AUSTRALIAN 160 BIRD WATCHER

More Australian Breeding Records of the White-fronted Tern

By J. S. WHINRAY, Flinders , 7255.

In January 1979 some White-fronted Terns Sterna striata Gmelin were found breeding in Tasmania on in the . This New Zealand species was not known to have bred in previously (Whinray 1980, 1981). White-fronted Terns bred on Battery Island in late 1979 and in late 1980. Eggs had been laid there by late October 1981 but, although the rookery had been abandoned by early in December, more eggs were laid later that month. The records for those three seasons are detailed below, and several comments are made on them. Finally some comments are made on the local White-fronted Tern breeding records, distribution, numbers, and clutch size. Battery Island Records 15 December 1979 On this visit I agam found Silver Gulls Larus novaehollandiae, Fairy Terns Sterna nereis, and White-fronted Terns breeding by the summit of the south-eastern point. Except for one nest, the three species again used separate but adjacent nesting areas. The exception was a White-fronted Tern nest separated from the others by the Fairy Tern nests. The gullery started at the southern and south­ eastern edges of the White-fronted Tern rookery. The latter rookery was larger than in January 1979 and included not only the area used then by the species but also a little of the area used at that time by the Silver Gulls. Thirteen of the fourteen White-fronted Tern nests were shallow depressions in the succulent mat. Three nests had two eggs each and four nests had one egg each. Three nests had two chicks each and three nests had one chick each. The exception was a small shallow depression on the gently sloping granite face around which most of the other White-fronted Tern nests were sited. There was nothing in that nest but the single egg and it was being incubated. All of the chicks were small and none could be banded as their shanks were too thick for bands of the specified size to close around them. The chicks have to be running freely, or be very close to that stage, before their shanks have lengthened and thinned enough to take the bands. Eighteen adults, all of which had full breeding plumage, were at the rookery when I reached it. Adults came and went during the visit; some of the arrivals carried sardine-sized fishes. 29 December 1979 The largest number of adult White-fronted Terns recorded during this visit was eleven and there was no change in their plumage. VOL. 9 (5) MARCH 1982 More Australian Breeding Records of White-fronted Tern 161

Four large chicks, almost large enough to fly, were found by the rookery and banded. Some adults attacked in the usual way as this was being done. Few of the nests seen during the previous visit could be distinguished. The White-fronted Tern that was still incubating had an egg, and its nest was a shallow depression in the succulent mat at the north-eastern part of the rookery. However, as the nests found during the earlier visit were not marked, it was impossible to tell if this were a new nest. Only four more chicks were found. The smallest was still in a nest and another was beside it. The other two were near the south-eastern nest and one of them was just large enough to be banded. No dead chicks were seen at the rookery nor were there any flying immature birds. There could have been considerable mortality since the prior visit. 6 December 1980 White-fronted Terns, Silver Gulls and Fairy Terns were breeding again by the summit of the south-eastern point. All the White-fronted Terns had full breeding plumage and the largest number seen was fourteen. The White-fronted Terns had twelve nests in the usual area, none being separate this year. Three nests had two eggs each, and one nest had two chicks. Three nests had one egg each, three nests had one chick each (one of which had just hatched), and one nest had a hatching egg. The twelfth nest was empty but an adult sat on it each time I left the rookery; perhaps it intended to lay there. In addition there was one chick away from all the nests. Two of the chicks were large enough to be banded but, as that was not anticipated, the bands had not been taken. 25 December 1980 The adult White-fronted Terns still had full breeding plumage, and the largest number counted at the rookery was thirteen. Two of the chicks were able to fly and could not be banded. Eight were banded and only one of those was by a nest. There was one egg in that nest but it Jacked any mark. Although eggs were marked during the last visit, only one might have been done in each nest. However the size of the chick suggested that the nest was one of those recorded during the prior visit. The eggless nest, noted during the prior visit, was still empty and had been abandoned. One nest had a partly hatched chick dead in an egg that had been marked during the same visit. Both it and a hatched egg were collected and given to the Tasmanian Museum (registration number B 3703) . 23 October 1981 Both White-fronted Terns and Fairy Terns had started to Jay by the summit of the south-eastern point. T he former had two nests in the usual area and a third four metres south-east of it, in what had been the gullery in the previous three seasons. The latter nest had two eggs; the others had one egg each. All three nests were marked with numbered metal tags. There was only one Fairy Tern nest. The highest number of White-fronted Terns seen near the rookery was twelve and all were in full breeding plumage. AUSTRALIAN 162 WHINRAY BIRD WATCHER

1 December 1981 As I neared the islet, it was obvious that there were no terns of any sort at the south-eastern point, nor were any White-fronted Terns seen during the visit. The remains of fourteen Silver Gull eggs were collected hurriedly in their usual rookery but fragments encroached into the usual White­ fronted Tern area by about a metre. All of these eggs appeared to have been broken and eaten when fresh. Small holes, made from the outside, were found in four shells and they seemed the right size-up to 7 mm by 4 mm- to have been made by Silver Gulls. The rock near the broken eggs was cream and white with a heavy coating of bird droppings and that suggested the presence, for some weeks, of a number of birds. 22 December 1981 I steamed near the islet to check it on my way to the far south-east of the Group and was surprised to notice White­ fronted Terns rising from the south-eastern point. The highest number recorded there was ten, and all were adults in full breeding plumage. Two nests had two eggs each, and two other prepared nests were discernible. Three of these were in the usual area but the other, with eggs, was at the same spot as the isolated nest found on 23 October. The birds usually stay on their nests until one approaches to within about twenty metres, and then return as soon as one moves about that distance away from the rookery. By contrast, on this occasion they left their nests as I landed about seventy metres away and returned to them only after I left the islet. As there was enough time, more pieces of Silver Gull egg shells were collected, and one of them also had a small hole made from the outside. They came from ten eggs, making a total of twenty-four eggs abandoned at the south-eastern point gullery. Of course there could have been more. The 1981 Battery Island Abandonment Falla, Sibson & Turbott (1966) saw the White-fronted Tern's breeding habits as 'Notoriously capricious; a site successfully used one year may not be used the next; or else a few pairs will return, lay a few eggs in a rather desultory way and then abandon the site for the rest of the season'. Soper (1972) gave a less qualified account. He noted that the 'birds have a habit of capriciously changing their breeding sites from one year to the next and even of suddenly deserting a breeding site, for no apparent reason, after eggs have been laid and incubation begun'. Perhaps his account is derived from Falla et al. (1966). By contrast, Oliver (1955) failed to mention abandonment after laying had begun, and made only the general comments that 'Terns do not always continue to nest in the same locality. After a few years in one spot they will change their nesting site. Sometimes they will breed in the same place on alternate years.' With so small a White-fronted Tern population at Battery Island, three nests are a significant proportion of the number of possible nests and so the early abandonment in 1981 seems different from that mentioned by Falla et al. (1966). VOL. 9 (5) MARCH 1982 More Australian Breeding Records of White-fronted Tern 163

When writing of the Silver Gull, Serventy, Serventy & Warham (1971) noted that 'Predation on the eggs and young of other birds is probably mostly a consequence of human interference in sea-bird rookeries'. As all the Silver Gull eggs which I found on the south-eastern point of Battery Island appeared to have been eaten, possibly by the same species, human interference might have been responsible for the abandonment of that gullery by early December 1981. It might also have caused the abandonment by that date of the point's terneries. Australian Breeding Records White-fronted Terns have now bred at Battery Island for three seasons (1978-1979 to 1980-1981) and laid there twice during the 1981- 1982 season. They laid eggs on in 1979 (Jones 1980) and bred on ;Reef in late 1979 and late 1980 (Davis & Mykytowycz 1982) . In addition they bred on Fisher Island Reef and on the northern Billy Goat Reef in late 1981 (Napier 1982) . All these records suggest that the White-fronted Tern is now established as a permanent breeding species in the Furneaux Group. It might have bred here several years before those records were made as I found a pair in full breeding plumage on the north-western point of Mile Island on 24 December 1976. Their continued attacking of myself, and then the other members of the party, was noted at the time. A hasty search during the visit revealed no chicks but it was partly a tussock-grass area and difficult to cover adequately. A more thorough search would have been made had I known then that their behaviour was typical of the species when it is tending young. By the next visit, on 4 January 1977, the adults were gone. This record was overlooked when my first paper ( 1980) was written. With three known local rookeries, the Australian breeding population should be better protected against natural disaster or human interference than if there were but a single larger rookery. Furneaux Group Distribution and Numbers Because the late 1981 White-fronted Tern breeding sites were up to 26 km apart, it may seem likely that the species could have bred at intermediate sites. However I checked a number of Furneaux Group islets and reefs during the period October to December 1981 without finding any breeding birds except at the three places mentioned above. The other areas checked then were Rabbit Island and Rabbit Reef (both off Settlement Point, ), , Mile Island, Little , Reef, North-East Chappell Reef, Little , Isabella Reef and the un-named reef south-west of it, Mid , both Black Reefs, , , Rocky Head Reef, Seal Reef (off Seal Point, Clarkes Island), the un­ named reef north-west of , and the (south-east of Clarkes Island). Some of those areas were checked up to five times during the period but, despite all the travelling, no White-fronted Terns were seen at sea. Second year (sub-adult) birds were found on rocks just south-east of (passed on 23 October) and on the un-named reef south-west of Isabella Reef (19 November) . AUSTRALIAN 164 WHINRAY BIRD WATCHER

While there were about a dozen unchecked reefs and islets in Franklin Sound, it was impossible for me to reach them during the period October to December 1981 without abandoning my continuing survey of the western, south-western and southern islets and reefs of the Group. The White-fronted Terns recorded in the Furneaux Group during that period were: Breedin{? birds Sub-adults Battery Island (Oct.) 12 Near Preservation Island (Oct.) 6 N. Billy Goat Reef (Nov.) 14 Near Isabella Reef (Nov.) 9 Fisher Island Reef (Nov.) 2 Total 28 Total 15 Napier (1982) is the so urce for the Billy Goat and Fisher Island Reef numbers. The numbers give n for the breeding sites are the highest noted at each place. These figures, and the lack of other sightings, suggest that although the local population is fairly widespread, it is probably not large yet. It should now include two-year-old and three-year-old birds which were raised on Battery Island and there could be, as well, at least one two­ year-old bird which was raised on Fisher Island Reef. It seems unlikely that any of those birds would travel to New Zealand to breed. Australian Clutch Size The Furneaux Group sample, drawn from all four nesting sites, is twenty-three clutches of two eggs or chicks, and nineteen clutches of one egg or chick. In reaching that total a nest with one egg was omitted for the 1980-81 season at Battery Island in case the loose chick came from it. While this Furneaux Group sample is small, the numbers favour slightly the clutch of two. By contrast Falla et al. (1966) state that the New Zealand White-fronted Tern clutch is 'commonly 1, sometimes 2'. Acknowledgements All the trips mentioned in this note were made possible by the very generous loan of Mr G. W. G. Goode's boat. Mr J. R. Napier kindly allowed me to draw on his 1981 records, and Mr I. J. Skira kindly sent me a copy of the Davis & Mykytowycz draft. References Davis, G. & Mykytowycz, M. (1982), 'Further Breeding Records of White-fronted Terns in Tasmania', Australian Bird Watcher vol. 9, 158-159. Falla, R . A. , Sibson, R . B. & Turbott, E . G. (1966), A Field Guide to the Birds of New Zealand . . . , Collins, London. Jones, W. G. (1980) , Tasmanian Bird Report no. 9, 34. Bird Observers' Association of Tasmania, Hobart. Napier, J. R. (1982), Note on the Breeding of the White-fronted Tern in Franklin Sound, Flinders Island, Australian Bird Watcher (in press). Oliver, W. R . B. (1955) , New Zealand Birds, A. H. & A. W. Reed, Wellington. Serventy, D. L., Serventy, V. & Warham, J. (1971) , The Handbook of Australian Sea-Birds, A. H. & A. W. Reed, Sydney. Soper, M. F. (1972) , New Zealand Birds, Whitcombe & Tombs, Christchurch. Whinray, J. S. (1980) , 'The First Australian Breeding Record of the White-fronted Tern', Australian Bird Watcher vol. 8, 137-146. --- (1981), 'A Discredited Early Australian Breeding Record of the White­ fronted Tern', Australian Bird Watcher vol. 9, 41-43. ABW