VOL. 11 (2) JUNE 1985 35 AUSTRALlAN BIRD WATCHER 1985. II. 35-45 A Rockhopper x Royal Penguin Hybrid from Macquarie Island By KN.G. SIMPSON, Science Department, Victoria College - Burwood Campus, Burwood, Victoria 3125* Summary A specimen of Eudyptes penguin (Spheniscidae: Aves) originally collected in 1957 from North Head, Macquarie Island, after being identified as a Snares Penguin Eudyptes robustus Oliver 1953, has been re-identified as a hybrid between the Rockhopper Penguin E. chrysocome filholi Hutton 1878 and the Royal Penguin E. chrysolophus schlege/i Finsch 1876. Some facial identification features are discussed. Introduction AEudyptes penguin skin in the collections of the Museum of Victoria (MV) has a somewhat chequered history of identification and is festooned with labels and amendment tags. B7313, an adult female, was originally M/57 /B/111 collected by M. P. Hines under the auspices of Australian National Antarctic Research Expeditions (ANARE) on 3 November 1957, in the North Head Rockhopper/Royal Penguin colony, Macquarie Island. It was identified in the field as a Snares Penguin Eudyptes robustus. Another penguin of generally similar appearance, MY B7312, was also collected during 1957. B7313 certainly (possibly B7312 as well), was submitted to the late Dr (Sir) R. A Falla in New Zealand for confirmation of identification, and published by Keith & Hines (1958). B7312, collected on 17 March 1957 after completing its moult, does meet all of the identifiable characters of E. robustus and I accept it as such. One earlier record of Snares Penguin at Macquarie Island was on 5 February 1950 [Gwynn (1953) - see his plate facing p. 150] and that bird too, I accept as being E. robustus, a Snares Penguin. Keith & Hines (1958) noted that B7313 'was found in a mixed colony of Royal Penguins and Rockhopper Penguins Eudyptes chrysocome (Forster) but was not mated'. They also noted 'ovary was in full breeding condition'. The skin, taken in November, is in excellent plumage and shows no sign of moult. Initial label data were as follows: Label I. 'Michael Hines' Antarctic Collection, 1956-57.' Label 2. ANARE label - 'Macquarie Island, North Head, 3/ 11 /'57, (Face) M. P. Hines, M/57 /B/1 11 '. Note in pencil added by A. R. McEvey: 'E. robustus by Falla'. (Reverse) 'Bill uniformly brown Feet pinkish, black soles Iris red, tending to brown T.L. to tail 670 (mm) to toes 685 (mm) Flipper span 483 mm Weight 7 lb 2 oz·. *Formerly Antarctic Division, Department of Supply, Melbourne AUSTRALIAN 36 SIMPSON BIRD WATCHER Discussion The North Head colony is one of several on Macquarie Island where some small number of Royal Penguin nests meet and are interspersed among nests of Rockhopper Penguins. Most of the Royal and Rockhopper Penguin colonies on the island are discrete from each other. The breeding season of the two species is largely concurrent; sympatry thus occurs in some limited areas (Figure 1). 1 2 3 1. North Head 2. Aurora Point 4 3. Double Point 4. Rockhopper Point 5 5. Cape Star 6 6. Caroline Point Figure 1. Six localities on Macquarie Island where Royal Penguin and Rockhopper Penguin colonies are very close together or where they actually merge. Other such contacts may occur but were not recorded during my period on the island, December 1963- March 1964; December 1964- March 1966. These six sites are likely localities for hybrids to be found. Hybrid B7313 came from North Head. Drawing by Nicolas Day VOL. 11 (2) JUNE 1985 Rockhopper x Royal Penguin Hybrid, Macquarie Is. 37 Male Erect-crested Penguin 'paired' with female Royal Penguin, Flat Creek, Macquarie Island, 14-31 January 1964. Note wide space about the pair. Plate 6 ANARE photograph: KN.G. Simpson The opportunity for potential hybridisation is fairly obvious when so many Royal and Rockhopper colonies are so closely positioned or overlapping. Occasionally, Macquarie Island is visited by other Eudyptes species, e.g. the Snares Penguin mentioned in the paper so far (Gwynn 1953), and also by a steady trickle of Erect-crested Penguins E. sclateri. The potential of these for 'pairing' at least temporarily, although it was the moulting seasonjollowing the local breeding season, was demonstrated by a male Erect-crested which 'paired' with a female Royal Penguin during the moult. This was at Flat Creek, to the north of Aurora Point, between 14 and 31 January 1964 (Plate 6). The two penguins aggressively defended an area two or three times larger than is normally utilised by moulting Royal Penguins. During 1970 B7313 was identified as a Rockhopper by Simpson and A R. McEvey, based initially on superciliary stripe-crest (SSC) texture and on the position of the anterior tip of the SSC. An amendment tag was added: 'On point of origin of crest, and crest texture, colour and composition, I consider it to be E. chrysocome - (signed) A R. McEvey, 22/9/70'. AUSTRALIAN 38 SIMPSON BIRD WATCHER In 1972 I again examined the specimen and noted that across the black of the anterior crown and frons, but not visible at the feather surface, were many short parti-coloured black and yellow feathers. The laterally positioned and exposed SSe is chrome-yellow, much richer in colour than that of the normal adult E. c.filholi, and rather approaching the golden-yellow (sometimes almost reddish golden) frontal crest of the adult E. c. schlegeli. Snares Penguins have yellow SSes also, but perhaps not so richly coloured as in this particular specimen. The spread of yellow-black feathers across the frons and anterior crown is a diagnostic character of the Macaroni E. chrysolophus chrysolophus/ Royal E. c. schlegeli complex and (so far as is known) is not exhibited in other extant Eudyptes penguins. I have named it the 'frontal crest'. Available specimens of Eudyptes in the MV collections were examined for the presence of small yellowish/black frontal plumes. They were found only where they should be, on Macaroni and Royal Penguins. None were found on any Rockhopper from any source nor on the specimens of Snares Penguins, Fiordland Penguins E. pachyrhynchus, or Erect-crested Penguins E. atratus available to me. In B7313 the anterior tip of the SSe is perhaps 2-3 mm broader than is normal for Rockhopper Penguins. In this it again superficially resembles the Snares Penguin. The nature or texture of the SSe is definitely fibrous. I have identified this feature as an absolute character of the Macaroni/Royal complex, and of all Rockhoppers. In this character B7313 shows its correct affinity. The other Eudyptes species - Snares (including the specimen B7312), Fiordland and Erect-crested- all have their own absolute character, silky textured SSes. This character of the sse, fibrous versus silky, is fundamental in separating the two natural groups of Eudyptes penguins. In B7313 the anterior tip of the SSe is positioned precisely on (at) the middle (bisection) of the g/c baseline*, another absolute character of the Rockhopper Penguin complex. The anterior tip of the SSe in the Snares Penguin (as exemplified by B7312) is always positioned forward of the g/c baseline bisection. In the skin of B7313, perhaps in life too, the SSe is depressed closely against the sides of the head, quite unlike the protruding, 'untidy' posterior portion of the SSe of the average Rockhopper Penguin. This may well have been a principal reason for it being picked out of the North Head colony for collection. But, in yet two more head characters, the 'illusion' of a Snares Penguin is created and maintained. The lores of this bird B73 13 are reflective (glossy). This is a Snares feature but is also frequently a Macaroni/Royal feature and is therefore not so surprising. In Macaroni/Royals, the lores are very variable (see Plate 12) and not all of the paler-lored birds have reflective lores. *The g/c baseline is a line drawn precisely from the angle of the gape (g) to the proximal base of the exposed culmen (c). It is of great value in separating the species of Eudyptes with lateral sse and is my own 'invention.' VOL. II (2) JUNE 1985 Rockhopper x Royal Penguin Hybrid, Macquarie Is. 39 Comparison of four Eudyptes penguin skins from Macquarie Island: Top Royal Penguin 82478. A fairly typical specimen. Note massive bill, pale face (variable from black to white in the entire population), black upper !ores (may be entirely or partly black). A fibrous frontal crest arises on frons, spreads across head and back over the eyes. The colour is a rich gold, almost 'red-gold' in some birds. See also Plate 12 of live Royal Penguins. Second Top The hybrid Rockhopper x Royal Penguin 87313. Note smaller bill, dull black face but 'glossy' or 'reflective' black !ores. Particularly note the position of the fibrous SSC at its most anterior point, and compare it with the Rockhopper (below). Second Bottom Rockhopper Penguin 811865. Note bill only slightly less in size to hybrid penguin; dull (non-reflective) black face and I ores. Particularly note the position of the fibrous sse at its most anterior point- it terminates at precisely the same point as does that of the hybrid penguin. Now compare this with the Snares Penguin at bottom. Bottom Snares Penguin 87312. Note medium-sized bill, glossy black face and !ores. Particularly note position of the anterior point of the silky SSC - it arisesfor~va rd of the position where both hybrid and Rockhopper Penguin's SSC arises. This is the pa.rticular Snares Penguin taken in the same year as the hybrid bird. Plate 7 Photograph of Museum of Victoria ski ns: KN.G. Simpson AUSTRALIAN 40 SIMPSON BIRD WATCHER Details of the hybrid Rockhopper X Royal Penguin B7313 (upper) and of the Rockhopper Penguin 811865 (lower).