198 AUSTRALIAN

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AUSTRALIAN BIRD WATCHER 1997, 17, 198-202

More on Early Records of the 'Cave Owl' of the Nullarbor Plain

by IAN A.W. McALLAN, 46 Yeramba Street, Turramurra, N.S.W. 2074

Masked Owls Tyto no,.vaehollandiae are rarely reported alive from the Nullarbor Plain, the last published records dating from the early 1980s (Debus 1993). Such records are so rare that some authors have contended that the species may have become extinct in the area (Schodde & Mason 1980, Burbidge et al. 1987, McAllan & Bruce 1989), though this status may be unwarranted (Debus 1993). On the Nullarbor early this century there was much confusion between this species and the sympatric Barn Owl T. alba (Parker 1977). An examination of an early Masked Owl record, recently published, reveals several errors concerning its origin as well as further details of the species from the same area.

Debus (1993) discussed an early photographic print of a Masked Owl from the Nullarbor Plain. The bird was thought to have been photographed by K.A. Hindwood in a cave on the Nullarbor during the 1930s. This belief was on the basis that the photograph was found with a collection of Hindwood's photographs, which had been in the possession of one of Hindwood's associates. Notes on the reverse of the print indicate that the bird was 'The Cave Owl of the Nullarbor Plain' , and also mention the 'Trans Australian Railway' . There were notes for printing and cropping of several photographs in the collection, including the Masked Owl photograph. Although the record had been overlooked in most ornithological literature until Debus's paper, it had been published previously.

The photograph was apparently first published in 1931 (Barrett 1931), under the heading 'The Camera in Wild Nature's Realm[.] Photographs by the Author'. Clearly, the photograph was not taken by Hindwood. The photograph subsequently appeared in several other publications (Barrett n.d. 1 [ = 1932], n.d. 2 [?=early 1930s], 1935, 1943). I have also found an undated post-card, typical of the 1930s, published for 'The Trans-Australian Railway' which features the same photograph.

The photograph was probably taken by Barrett on a trip to the Nullarbor Plain in May 1930 (Barrett 1930, overlooked by Whittell 1954 and Kloot 1995). In this account, residents of the area were said to refer to the owls found in the nearby blowholes and caves as 'Cave Owls'. Initially, Barrett considered that these records all referred to Barn Owls; a photograph of a juvenile Barn Owl was included in his paper (identity confirmed by S. Debus in litt.) . Barrett also saw three 'Cave Owls' in captivity at Madura Downs homestead in the Western Australian section of the Nullarbor Plain.

Barrett's identification of the Tyto owls of the Nullarbor had not changed the following year, when the photograph of the Masked Owl was first published (Barrett 1931). He noted:

The 'mysterious' Cave Owl of the Nullarbor Plain is really a pale-colored variety of the Delicate or Barn Owl, a familiar species .. . These birds of silent flight prey upon small lizards, marsupials, and rodents . They nest in the blow-holes and caves, often many feet from the surface of the plain.

However, by 1932 Barrett realised that the owl he had photographed was not a Barn Owl, for he noted (Barrett n.d. 1):

The cave owl of the Nullarbor Plain, which nests in blow-holes and caves, has long been regarded as merely a smaller, pale-colored geographical variety of the masked owl (Tyto novae-hollandiae). Lately it has been accepted as distinct enough to receive a scientific title of its own- Nullarborensis. It closely resembles the familiar barn owl, and preys upon house-building rats , bandicoots, etc.

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Both the Barn Owl (left) and the Masked Owl (right) are found in caves of the Nullarbor Plain, and are likely to have been confused as 'Cave Owl'.

Plate 21 Drawing: Will Rolland

This account, accompanying the photograph of the Masked Owl, was sufficient to describe the taxon Tyto nullarborensis. It is important to date this publication more accurately, especially when it is realised that it contends with the name Tyto novaehollandiae troughtoni, first published in 1931 (Cayley 1931 ; cf. McAllan & Bruce 1989). The Museum of Victoria has a copy of Barrett's publication date-stamped '29 NOV 1932'. It is likely that this is close to the publication date of this booklet, as the Museum was a repository for ornithological publications. The type specimen of Tyto nullarborensis is the bird pictured, which appears to have been alive at the time; as such it probably was not preserved and is no longer in existence. Barrett's apparent change of opinion, that the species is more closely related to the Masked Owl than to the Bam Owl, may merely reflect the taxonomy in use at the time, as suggested for some other early records (Parker 1977).

By about 1935, Barrett's opinion of the 'Cave Owl' had reversed: he once again considered it to be a Bam Owl (Barrett n.d. 2, also overlooked by Whitten 1954 and Kloot 1995). The photograph of the Masked Owl again referred to the birds as Bam Owls. This identification was repeated in subsequent publications (Barrett 1935, 1943). The latter book did not include the Masked Owl photograph, as used in the

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other accounts, but another photograph that is undoubtedly of a Masked Owl (S. Debus in litt.), albeit out of focus.

It is unclear whether Barrett's photographs all involved captive birds. Barrett apparently visited the Nullarbor Plain only once. He mentioned seeing only 'young' captive birds at Madura Downs homestead. He may have also photographed some birds in one of the nearby cave systems, given that he had photographs of adult Masked Owls (those of 1931 and 1944). He visited 'Merguda Cave, on the lowlands' in which he found 'a cave owl's nest' (Barrett 1935), 'Dingo Donga Cave, about twenty miles from the Overland Track, where one goes down through a gorge to Madura Downs homestead' (Barrett 1930, 1935), and 'Lynch's Cave, within coo-ee, almost, of Loongana station' where he also noted that 'a pair of owls nested' (Barrett (1944). The latter two localities are in Western Australia, and the first (which I have not located), given the restriction to 'lowlands', is almost certainly from that state as well. The photograph published in Debus (1993) is only the second confirmed record of the Masked Owl from the Western Australian section of the Nullarbor Plain, the other being a skeleton collected near Cocklebiddy in 1962 ( cf. Mees 1963, Storr 1987).

Other Tyto owls were also photographed on the Nullarbor at about the same time. A.G. Bolam worked along the Trans-Australian Railway between 1915 and 1942; from 1918 until 1925 he was posted at Ooldea on the eastern edge of the Nullarbor Plain (Crawford 1979, Kloot 1995). He published a photograph of a Tyto owl taken in the area (Bolam 1923). Its specific identity is difficult to determine, as its feet are not pictured and its wings are viewed largely from the underside. It appears to be an adult Barn Owl: it has a Barn Owl 'jizz', thin rim to its facial disc and lacks the dark eye 'shadows' of the Masked Owl (also S. Debus in litt.).

Although Whitlock (1922) was the first to publish the term Cave Owl for Tyto owls on the Nullarbor, the name was probably already in widespread use. Bolam's (1923) account of the birds is as follows:

As its name implies, the Cave Owl makes its home in the caves and blowholes of the Nullarbor Plain. The ledges that project from the side walls of the blowholes form favorite nesting places for these curious birds. The Cave Owl is a big bird, with snow-white feathers, but its face is ringed all round with light brown feathers, and there is a sprinkling of brown on its wings. There is a wonderful expression conveyed by its large eyes and brown eyebrows. The Cave Owl appears only at night, and in the moonlight it presents a beautiful sight as it perches on the limestone rock or some small scrub on the edge of the Plain. This species of the owl tribe is probably confined to the Nullarbor.

A later edition of the book (Bolam 1924) showed the same photograph, but the text was modified to add:

There is a wonderful expression conveyed by its large eyes and brown eyebrows. I shall never forget the expression of anguish in the eyes of a dying Owl which had been shot; it was really wonderful. . . The Owls used to be seen almost every night, but as they caused havoc among the chickens the shot guns had to be used upon them and they are now rarae aves.

The fourth edition of the book (Bolam 1925) used a different photograph of two young owls. Again, the feet were out of view, but dark 'shadows' around the eyes, heavy rims to the facial discs, and strongly spotted crowns suggest that the birds were Masked Owls.

As previously noted, I have an undated post-card with Barrett's first Masked Owl pictured, and titled on the reverse 'The Trans-Australian Railway'. It has the caption:

The Cave Owl. A big bird, usually snow-white, which inhabits the blowholes of the Nullarbor Plain. The large eyes and brown eyebrows give this bird a remarkable facial expression. Appears only at night, and lives on the small marsupials and birds of the Plain. Very partial to chickens.

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These notes suggest that Barrett supplied the photograph to the Commonwealth Railways who added an abridged version of Bolam's writings. Barrett himself acknowledged Bolam as a 'friend' (Barrett 1935).

These two authors give a little additional information concerning the prey of the owls of the Nullarbor. Assuming that chickens are too large for Bam Owls to kill easily, Bolam gives further evidence that Masked Owls will take chickens (see Debus 1993 for another record). The 'Cave Owl' was said to be a major predator of the Greater Stick-nest Rat Leporillus conditor which was still found on the Nullarbor Plain in numbers during the 1930s (Barrett 1935). It cannot be determined which species these 'Cave Owls' were. Eckert (1971) reported the collection of a Bam Owl (from West Franklin Island) whose stomach contained the remains of a Greater Stick­nest Rat; 80% of the contents of pellets collected at the same roost contained the remains of this species, and a further 10% contained Southern Brown Bandicoot /soodon obesulus. The owl specimen concerned is in the South Australian Museum [=SAM], B27694; it has been confirmed as a Bam Owl with unusually pale tail and wing feathers (pers. obs.). There were many partly eaten rats on the island, with the hindquarters usually left uneaten. It was assumed by Eckert that the Barn Owl was the main predator of the rats. The pellet contents suggest that, if necessary, Bam Owls can survive on prey as large as the Rat (180-450 g) and the Bandicoot (400-1600 g, Strahan 1995). On this basis the two owl species may have had a large degree of overlap in their preferred prey on the Nullarbor, the presence of remains of a prey animal in a pellet not necessarily meaning that all of the prey had been consumed.

Debus (1993) considered Le Souefs (192la) record of Masked Owl valid (cf. Parker 1977). Le Souefs record was of two 'Chestnut-faced Owls' which he later reiterated were large and dark with no sign of white on them (Le Souef 192lb). Although Parker (1977) suggested that this was a record of the Masked Owl, in his fmal assessment he dismissed all non-specimen records. This approach may have been too harsh. Indeed, if the presence of Bam Owls needed to be proved by specimens, Parker had even fewer specimens of this species at his disposal. There were only the two clutches mentioned by him as well as a single skin, SAM B30514, collected on 1 October 1975 from near Cook, S.A. (M. Penck pers. comm.). There are apparently no specimens of Bam Owls from the Null arbor Plain in any other Australian museum.

Subsequently, a further four Tyto specimens have come from the Nullarbor Plain and are lodged in the South Australian Museum (P. Horton & M. Penck pers. comm.); there are no further Tyto specimens from this area lodged in the Western Australian Museum (R. Johnstone pers. comm.). The SAM specimens were all collected at Ivy Cave on Koonalda Station, S.A. , in 1984 (see Burbidge et al . 1987). The first specimen, B39434, is the skeleton of a juvenile bird that is not fully ossified and is midway between adult Bam and Masked Owls in size. Presumably, this bird is an immature Masked Owl. Specimen B38527 is a clutch of two long-abandoned eggs that are too large to be Bam Owl (47.6 X 38 mm; 48.2 X 36.6 mm); again these are probably from Masked Owls (see photograph in Burbidge et al. 1987). Specimens B38528 and B38529 are both skeletal remains that can be attributed to Bam Owls (P. Horton pers. comm.) .

This recent evidence suggests that both species of owl were widespread on the Nullarbor Plain and the European inhabitants of the area confused them. It is possible that the two species exhibited some degree of niche overlap in this area, and on this basis it may be incorrect to assume that all the remains of 'medium-sized' mammals collected from old owl pellets on the Nullarbor are fr~o1p. M!isl<:ed Owls.

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Acknowledgements

I thank Philippa Horton and Maya Penck (South Australian Museum), Ron Johnstone (Western Australian Museum), Walter Boles (Australian Museum) and Rory O'Brien (Museum of Victoria) for access to information on specimens in their care. The Mitchell Library, State Library of New South Wales, proved its worth by having most editions of A.G. Bolam's book. Stephen Debus 's persistent promptings and helpful examination of old photographs have made me finish this short note which has languished too long. Much help was also received from an anonymous referee.

References Barrett, C . (1930), 'Wild nature on the Nullarbor Plain', Aust. Mus. Mag. 4, 115-121. -- (1931), The Weekly Times Wild Nature Book, Herald & Weekly Times, Melbourne. -- (n.d. 1 [ = 1932]), Australian Birds & Butterflies, Sun Nature Book no. 3, Sun-News Pictorial,

Melbourne. -- (n.d. 2 [?=early 1930s]), Australian Birds in Color No. 1, Colorgravure Publications (Herald

& Weekly Times), Melbourne. -- (1935), 'Wild nature on the Nullarbor', Walkabout 1(6), 11-15. -- (1943), An Australian Animal Book, Oxford University Press, Melbourne. -- (1944), Australian Caves, Cliffs, and Waterfalls, Georgian House, Melbourne. Bolam, A. G. (1923), The Trans-Australian Wonderland, 1st edn, McCubbin-James Press, Melbourne. -- (1924), The Trans-Australian Wonderland, 3rd edn, Modern Printing Co., Melbourne. -- (1925), The Trans-Australian Wonderland, 4th edn, Modern Printing Co ., Melbourne. Burbidge, A.A., Casperson, K.D. & Fuller, P.J. (1987), 'Birds', in McKenzie, N.L. &

Robinson, A.C. (Eds), A Biological Survey of the Nul/arbor Plain Region, South and Western Australia in 1984, 153-178, S.A. Dept Environment & Planning/W.A. Dept Conservation & Land Management/Aust. Nat! Parks & Wildl. Serv., Adelaide.

Cayley, N.W. (1931), What Bird is That? A Guide to the Birds of Australia, Angus & Robertson, Sydney .

Crawford, I.M. (1979), Introduction (pp. [v]-[vii]) to Bolam, A.G. (1927), The Trans-Australian Wonderland, facsimile 6th edn [Modern Printing Co., Melbourne], University of Western Australia Press, Perth.

Debus, S.J.S. (1993), 'The mainland Masked Owl Tyto novaehollandiae: a review', Aust. Bird Watcher 15, 168-191.

Eckert, H.J. (1971), 'Birds of the Franklin Islands and Eyre Island, South Australia', Emu 11, 61-64. Kloot, T. (1995), Whittell (1618-1950) Supplemented: Additions and Emendations to H.M. Whittell's

The Literature of Australian Birds, Bird Obs. Club Aust. Repon 6. Le Solief, A.S. (192la), 'Notes on birds seen on the Porongorup Mountains (near Albany), Geraldton,

and Ooldea (Transcontinental Line)', Emu 20, 140-144. -- (192lb), 'Observations at Ooldea', S. Aust. Ornithol. 6, 60-61. McAIIan, I.A.W. & Bruce, M.D. (1989), The Birds of New South Wales, A Working List, Biocon

Research/ N.S.W. Bird Atlassers Inc., Sydney. Mees, G.F. (1963), 'Status and distribution of some species of owls in Western Australia', West.

Aust. Nat. 8, 166-169. Parker, S.A. (1977), 'The distribution and occurrence in South Australia of owls of the genus Tyto',

S. Aust. Ornithol. 21, 207-215. Schodde, R. & Mason, I.J. (1980) [ = 1981], Nocturnal Birds of Australia, Lansdowne, Melbourne. Storr, G.M. (1987), 'Birds of the Eucla Division of Western Australia', Rec. West. Aust. Mus. Suppl.

27. Strahan, R. (Ed.) (1995), The Mammals of Australia, Australian Museum/Reed, Sydney. Whitlock, F .L. (1922), 'Notes from the Nullarbor Plain', Emu 21, 170-187. Whittell, H.M. (1954) , The Literature of Australian Birds: A History and Bibliography of Australian

Ornithology, Paterson Brokensha, Perth.

Received 3 July 1997 •