VOL. 8 (3) SEPTEMBER, 1979 Ornithological Studies at Casey 69 Ornithological Studies at Casey, Antarctica, 1977-1978 By ALAN N. COWAN, 6A Vancouver Street, Red Hill, A.C.T., 2603. Summary This paper reports on ornithological work carried out by the author during his stay at Casey, Antarctica, as Medical Officer to the J 977 wintering party from February 1977 to February 1978. Preliminary notes on the history, geography and climate of Casey and on previous local studies are followed by an outline of the programme undertaken and of the problems encountered. The annual cycle of birds and other animals is briefly described. Systematic accounts are then given of each bird species, with status in the area including numbers where estimates have been attempted, and notes on behaviour. Introduction Casey, the most recently built of Australia's Stations on the Antarctic continent, lies on the Budd Coast just above the Antarctic Circle at 66° l7'S. Lat., 110° 32'E. Long. The station is on the Bailey Peninsula at the N.E. end of Vincennes Bay, which was named by Mawson after the Vincennes, a vessel of the U.S. Exploring Expedition of 1838 to 1842 (Commander, Lt. Charles Wilkes, U.S.N.), the first explorers in the area. Wilkes Station, just N. of Casey, was built by the U.S. Navy in 1957 for the International Geophysical Year. Subsequently taken over by Australia in 1959, it was abandoned in 1969 when Casey was completed and occupied. Geography Several glaciers flow into Vincennes Bay, whose coastline is mainly one of steep slopes of permanent ice and snow broken here and there by moraines and nunataks. In the N.E. part of the bay is the complex chain of the Windmill Islands, the main scenic feature of the a rea and also the mai n focus of ornithological interest. In summer, many of these rocky islands become extensively denuded of snow, providing nesting sites for the Antarctic seabirds which throng the area for the brief breeding season. They are the only available exposed rock area of any size in at least 800 km. of coastline. Two of these islands, Ardery and Odbert constitute a Specially Protected Area under the Antarctic Treaty 1967. They support breeding populations of the Antarctic P etrel (Fig. 1) . Climate Considerably to the N. of such places as McMurdo Sound, Casey's climate is relatively mild. The mean daily maximum temperature for January is + 1 deg. C. and the mean daily minimum for July is -20 deg. C. (The Antarctic Pilot 1974, data for Wilkes). The wind is characteristi­ cally N.E. to S.E.. Blizzards may occur, often with little warning, at any season but are of highest velocity and greatest frequency and duration during the winter months. Katabatic winds are much less a feature of the Casey climate than they are at some other stations, and there are many calm days. During the summer months daylight is prolonged and the radiant energy of the sun is great, so that even on subzero days there is tremendous melting of snow and ice due to the heating of the dark rock beneath; rushing streams with profuse growth of algae are a feature of summer on these islands. AUSTRALIAN 70 COWAN BIRD WATCHER The sea ice in this region is notoriously unstable, and except for certain protected channels and bays can break up quite suddenly under the influence of tide and wind. Previous Ornithological Work in the Area Since the U.S. withdrawal the Wilkes-Casey area has been rather neglected in respect of bird studies and Australian biological work in Antarctica has been concentrated elswhere. The reasons are obvious; unless boats are available for visiting the bird breeding islands through the summer, observations terminate when the sea ice breaks up in spring. The last extensive use of (U.S.) boats was by Orton in 1961 (Orton, 1963). Two trips were made by Hicks in 1963, and since then there has been no summer programme on the islands, except for brief helicopter visits dur· ing the few hurried days of changeover. In winter one can travel to most of the isl ands over the sea ice, but the birds are then absent, and even in winter the vicissitudes of the weather and its effects on th e sea ice can suddenly bring about a dangerous situation. It is very largely due to the keen amateur interest of previous Australian wintering expeditioners that there is a body of information on the zoology of the area. Most of this is unpublished (AN ARE Station Logs). The 1977 Biological Programme T he author chose Casey for his year's stay just because there was so much scope for research. It was clear that boats were essential and accordingly a biological programme using boats was written to be con­ ducted there during the year. The Director, Antarctic Division, approved the programme and authorised the purchase of two French-made Hutchin­ son "Mapa 401 " inflatable boats with Volvo "200" outboard motors. It may be difficult for the reader without Antarctic experience to appreciate the practical problems involved in such a programme. The prevailing wi nd is off the land. T he water is always very cold and one could not survive prolonged immersion. Travellers must be prepared to camp for several clays on an island if overtaken by the weather. Tent, food, radio etc. must be carried. The two boats must never separate. Waters are largely uncharted and shallow reefs abound. Pack ice is always a menace and may appear capri­ ciously and unexpectedly, forcing extensive detours by small inflatable boats. A precise calendar of the complex seasonal movements of some bird species is hard to obtain. Dates vary with latitude and from year to year depending on, among other factors, snow accumulation at nest sites and the occurrence of blizzards. Observations are limited by weather condi­ tions and by restrictions on travel imposed by essential work at the station. Even a brief study period on the islands requires a major logistic exercise involving at least 3 men, 2 boats and much equipment being absent for a cl ay. Observations were therefore far from continuous. However we made 15 trips in the inflatables during December 1977 and January 1978. We had in fact attempted our first trip in March 1977 but this proved abortive due to early autumn sea ice formation. In addition a final trip was made in the ship's boat during changeover in January 1978. Most of the trips were to Ardery and Odbert, but the Roll-O'Connor group and Peterson VOL. 8 (3) SEPTEMBER, 1979 Ornithological Studies at Casey 71 = CHARLTON!. <\::::) DEWART I. NELLY l.:c::;::. - FRAilER IS. 1(,1;;.15'5 ~~~~~- <;,G " \ 5 '5 I SHIRLEY \. I RIDGE. ARDE.RY ;V ODB~ HOLL \ \?c?))JS:D Qo I PENNEY BAY 0 ' eooew" KILOME.TRE.S4 " '~ Figure 1. The Windmill Islands. For clarity, only those places mentioned in the text are labelled. AUSTRALIAN 72 COWAN BIRD WATCHER were also visited. Earlier in the season, of course, visits to many of the islands were made on foot across the sea ice. The boats were forced to make a long detour across the open sea out­ side Hollin and Midgley and their associated reefs until late December when the Robertson Channel became clear; this allowed us a shorter and more sheltered route. However, O'Brien Bay remained frozen during the whole summer and we always had to sail outside Beall, while the channel inside Shirley opened just in time for our very last trip in the inflatables. It was stipulated that the boats were only to be used for the one year, at the end of which they were to be brought back to Australia. In fact they suffered damage and, though repaired, could not have been regarded as seaworthy for a second season. The Annual Cycle It will perhaps be helpful to describe the general pattern of the breeding cycles of the Antarctic animals and of the observations recorded throughout a typical Antarctic year. With the exception of the Emperor Penguin, a winter breeder which visits the Casey area after the breeding season, all the birds are summer breeders. Most begin to arrive in October although the Southern Giant­ Petrel is earlier and Wilson's Storm-petrel later. In general the breeding cycles of the "fulmarine petrels" are highly sychronous. Throughout this paper the term "fulmarine petrel" is used to include the tour specJes Southern Fulmar, Antarctic Petrel, Cape Petrel and Snow Petrel, but to exclude the Giant-Petrels. The last•- named should properly be included in the expression, but I have adopted this course for the sake of brevity. On the other hand the cycles of the Southern Giant-Petrel and Wilson's Storm-petrel are much less synchronous. The later and less synchronous breeding cycle of Wilson's Storm-petrel is lucidly discussed by Beck (1970) and seems to be well adapted to the bird's burrow-nesting habits; it is often late in the season before the burrows can be cleared of snow by this weak digger of delicate build. A severe blizzard at a critical time could destroy the young of an entire area if all were at the same stage of being newly hatched and having built up no fat stores. Most of the species depend heavily on zooplankton which is super­ abundant during the summer and early autumn. Fledging and departure must be completed before the winter. Most species leave the colonies by late March but the Southern Giant-Petrel, Wilson's Storm-petrel and South Polar Skua stay later, until April or May.