The history and present status of goats on the Auckland Islands (New Zealand subantarctic) in relation to vegetation changes induced by man

Abstract

ADSTllACfGoats were liberated in at least 10 places on the Auckland Islands in the late nineteenth century as food for castaways. Only one population now survives, comprising about 100 animals. They live on the north-west side of Port Ross which is one of the driest and warmest parts of tho main island.The vegetation on parts of tho island, but particularly where the goats now live. has been occasionally burnt and cleared. In summer 1972-73 the status of the goats and of their habitat was surveyed. A preliminary map was drawn of present vegetation around Port Ross. and permanent plots were established to follow continuing vegetational changes.At sea level the southern boundary of goat distribution was a shallow stream. They were constrained altitudinally by the distribution of suitable food sources, and by weather conditions in the upland. Virtually the whole day was spent fceding, and reproductive behaviour. play, or inactive rest were not seen. Ninety-two percent of groups contained five or fewer animals who moved around meeting other groups and parting again. Decause of the peat substrate, the goats had overgrown, split hooves and they ran poorly. Five goats caught by hand had body measurements that were. in general, above the means for a mainland population. Seventy-five percent were predominantly white or grey. Direct observation showed that open scrub and fine-grass swards were favoured above forest, tussock grassland, and dense scrub as feediPlg areas; a conclusion supported by the relative quantities of plant species in faecal pellets.Palatable plants were potentially most abundant in the Myrsine divor{cata community which formed the scrub line. This community was too dense and too wet to be used by goats however, and in practice the best of the accessible sources were: low-altitude open scrub, and fine-grass swards. Much of the forest interior was bare but this was due morc to site history than to browsing by goats. In canopy gaps, forest plants regenerated within thickets of unpalatables, so that they eventually reached the canopy. In the same way, sites modified by man have regenerated. and this will probably continue even in the presence of goats.The goats do not endanger plant communities or rare species within their present range, and arc not likely to spread. 221

Lateglacial and Holocene vegetation and climatic change on Auckland Island, Subantarctic New Zealand

“…Pigs (Sus scrofa) were introduced to the north end of Auckland island in ad 1807 one year after European discovery, and have depleted most of these palatable forbs from all but inaccessible sites. There has been no detailed survey of the vegetation of the islands aside from an early, generalized account (Cockayne, 1909), and a survey of the vegetation in the vicinity of Port Ross, northern Auckland Islands (Rudge and Campbell, 1977). The vegetation of the Auckland Islands has been mapped as five main formations: forest and scrub; upland tussock grassland; maritime grassland/herbfield; mountain tundra (fellfield); bogs and swamps (see C.D.…”

Patterns of endemic extinctions among island bird species

“…n/a n /a n /a Yap lslands 120 180 1200 3 0 0 n/a n /a n /a East Caroline Islands 580 790 2100 13 2 4 n/a n /a n /a Admiralty Islands 2000 720 275 6 0 2 n/a n /a n /a Islands 180 1380 640 3 0 2 n/a n /a n /a Ogasawara Islands 73 400 1000 4 3 1 n/a n /a n /a Nansei Shoto Islands 4500 1930 50 8 1 5 n/a n /a n /a Wake Island 7 6 3100 1 1 0 n/a n /a n /a Nauru 21 70 2200 1 0 1 n/a n /a n /a Rotuma 47 250 2700 1 0 1 n/a n /a n /a Niuafo'ou 55 250 3000 0 0 0 n/a n /a n /a Tonga 700 1030 3100 1 0 0 9 0 n/a Antipodes Islands 21 400 2400 1 0 1 n/a n /a n /a Rapa 40 630 5500 1 0 1 n/a n /a n /a Pitcaim 5 340 5600 1 0 1 n/a n /a n /a Nihoa 1 280 4500 0 0 0 n/a n /a n /a Easter Island 162 510 3700 0 0 0 5 0 n/a Niue 259 70 3800 0 0 0 2 0 n/a Guadalupe Island 280 1300 250 2 1 1 n/a n /a n /a Socorro Island 150 1130 450 4 1 2 n/a n /a n /a Cocos Island 47 700 500 3 0 3 n/a n /a n /a Brobkorb (1972), Olson (1978Olson ( , 1985, Milberg Milberg andTyrberg (1993) 7000 andTyrberg (1993) Lesser Antilles Brobkorb (1964), Olson (1978), Steadman et al (1984), Watters et 5000 Milberg andTyrberg (1993) al. (1984), Pregill et al (1988Pregill et al ( , 1994, Steadman (1999b), Reis and Steadman (1999), Steadman and Hilgartner (1999 Worthy and Holdaway (1995), Holdaway (1999) 1200 Rouse (1986) South Island New Zealand Millener (1991, Worthy and Holdaway (1995), Holdaway (1999) 1200 Rouse (1986) Auckland Islands 200 Rudge and Campbell (1977), Chernow and Vallasi (1993) Chatham Islands Tennyson and Millener (1994), Millener (1999) 500 Irwin (1992) Southern Cook Islands Steadm...…”

Change in the distribution of the indigenous grass Poa litorosa on sub-Antarctic Macquarie Island following the eradication of rabbits

“…The three previously known southern populations were first detected following the postmyxomatosis decline in rabbit numbers in the early 1980s when grazing pressure was reduced (Terauds et al 2014). Indeed, P. litorosa has been found to decline in the presence of grazing and increase when grazing ceased on several of the New Zealand shelf islands (Dilks & Wilson 1979, Rudge & Campbell 1977, Taylor 1968, UNESCO 1966. When grazed, P. litorosa and F. contracta are difficult to tell apart, thus these populations may have been established for some time but were not detected previously due to grazing impacts (Bergstrom et al 2006).…”