A living ‘Rawnsley's Bowerbird’ - an adult male resulting from a wild hybridisation between a Regent Sericulus chrysocephalus and Satin Ptilonorhynchus violaceusBowerbird
DANIEL BLUNT 1 and CLIFFORD B. FRITH 2
1, 21 Gwingana Ct , Beechmont Queensland 4211
(Email: email@example.com )
2, ’Prionodura’, P.O. Box 581, Malanda, Queensland. 4885
‘Rawnsley’s Bowerbird’, originally and erroneously described as the species Ptilonorhynchus rawnsleyi (Diggles 1867) from an individual bird specimen in adult male plumage, is in fact the result of a wild intergeneric hybridisation between a Regent Sericulus chrysocephalus and a Satin Ptilonorhynchus violaceous Bowerbird. The unique skin specimen of this hybrid combination disappeared prior to 1950 and another example was not recorded until the presently reported sightings, here supported by digital (1 November 2003) and photographic (10 January 2004) image evidence, of a living adult individual at 28° 10.689S 153° 11.343E (elevation 661m) at Timbarra Drive, Beechmont, some two kilometres from Binna Burra, Queensland, located adjacent to Lamington National Park.
‘Rawnsley’s Bowerbird’ was originally described and illustrated as the new species Ptilonorhynchus rawnsleyi by a hand coloured plate in part 15 (issued in 1867) of the now extremely rare three volume (and unfinished) ‘The Ornithology of Australia’ by Silvester Diggles (1866-70). The unique adult specimen of Rawnsley’s Bowerbird, collected at Witton, near Brisbane, Queensland on the 14 th of July, 1867 by Henry Charles Rawnsley, has to date been regarded by various authors to have represented: (a) a valid bowerbird species P. rawnsleyi, (b) an adult hybrid individual resulting from the natural crossing of a Regent Bowerbird Sericulus chrysocephalus with a Satin Bowerbird Ptilonorhynchus violaceous or (c) an aberrant or ‘sport’ individual of the Satin Bowerbird.
A comprehensive review and consideration of all facts associated with this odd taxon Ptilonorhynchus rawnsleyi led to the conclusion that it must represent a wild hybrid between the Regent and the Satin Bowerbird (Frith and Frith 2004; C. Frith unpublished data). Both of these bowerbird species breed polygynously, their promiscuous males building bowers structures of the ‘avenue’ type that they decorate with various objects and to which they attract multiple females during each breeding season in order to there court and mate with them (Frith and Frith 2004).
The only specimen and known example of this intergeneric bowerbird hybridisation was in adult male plumage. It was predominantly of the all glossy blue-back appearance of an adult male Satin Bowerbird but differed from this in having a conspicuously extensive yellow wing patch, fine yellow tipping to some tail feathers, a paler and more dilute iris colour, and was of a size intermediate between that of an average-sized adult male Satin Bowerbird of the southern or nominate subspecies (P. v. violaceous) and a Regent Bowerbird (see Fig. 1a). The gonad condition of this individual bird was never mentioned and it is therefore possible that it may have been sterile. Unfortunately the unique specimen, never held as part of any institutional collection but last known to have be in the hands of the widow of Silvester Diggles (Marks 1965), mysteriously disappeared some time before Tom Iredale wrote his monograph about the bowerbirds and the birds of paradise (Iredale 1950).
Augustus C. Gregory (1819-1905), Surveyor-General of Queensland (Whittell 1954), upon being shown the specimen of Rawnsley’s Bowerbird by Charles Coxen (John Gould’s brother-in-law and his agent resident in Australia; Datta 1997) of Brisbane, claimed to have seen such a bird on the Suttor River, a branch of the Burdekin River, more than a decade previously. Gregory’s identification was, however, quite correctly seriously doubted at the time by his field companion Dr Elsey who “for some time very naturally imagined he Mr G. [Gregory] might have made some mistake.’ (Coxen in litt. to John Gould 20 October 1867). John Gould (1869) also doubted that Gregory saw such a bird. There is no doubt that Gregory’s memory failed him, and he possibly confused his sighting what was actually a Common Koel Eudynamys scolopacea at the location in question (which well out of the range and appropriate habitats for both Regent and Satin Bowerbirds; C. Frith unpublished data).
No second specimen or any sighting of any other individual bird apparently resulting from hybridisation between the Regent and Satin Bowerbirds has been collected or recorded respectively.
On 1 November 2003 DB noticed an odd looking bowerbird perched on a domestic fowl pen through the window of the house at 60 Timbarra Drive Beechmont. Intrigued as to what the bird was, DB pursued it to find it perched high in a New England Black-butt (Eucalyptus andrewsii). Using an Olympus C-750 Digital Camera and its 10X optical zoom several images were taken of the bird, with two subsequently proving of particular interest for identification (see Plate 1 and 2). Upon further investigation, DB learnt that Stuart Skeen (SS) had several garden bird feeders in the area of the bowerbird sighting and so he contacted him. SS responded by reporting having also noticed a bird fitting DB’s description, the bird apparently being a regular but intermittent visitor to the feeders. DB also made enquiries as to the identification of the bird and it was identified using Raftopuolos (1988). DB again visited the site several times in order to obtain better images of the bird but it did not reappear while he was there. SS was able to obtain a photographic image of the bird using a disposable compact camera, that being the last and the only other reasonable image of the bird obtained to our knowledge.
In the field DB recorded the bird as generally behaving more like a Satin Bowerbird than a Regent Bowerbird, but as it perched and couched on a branch it did exhibit behavioural movements like that of a Regent Bowerbird. SS also noted that the bird associated socially with Satin Bowerbirds and moved about amongst flocks of them. SS thinks that the bird might also have attended his bird feeding station in sub-adult plumage during 2002/3 (when it already had some of the yellow wing plumage). If this was so then the individual concerned was some seven years of age toward the end of 2003 given what is known of the attainment of adult male plumage in Satin and Regent Bowerbirds (cf. Frith and Frith 2004).
While all three images presented here of the living hybrid individual are of relatively poor quality due to difficult conditions prevailing at the time and limitations of the equipment used, they do provide adequate evidence in support of DB’s observations and of our interpretation of the bird’s origin. As the images herein show the living bird had the appearance, general proportions, and characteristics of an adult male Satin Bowerbird but differed from that taxon in that its wings had a conspicuously large area of bright yellow on their secondaries, it had an obviously paler (less blue and more aqua-green) iris, and a shorter and darker bill (see Plates 1 and 2).
We have no doubt that the adult plumaged individual bird depicted in the images herein represents a living example of the result of a wild hybridisation between a Regent and a Satin Bowerbird. This hybrid combination was previously erroneously described as the species Rawnsley’s Bowerbird Ptilonorhynchus rawnsleyi by Diggles (1867). As it is inappropriate that a wild hybrid bird be given a common name (and of course seriously erroneous it be given scientific one) the name Rawnsley’s Bowerbird can be used but informally.
Wherever breeding populations of these two bowerbird species occur sympatrically such a hybridisation must be considered a possible, if exceedingly rare, event. The two bowerbird genera involved (Sericulus, consisting of the Regent Bowerbird and three congeneric ‘silky’ bowerbird species of New Guinea, and Ptilonorhynchus consisting of only the Satin Bowerbird) are closely related and at least one authority has suggested they should be combined to form a single genus together with the other three Sericulus species (Storr 1973, 1984) but this has not been followed (Frith and Frith 2004 and references therein).
That congeneric bowerbird species of the genera Amblyornis, Sericulus and Chlamydera do hybridise in the wild has been confirmed (Frith and Frith 1995, 1998, 2004). A large number of intergeneric bird of paradise hybrid combinations, many also involving two polygynous species with dramatically differing adult male plumages (Frith and Beehler 1998), may be seen as supporting potential hybridisation between the polygynous and morphologically distinctive Regent and Satin Bowerbird as possible. It is, however, a remarkable fact that no such hybrid bowerbird has ever been so much as vaguely alluded to as having been seen by a single one of the hundreds of thousands of bird watchers annually visiting areas where these two bowerbirds commonly share breeding habitat (e.g. Lamington National Park) since 1867. Until, that is, the above dates of 2003.
We sincerely thank Stuart Skeen for kindly permitting DB to visit his property and for permission to reproduce his photographic image of the living hybrid bird. DB is grateful to Barry Davies for kindly making his copy of Raftopoulos (1988) available to him for initial identification of the bird. CF thanks Ann Datta, Librarian at The Natural History Museum, London, for kindly providing details of original John Gould correspondence held in that institution. Dawn Frith kindly commented on a draft of this note.
Datta, A. (1997). John Gould in Australia – Letters and Drawings. Miegunyah Press,
Diggles, S. (1867). The Ornithology of Australia: being illustrations of 244 Australian Birds, with descriptive letter-press. Part 15. The author, Brisbane.
Frith, C.B. and Beehler. B.M. (1998). The Birds of Paradise: Paradisaeidae . Oxford
University Press, Oxford.
Frith, C.B. and Frith, D.W. (1995). ‘Hybridization between the Great and Spotted
Bowerbird Chlamydera nuchalis and C. maculata, the first authenticated hybrid
bowerbird (Ptilonorhynchidae)’, Memoirs of the Queensland Museum 38, 471-476.
Frith, C.B. and Frith, D.W. (199 8). ‘Hybridization between Macgregor's Bowerbird
Amblyornis macgregoriae and the Streaked Bowerbird A. subalaris
(Ptilonorhynchidae) of New Guinea’, Bulletin of the British Ornithologists' Club
Frith, C.B. and Frith, D.W. (2003). The Bowerbirds: Ptilonorhynchidae. Oxford
University Press: Oxford.
Gould, J. (1869). Birds of Australia Supplement. The author, London.
Iredale, T. (1950). Birds of Paradise and Bowerbirds, Georgian House, Melbourne.
Marks, E.N. (1965). ‘Notes on Diggles “Ornithology of Australia”’, The Queensland
Raftopoulos, B. (Ed) (1988). Birds of Paradise ‘Golden Age Illustrations’ A Precursor Edition to the Facsimile Volume of Daniel G. Elliot’s – ‘A Monograph of the Birds of Paradise’. Oz Publishing Co. Brisbane .
Storr, G. M. (1973). ‘List of Queensland Birds’, Special Publication of theWestAustralianMuseum No. 5, 1-177.
Storr, G. M. (1984). ‘Revised List of Queensland Birds’, Records of theWestAustralianMuseum No. 19, 1-189.
Whittell, H.M. (1954). The Literature of Australian birds: a history and a bibliography of Australian ornithology, Paterson Brokensha, Perth.
Plate 1. A reproduction of the hand-coloured illustration of the unique ‘type’ of Ptilonorhynchus rawnsleyi painted and published by Diggles (1867). At top left. Photo by C.B. Frith
Plate 2. A digital image of a living adult male bird standing on the ground resulting from wild hybridisation between the Regent and Satin Bowerbirds, taken on 1 November 2003 at 28° 10.689S 153° 11.343E at some two kilometres north-west of Binna Burra, Queensland. Note yellow wing patch, pale iris and darkish bill colour. Image by and courtesy of Stuart Skein.
Plate 3. A photograph of a perched living adult male bird resulting from wild hybridisation between the Regent and Satin Bowerbirds, taken on 10 January 2004 at 28° 10.689S 153° 11.343E some two kilometres to the of Binna Burra, Queensland. Note yellow wing patch and darkish bill. Photo by D. Blunt.
Plate 4. A photograph of a perched living adult male bird resulting from wild hybridisation between the Regent and Satin Bowerbirds taken on 10 January 2004 at 28° 10.689S 153° 11.343E some two kilometres to the of Binna Burra, Queensland. Note yellow wing patch, pale iris and darkish bill. Photo by D. Blunt.