Glossy black-cockatoo (Calyptorhynchus lathami) population, Riverina - endangered population listing
The Scientific Committee, established under the Threatened Species Conservation Act 1995, has made a Final Determination to list the Riverina population of the Glossy Black-Cockatoo Calyptorhynchus lathami (Temminck, 1807) as an ENDANGERED POPULATION in Part 2 of Schedule 1 of that Act.
NSW Scientific Committee - final determination
The Scientific Committee has found that:
1. The Glossy Black-Cockatoo Calyptorhynchus lathami is not listed on Part 1 of Schedule 1 of the Act and thus populations of Calyptorhynchus lathami are eligible for inclusion on Part 2 of Schedule 1 of the Act.
2. The Riverina population of Calyptorhynchus lathami is largely restricted to hills and low ridges where suitable assemblages of its food plant Drooping She-Oak Allocasuarina verticillata remain within the Narrandera Range and to the north-west in the Brobenah Hills, McPhersons Range, Cocoparra Range, Lachlan Range and Jimberoo State Forests, and the Naradhan Range. This population now occurs west of longitude 146° 40' E, within Cobar, Carrathool, Narrandera and Leeton Local Government Areas. This line runs through an area which is extensively cleared and this cleared area now seems to isolate the western population.
3. This population requires trees with suitable large hollows to breed, normally Grey Box Eucalyptus microcarpa or Dwyer's Gum Eucalyptus dwyeri, within close proximity to feeding habitat.
4. This population is disjunct and at the western edge of the range for the Glossy Black-Cockatoo in NSW. There is some evidence to suggest that individual birds move over considerable distances within the region. However, the genetic relationships between the Riverina population and the nearest easterly occurrences (The Charcoal Tank Nature Reserve near West Wyalong; Weddin Mountains and Conimbla National Parks; north from the Hervey Range to Goonoo State Forest and the Pilliga forests near Coonabarrabran) have yet to be clarified. There is some evidence that these western populations are more closely related to the Kangaroo Island subspecies Calyptorhynchus lathami halmaturinus than to more easterly populations indicating this population is of significant conservation value.
5. Anecdotal evidence from the Narrandera Range during the 1930s estimated aggregations of Glossy Black-Cockatoos to number in their hundreds, and flocks of more than 40 birds were not uncommon during the 1940s and 1950s. The greatest number recorded in the ranges in recent times is between 20 and 30 birds, following completion of the breeding season.
6. Habitat loss is seen as the major reason for the historical decline of this population. Much of the vegetation within the range of this species has been cleared, predominantly for agricultural purposes.
7. Threatening processes currently affecting this population include altered fire regimes and the grazing of Drooping She-Oak seedlings by rabbits, sheep and goats. These processes affect the availability of the critical food source of these birds.
8. Suitable breeding sites for the Riverina population of Glossy Black-Cockatoos have been affected by firewood collecting, and nest hollow pressure from predators and competitors, including feral European Honeybees and Brush-tailed Possums.
9. Glossy Black-Cockatoos are highly sought after in the avicultural trade. There is anecdotal evidence to suggest that illegal nest robbing has affected the Riverina population in the past. Nest hollows are often damaged or destroyed during this process.
10. The full impact of these threatening processes may not be observed for some years due to the long lifespan of these birds and the low rate of recruitment into the population.
11. In view of 2, 3, 4, 5, 6, 7, 8, 9 & 10 above the Scientific Committee is of the opinion that the Riverina population of the Glossy Black-Cockatoo, Calyptorhynchus lathami is eligible for listing as an endangered population because its numbers have been reduced to such a critical level that it is in immediate danger of extinction, it is disjunct and at the limit of its geographic range, and the population is of significant conservation value.
Proposed Gazettal date: 23/7/99
Exhibition period: 23/7/99 - 27/8/99