Vol. 6 MARCH 15, 1976 No.5

The Birds of Hogan Island, Bass Strait By S. R. MORTON* and R. W. BRAITHWAITE# INTRODUCTION The Hogan Group of islands (39° 13' S, 146°59' E) lies in Bass Strait between the Kent Group and Wilson's Promontory. Of the five main islands, Hogan Island is the largest at 133 hectares. Pre­ vious lists of the birds of Hogan Island indicated that only about ten species were present (Mattingley, 1938; Hope et al., 1974). We visited the Island from April 18 to 23, 1975, and observed an avifauna more diverse than that found previously. This report sum­ marises our observations. Six plant communities occur on Hogan Island (Scarlett et al., 1974), but the most extensive community is tussock grassland, and areas of shrubland are small. Although the vegetation has been burnt and cattle are grazed on the Island, Scarlett et al. ( 1974) con­ cluded that shrubland was never the dominant vegetation. Little Penguin, Eudyptula minor. Breeds on the Island; both adults and juveniles were present. Short-tailed Shearwater, Puffinus tenuirostris. Breeds on the Island; only juveniles were present. Black-faced Cormorant, Phalacrocorax fuscescens. Common around the shores of the Island. Little Grebe, Podiceps novaehollandiae. One seen resting in an inlet during daylight hours; it had gone the following morning. White Egret, Egretta alba. Two individuals seen on two successive days. White-faced Heron, Ardea novaehollandiae. At least 20 individuals seen every day. Black Swan, Cygnus atratus. Eight seen flying north towards the mainland from the direction of the Kent Group. Cape Barren Goose, Cereopsis novaehollandiae. Mr. P. A. Rawlinson, who· accompanied us to Hogan Island, counted 28 individuals during one day; he estimated that four to six pairs were resident. White-breasted Sea Eagle, Haliaeetus leucogaster. Two adults and one juvenile were observed. Peregrine Falcon, Falco peregrinus. One seen on one occasion.

* Department of Zoology, University of Melbourne, Parkville, Victoria- 3052 # Department of Zoology, Monash University, Clayton, Victoria- 3168 Bird 140 MORTON and BRAITHWAITE [ Watcher

Nankeen Kestrel, Falco cenchroides. One seen on several occasions. Brown Falcon, Falco berigora, At least four individuals present. One was found feeding on the corpse of a Short-tailed Shearwater, and pellets tentatively attri­ buted to this species contained fur of the Swamp Rat, Rattus lut­ reolus. Brown Quail, Synoicus ypsilophorus. Very common; aggregations of at least 20 individuals were dis­ turbed several times. Land Rail, Rallus philippensis. One seen in low shrubland. Sooty Oystercatcher, Haematopus fuliginosus. One pair present. Pacific Gull, Larus pacificus. Both this and the previous species were common, but we found no evidence of breeding by either on the Island. Silver Gull, Larus novaehollandiae. Fantailed Cuckoo, Cacomantis pyrrhophanus. A sub-adult individual seen in low shrubland. Boobook Owl, Ninox novaeseelandiae. One disturbed from dense tussocks in a shallow gully; no pellets were present. Pipit, Anthus novaeseelandiae. Very common. Blackbird, Turdus merula. Common. Golden Cisticola, Cisticola exilis. Several seen among low shrubland of Melaleuca ericifolia. Brown Scrubwren, Sericornis frontalis. One seen among dense tussocks in a shallow gully. It was observ­ ed closely for several minutes, had no visible brow-mark, and appeared dark brown in colour. Flame Robin, Petroica phoenici':!. Numbers appeared to fluctuate during our visit, suggesting that some movements to and from the Island were occurring. The greatest number seen was about 12, there being equal numbers of males and females. Grey Fantail, Rhipidura fuliginosa. At least 20 individuals were seen; the numbers appeared to fluctuate as in the Flame Robin. Eastern Silvereye, Zosterops lateralis. At least 50 individuals were present. Goldfinch, Carduelis carduelis. Nearly as common as the Eastern Silvereye. Wood-Swallow, Artamus sp. Large groups were observed but could not be identified speci­ fically. Their dark appearance indicated that they may have been cyanopterus. March ] Birds of Hogan Island 141 1976

Raven, Corvus sp. One pair was present; their slow deep calls suggested that they were probably tasmamcus. DISCUSSION Comparison of the above list of birds of Hogan Island with those provided by Mattingley (19 3 8) and Hope et al. (1974) indicate that the avifauna is more diverse than previously thought. Mattingley ( 1938) recorded only six species - Stubble Quail, Coturnix pectoralis, Sooty Oystercatcher, Silver Gull, Pacific Gull, Pipit and Blackbird. Hope et al. (1974) reported all these plus four further species - Little Penguin, Prion (probably Pachyptila turtur), Short-tailed Shearwater and Cape Barren Goose. We observed all these species expect Stubble Quail and Prion, and compiled a list totalling 29 species. Hence at least 30 species of birds can be found on Hogan Island; of this number, only seven are sea-birds. Two of the most interesting records for Hogan Island are the Golden Cisticola and the Brown Scrubwren. The only other island in Bass Strait from which the Golden Cisticola has been reported is King Island (Abbott, 1973). In view of its supposed sedentary habits, it seems likely that it is also a breeding resident on Hogan Island. If this is so, then the species is capable of existing in very small areas of suitable habitat, and may yet be found on islands of the Furneaux Group and in north-eastern Tasmania (see Sharland, 1972). The Brown Scrubwren is known from the Kent Group (Whinray, 1971), and a recent report suggests that the species may occur on Wilson's Promontory (Cooper, 1975). Our observations, although not supported by specimens, indicate that this species does extend further north than previously thought. It is worth noting that the taxonomic status of the species is uncertain, and Schodde ( 197 5) considers it to be con specific with the White-browed Scrubwren, Sernicornis frontalis. At first sight the number of species of birds found on Hogan Island is surprisingly high. Whinray ( 1971) reported approximately forty species from the Kent Group, even though Deal Island supports areas of Eucalyptus nitida and is ten times the size of Hogan Island. However Abbott (1974) found only sixteen species on Curtis Island, which is slightly larger than Hogan Island and carries areas of dense Melaleuca armillaris. There are two possible reasons for these differences. First, Hogan Island has several per­ manent freshwater soaks; and· secondly, the period of our survey coincided with the season of migration across Bass Strait. It is likely that most of the species were not resident on the Island, but were en route from Tasmania to the mainland. One special feature of the islands of eastern Bass Strait is their inter­ visibility and their regular spacing along a migratory route. If Hogan Island is the intermediate step between the Kent Group and the mainland, then a relatively small difference between the numbers of species utilising these two groups of islands may be Bird 142 MORTON and BRAITHWAITE, Birds of Hogan Is. [ Watcher

expected. Further, if the difference between the numbers of species of birds recorded from Curtis Island and Hogan Island is not merely a reflection of the time of survey in relation to the _period of migra­ tion, then it is possible that Hogan Island provides a more con­ venient stopping place for migratory birds. REFERENCES Abbott, I., 1973. "Birds of Bass Strait". Proc. Roy. Soc. Viet., 85: 197-223. Abbott, I., 1974. "Natural history of Curtis Island, Bass Strait. 5. Birds, with notes on mammal trapping". Pap. Proc. Roy. Soc. Tas., 107: 171-174. Cooper, R. P., 1975. "The avifauna of Wilson's Promontory. Part 6B. Passerines". Australian Bird Watcher, 6: 87-102. Hope, G., Brown, G., and Mcintosh, B.S., 1974. "Natural history of the Hogan Group. I. Physical environment and vertebrate fauna". Pap. Proc. Roy. Soc. Tas. , 107: 65-72. Mattingley, A. H. E., 1938. "Birds of the Hogans and other islands of Bass Strait". Emu, 38: 7-11. Scarlett, N. H., Hope, G. S., and Calder, D. M., 1974. "Natural history of the Hogan Group. 3. Floristics and plant communities". Pap. Proc. Roy. Soc. Tas., 107: 83-98. Schodde, R., 1975. "Interim List of Australian Songbirds. Pas­ serines". Melbourne: RAOU. Sharland, M., 1972. "Tasmanian Tailor Bird puzzle". Bird Observer, No. 484: 4. Whinray, J., 1971. "A list of birds of the major Kent's Group islands". Tasmanian Nat., 24: 2-3.

EDITORIAL NOTE Readers of The Australian Bird Watcher will regret to learn that its Hon. Editor, Roy P. Cooper, has had to undergo a very serious operation and will, for some time, be unable to perform Editorial duties. In his absence Jack Hyett of 39 Alwyn St., Mitcham, 3132, Victoria will be acting editor and editorial correspondence should be sent to him at the above address.