest contents, and observations from the ground. Competition for suitable cavities was intense among three large parrot species, two owls and a hornbill. The Endangered Sumba Hornbill dominated observed direct confrontations and was the most frequent visitor to active parrot nests, suggesting a further role as a potential nest-predator. Cockatoos prospected many cavities but rarely then attempted to nest. At the few cavities where cockatoos did breed, predation pressure was likely low, and observed success rate high (10 successful of 15 nests). Intense competition for cavities suggests a shortage of suitable nest-sites, the need to preserve old hole-bearing trees and a role for nestboxes. Both studied cockatoo species would benefit from targeted local awareness-raising and law enforcement, with the whole endeavour backed up by longer-term forest restoration. The recent split of the Citron-crested Cockatoo leaves the resultant two species at higher risk of extinction than when they were assessed combined. The population on Sumba remains under pressure from illegal trapping, habitat loss, nest site competition and appears to have low productivity. Only two of the six Yellow-crested Cockatoo subspecies retain wild populations > 300 individuals but for each subspecies recovery is still possible, if conservation management tailored to each location is implemented, including public awareness programmes, provision of nestboxes, logistical and capacity building support, habitat protection and law enforcement

Breeding ecology of the Seychelles Black Parrot Coracopsis barklyi

Knowledge of breeding ecology is required for many conservation interventions. The Seychelles Black Parrot Coracopsis barklyi, endemic to the island of Praslin, is vulnerable to extinction. We aimed to improve understanding of C. barklyi breeding ecology to aid conservation planning. We present the results of four years of research, including nesting cavity characteristics and availability, reproductive success, breeding parameters, parental behaviour and reproductive strategy. Thirty-six breeding attempts were studied over the four seasons. Nests were mainly located in Coco de Mer palms Lodoicea maldivica. Deeper cavities with more canopy cover were preferred. There may be a shortage of high-quality nesting cavities in intensive breeding seasons. Average clutch size was 2.2 eggs, incubation period was c. 15 d and egg fertility was 71%. Rats were key nest predators, causing the failure of up to 33% of breeding attempts. The probability of nest success was 53%. At least 57% of fledglings survived their first year. This species breeds cooperatively and practices a highly unusual side-by-side copulation. We discuss the implications of the results in the context of former, ongoing and potential conservation measures for C. barklyi including translocation, invasive species management, nest box provisioning, habitat restoration and further research.Keywords: avian breeding ecology, breeding success, chick growth, island endemic species, nesting cavity selection, palm forestOSTRICH 2014, 85(3): 255–26

Insights into the feeding ecology of the Seychelles Black Parrot Coracopsis barklyi using two monitoring approaches

Feeding ecology is an important factor for the survival of a species and knowledge of its parameters is a prerequisite for successful conservation work. In this study we describe the feeding ecology of the endemic Seychelles Black Parrot Coracopsis barklyi on Praslin, Seychelles, the only island on which this parrot is resident. We compared two methods to evaluate feeding choices: incidental observations and feeding walks on 25 transects in all habitat types. Black parrots fed on 46 different species, bringing the total number of known food plants to 53 species. They predominantly consumed endemic and native species (58% of observed feeding bouts), mainly their fruit pulp (in 68% of feeding bouts), followed by buds (15%) and seeds (37%) with occasional observations of leaves, bark and scale insects. The incidental method rendered many more observed bouts than the transect approach and the ratios of consumed species differed between methods but the transect results are regarded as more representative. The incidental method is not suitable for quantitative conclusions but complements the transect method, providing information about rarely occurring feeding events.Keywords: Coracopsis barklyi, feeding ecology, Indian Ocean, palm forest, parrots, Seychelles Black ParrotOSTRICH 2014, 85(3): 245–25

Stable isotope values of auks on an annual cycle.

<p>δ¹³C and δ¹⁵N values (mean ± SE) of blood (breeding), back-feathers (post-breeding) and throat feathers (pre-breeding), of adult razorbills (blue), common guillemots (red) and Brünnich’s guillemots (black).</p

Spatial distribution of auks during September and April.

<p>50% (solid) and 95% (dashed) kernel distribution of razorbills (n = 9, blue), common guillemots (n = 8, red) and Brünnich’s guillemots (n = 6, black) during the first half of September (left panel) and April (right panel). Razorbills left the east coast of North America at the end of April, thus the activity area north of 50^° N represents the period from 24^th of April and onwards. The breeding colony is marked with a yellow star.</p

Research and conservation of the larger parrots of Africa and Madagascar: a review of knowledge gaps and opportunities

Parrot populations in Africa and Madagascar are declining and the need for conservation actions to address threats is increasingly recognised. Effective conservation requires a robust knowledge base on which decisions over appropriate actions can be made, yet at present there is no current and readily accessible synthesis of the status of populations, the threats they face and knowledge gaps. Here we begin to address this shortfall for the larger species in the region belonging to the genera Coracopsis, Poicephalus, Psittacus and Psittacula. We review developments since the production of the IUCN Parrot Action Plan published in 2000, identify areas where critical knowledge is lacking and highlight opportunities to address them. While advances have been made over the last decade, progress has not been evenly spread, with a strong bias towards populations in southern Africa. To date much research has focused on describing aspects of ecology and behaviour and there remains a need for studies determining the current status of populations and the factors limiting distributions and abundance. This review aims to provide a basis upon which progress towards an improved understanding of the conservation needs of the larger parrots of Africa and Madagascar can be made.Keywords: conservation priorities, conservation status, Coracopsis, Poicephalus, Psittacula, PsittacusOSTRICH 2014, 85(3): 205–23