A survey of burrow-nesting petrels on Macquarie I. between 1975 and 1982 confirmed breeding of the white-headed petrel Pterodroma lessoni, blue petrel Halobaena caerulea, Antarctic prion Pachyptila desolata, fairy prion Pachyptila turtur, sooty sheanvater Pufinus griseus and common diving petrel Pelecanoides urinatriw. A further six species were recorded. The population size of all burrow-nesting petrels has been adversely modified by alien fauna introduced last century. Of the six species breeding, one is stable, two are diminishing and three are present in very low numbers. Current deterioration of their status is localized and with proper management there may be recovery, particularly of the three last species.

Pest species management is causing rapid and signifi cant changes to burrow-nesting petrel populations on sub-Antarctic Macquarie Island. The Weka, Gallirallus australis, was eliminated by 1989 and the Feral Cat, Felis catus, eradicated in 2000. The most abundant burrow nesting petrel species currently, White-headed Petrels, Pterodroma lessonii, Antarctic Prions, Pachypti!.a desolata, and Sooty Shearwaters, Puffinus griseus, have yet to increase in numbers, but are expected to do so in the absence of cats. This study found evidence that Grey Petrels, Procellaria cinerea, began breeding again on the island in 1999, after an absence of over 100 years. Blue Petrels, Halobaena caerulea, and Fairy Prions, Pachyptila turtur, were found to be re-colonising Macquarie Island from offshore stacks after a similar absence. South Georgian Diving-Petrels, Pelecanoides georgicus, were also possibly recolonising the island. Despite the presence of Black Rats, Rattus rattus, most of the bird species discussed are considered capable of population increase. If European Rabbits, Oryctolagus cuniculus, are not elimi nated or maintained in reduced numbers, some petrel populations will never fully recover. Climate change could have a negative impact on burrow-nesting petrels, and is likely to exacerbate the detrimental effects of the remaining pest species on vulnerable indigenous bird species, compounding the need for remedial action against rabbits in particular. Together with predictions that other petrel species will now return to breed, certain terrestrial bird species, alien to the region, may invade Macquarie Island as a consequence of the combination of pest eradication and changing climatic conditions.

Nineteen colonies of the king shag, Phalacrocorax albiventer purpurascens, occur on Macquarie I. varying in size from 3 to 320 breeding pairs. The total population was estimated at 660 breeding pairs in 1975-79. Breeding varied annually, but most eggs were laid in the last half of October with an average clutch size over two seasons of 2.7 eggs. Most chicks hatched by late December and fledged from late January onwards. Minimum age at first breeding was 2 years but most shags did not breed until the age of 4 years or more. Faithful breeding pairs tended to be more successful than those that changed mates although most remained together for only one or two seasons. Male shags had a stronger tendency to retain their nest-site than did females, and it was the female that was responsible for the breakdown of the pair-bond. This breakdown and annual variation in breeding success was thought to be mainly due to shortage of food, which consisted solely of benthic fish.

Myxomatosis was successfully introduced into the rabbit population on Macquarie Island, Australia, in November 1978 as a biological control agent. Up to February 1981, success had not been achieved over the whole island, primarily because of the irregular distribution of Spilopsyllus cuniculi (Dale) (the introduction of which had begun in 1968) and the occurrence of rabbits in isolated and sedentary pockets. Continuing the introduction of the virus and vector should extend the control and permit the recovery of important subantarctic plant alliances.

A fi rst comprehensive survey of seabirds at Bishop and Clerk islets conducted on 23 December 1993 recorded a total of 12 species. Dur ing a three-hour-long visit by helicopter, nine species were found breeding, mostly in nests on the ground, bur also in burrows dug in shallow soil. These included the largest known colony of Black-browed Albatross, Thalassarche melanophris, in Australia. Ten bird species are now known to breed at the islets. Species accounts are given including data on morphometrics, abundance, habitats, breeding, threats, interspecifi c competition for space and unpublished information.

Surveys were carried out between 1987 and 1989 on Maatsuyker I. and nearby Needle Rocks off southern Tasmania to establish the status and identification of the seals present. New Zealand fur seals, Arctocephalus forsteri, were found on Maatsuyker I. There were at least 15 pups born on the island in 1987/88. Australian fur seals, Arctocephalus pusillus doriferus, use the islands as a haulout site but do not breed here. The distribution of New Zealand fur seals can now be amended to include Tasmanian waters. Records discussed here also alter aspects of the status of Australian fur seals because the Maatsuyker group is not a breeding site for this species and breeding colonies are therefore restricted to Bass Strait waters.

Since December 1968, 241 600 rabbit fleas (Spilopsyllus cuniculi (Dale)) have been released on Macquarie Island (between Australia and Antarctica) as a vector of myxomatosis for the biological control of rabbits. The flea is now established but is unevenly distributed due to its low rate of reproduction and slow rate of spread, especially into small isolated pockets of rabbits. The number of rabbits infested was greatest following the rabbit breeding season. Levels of infestation on individual rabbits were low; of 5135 rabbits shot in 3 years, only 21 carried more than 100 rabbit fleas. Limits to the spread and survival of the fleas on the island are discussed.

No abstract