BOOBOOK
BOOBOOK
( Archived Extracts )
Issue 16 (1) & (2) of the magazine included the following articles :
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Threatened Raptors of Australia's Tropical Forests. (Reproduced here) |
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A World Review of Tropical Forest Raptors. |
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White Bellied Sea-Eagles in the Tamar River Catchment. |
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Brown Falcon Dive bombs Harmless Editor. |
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Sea Eagles and Oil 'Spills'. |
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Diet of Barn Owls. |
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Raptors on Sulawawesi (Indonesia). |
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Rehabilitation revisited. |
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Rehabilitation of Captive Bred Owls. |
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Feeding Ecology of Sharp-Shinned Hawks. |
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Re-establishment of tree nesting Peregrine Falcons in Europe. |
| Book Reviews : | |
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"Some time with Eagles and Falcons." |
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"Comprehensive guide to Raptor bio-medicine." |
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"Raptor Conservation Today." |
The following article is reproduced in its
entirety from Volume 16 of the ARA News.
Amongst threatened species worldwide, there is a great predominance of species inhabiting forest and islands (Halliday 1980; King 1981).Whilst this trend does not hold for threatened Australian birds in general (Ford 1989), it certainly does for threatened Australian raptors.
Australia has 4 species and 11 subspecies of raptor which have been classified as threatened using IUCN definitions (Garnett 1992). Three threatened species are endemic diurnal raptors and one is a large owl, while all but two of the 121 threatened subspecies are owls. One of the 15 threatened taxa occurs outside subcoastal, coastal or island forests. The majority (60%) of these forest raptors occur exclusively or partly in the tropics.
The rare Grey Falcon Falco hypoleacos is the only threatened raptor from inland Australia. Other taxa which do not occur in the tropics include the Australian subspecies of the rare Sooty Owl Ninox strenua. The endangered subspecies of the Southern Boobook Ninox novaeseelandiae undulata and the Wedge-tailed eagle Aquila audax fleayi occur on temperate Norfolk Island and Tasmania respectively. The extinct Southern Boobook N.n.albaria occurred on temperate Lord Howe Island.
The Red Goshawk, Erythrotriorchis radiiatus (vulnerable) is restricted to the forests and savannah woodlands of the tropical north, while the Square-tailed Kite, Lopoictinia isura (rare) is migratory and has a much wider distribution which accounts for the different status of the two species. Both raptors are from monotypic genera and have always been considered uncommon.
Destruction of forests and woodlands, particularly in eastern Australia, is now the main threat to both species. Illegal egg-collecting and shooting are the problems for a few pairs whose nest location has been advertised or those which breed to close to human settlement (Debus & Czechura 1989; Aumann & Baker-Gabb 1991). Pesticides are not inhibiting breeding success in remote locations, but they may be a problem in northeast Australia where cropping and the use of pesticides is widespread. Current fire and grazing regimes do not limit the density of prey and the availability of suitable nest trees, but their long term effects are unknown.
The red-tailed goshawk and Square-tailed Kite occur in several conservation reserves. Additional conservation measures required for both species include: surveys in northeast Australia to locate and protect nest sites outside reserves, not revealing the location of nest sites in order to protect pairs from egg collectors, and education of landowners with poultry near known pairs of raptors so that they are not illegally shot.
There are four subspecies of the Masked Owl Tyto novaehollandiae. The Tasmanian subspecies T.n. castanops is secure, the widespread mainland subspecies T.n. novaehollandiae is rare while T.n. kimberley from the north of mainland Australia and T.n. melvillensis from Melville and Bathurst Islands are insufficiently known (Garnett 1992).
All Masked Owl subspecies will use altered habitats and forest margins, particularly for foraging (Schodde & Mason 1980). However, they favour the forest interior for roosting and nest in large hollows in tall, old trees. Such trees can be destroyed by high intensity fires late in the dry season in the tropical north (Garnett 1992). Current Forestry Management practices may also limit nest site availability in some areas. Conservation measures proposed for threatened subspecies of the Masked owl include: studies of basic ecology, particularly home rang, diet and nest requirements and the effect of current fire, forestry and agricultural practices on nest site availability (Garnett 1992).
There are three subspecies of the Rufous owl, Ninox rufa. In northwest Australia N.r. rufa is secure, N.r. queenslandica of the northeast is rare and N.r. meesi of Cape York is insufficiently known (Garnet 19992). All subspecies of Rufous Owl occur at low densities (Schodde & Mason 1980). They roost and nest in rain forest, but often forage in nearby woodlands and wetlands.
Though many pairs of Rufous Owl occur in conservation reserves, some habitat outside reserves is being cleared for agriculture. Hot fires late in the dry season are the greatest threat because they burn the fringes of rain forest and can destroy nest trees (Garnett 1992). Weed invasion is also a problem in some Rufous Owl habitat. Conservation measures proposed include surveys to obtain a more accurate assessment of the abundance and the status of nest sites. Particular attention should be paid to the effects of habitat clearance, invasion of the habitat by weeds and the effects of current fire management practices (Garnett 1992).
: On Christmas Island the Brown Goshawk Accipiter fasciatus natalis and Indonesian Hawk-Owl Ninox squamipila natalis occur as vulnerable subspecies of widespread, secure species. There are about a hundred pairs of each subspecies (Stokes 1988; Olsen & Stokes 1989). Clearance of forest was the main threat, but this has ceased and much of the Island is now national park. Conservation measures proposed include collecting information on the effective population sizes, productivity and recruitment to confirm whether the small populations are viable in the long term.
Despite the fact that less than 30% of Australia is covered in forest, all but one of it's 15 threatened raptors is a forest dweller, and most (73%) are owls. While clearance of forests for agriculture was formerly a major threat, this is no longer the main threat for most taxa. In tropical Australia, the main threat now is the loss of large hollow-bearing trees and those which might eventually replace them due to inappropriate fire and forestry management practices. Studies need to be undertaken to provide alternative management strategies and to elucidate the biology of several taxa which are not well known. The most important area for this work to be undertaken is in northeast Australia.
Thanks to Stephen Garnet for providing information on threatened raptors prior to it's publication and Nick Mooney for presenting this paper Berlin Conference.
D.J. Baker-Gabb
abstract from Raptor Conservation Today
1994, WWGBP / Pica Press