264 



G. R. WILLIAMS 



Most unusually, Little Barrier is now free of 

 any grazing or browsing mammals, and has 

 only the Polynesian rat (a reminder of the 

 Maori occupation) and feral cats (a European 

 legacy) to impair its extreme importance as a 

 reserve. The rats have been unmolested by 

 man because, rightly or wrongly, they are con- 

 sidered ineffective predators generally; how- 

 ever, their impact has probably been under- 

 rated. More than half a century of trapping 

 and hunting of cats by successive caretakers 

 on the island has not effectively reduced that 

 population. 



Among its other important attributes, 

 Little Barrier supports two birds endemic to 

 New Zealand the rare black petrel (Procel- 

 laria parkinsoni), and one endemic honey- 

 eater, the stitchbird (Notiomystis cincta), 

 which was once widespread on the North Is- 

 land but is now found only on Little Barrier in 

 moderate numbers, and apparently in no im- 

 mediate danger. The impact of feral cats on 

 stitchbirds has not been determined, but it is 

 known that cats are seriously affecting the 

 black petrel especially: they kill at least 90% 

 of the chicks and some adults annually. Their 

 impact on a locally remnant population of 

 Cook's petrels (P. cookii) is apparently less 

 severe. 



In 1968-69 the Wildlife Service, with veteri- 

 nary advice and assistance, added an attempt 

 at biological control to the campaign of poi- 

 soning ("1080" in fish was the poison and bait 

 used), trapping, and shooting. The very 

 specific viral disease feline enteritis was in- 

 troduced by trapping island cats, infecting 

 them, and then releasing them. Some esti- 

 mates of the resulting mortality from the 

 combined techniques were as high as 90%; but 

 there has been a recovery since, and the cam- 

 paign is expensive in both time and man- 

 power. And, oddly enough, the control effort 

 has met with some opposition. Nevertheless, 

 another campaign is planned. 



Habitat Rehabilitation by 

 Destruction of Mammals 



The Kermadecs are a group of small islands 

 about 800 km north-northeast of the North 

 Island. Their biological significance, insofar 

 as this symposium is concerned, is that they 

 are the southernmost breeding area in New 

 Zealand seas for many elements of the Pacific 



tropic and sub-tropical marine avifauna. Un- 

 fortunately, goats were liberated on the two 

 largest islands Raoul (3,000 ha) and 

 Macauley (300 ha) almost 150 years ago and 

 Macauley Island was burnt over; such forest 

 cover as it had was severely damaged or de- 

 stroyed, probably at about the same time. The 

 goats were to be an emergency food supply for 

 whalers and shipwrecked mariners. Cats, too, 

 became feral on Raoul Island during one of its 

 fitful periods of occupation. The New Zealand 

 Wildlife Service, in spite of the distance and 

 difficulties involved, has undertaken pest de- 

 struction campaigns on both islands, but I 

 offer here only an account of the simpler, and 

 more successful, Macauley operation. 



In 1966, a 5-week expedition to this water- 

 less and almost treeless island resulted in the 

 shooting of what was then thought to be all of 

 its 3,000-odd goats (a density of about 15/ha). 

 Four years later, a follow-up expedition found 

 and destroyed another 17 goats (a later brief 

 inspection suggested that these were indeed 

 the last), and rehabilitation of the island is 

 well under way. Now that the short turf is dis- 

 appearing, erosion of the soft volcanic soils is 

 reduced. With compaction no longer occur- 

 ring, it will be interesting to see what the ef- 

 fect will be on birds breeding on the island- 

 six breeding species of petrels, three breeding 

 species of terns, and other marine species. 



Sociolegal Conservation 



The taking of petrels and other procellarii- 

 form birds for food has always been part of 

 the Polynesian economy and culture through- 

 out the Pacific. In New Zealand, the practice 

 now has only minor economic importance, but 

 it is still an essential part of Maori culture and 

 tradition. The most commonly taken species 

 are the sooty shearwater (Puffinus griseus) 

 and, until recently, the gray-faced petrel 

 (Pterodroma macroptera). Although no formal 

 study of the impact of the annual harvest of 

 chicks on the population has yet been made, 

 all the indications are that it is not signifi- 

 cant. Nevertheless, the Maoris willingly ac- 

 cepted the limited amount of legislation that 

 has been passed to afford the two principal ex- 

 ploited species at least token protection. How- 

 ever, on the Chatham Islands, where there is a 

 strong tradition of taking some of the alba- 

 trosses, this tradition has persisted, even 



