Influence of man on vegetation and wildlife of enderby and Rose Islands, Auckland Islands

Abstract

Two small adjacent sub-antarctic islands having many features in common, but with markedly different modified vegetation, are considered in the light of historical records and field work in 1954 and 1966. When the Auckland Islands were discovered in 1806 Enderby and Rose Islands probably had the same general vegetative pattern with southern rata (Metrosideros umbellata) forest and scrub on southeastern parts giving way to Poa Iitorosa tussock on the more exposed northwestern parts. MUl.h of the present vegetation on the two islands has been induced by fire and introduced mammals, the legacy of a period of shipwrecks and attempts at settlement and farming. Large areas of short sward and of dead trees now occur. Tussock grassland has practically disappeared from Enderby, but still covers much of Rose Island. Nowadays, mice (Mus mllscll/lls) , rabbits (Oryctolagus cllniclIllls), and feral cattle (Bos taurus) occur in Enderby, and rabbits alone on Rose Island. Their numbers, distribution, and interrelations with the vegetation are discussed. On Rose Island, where tussock and scrub are increasing, rabbits have markedly declined since 1954, whereas on Enderby an apparent balance has been reached between the introduced mammals and the much modified vegetation. The history and present status of bird and seal populations are described. After early exploitation and virtual extermination, southern royal albatrosses (Diomedea e. epomophora) and seals (Arctocephalus forsteri and Neophoca hooker;) are now increasing. On Enderby there are breeding sea-lions, many native bird species, cattle, and rabbits all in an interacting relationship which is not obviously detrimental to any of them or to the present vegetation. The Auckland Islands have been reserves for the preservation of flora and fauna since 1934 and are potentially valuable for studying interactions between native and introduced species. Existing environmental trends on Enderby and Rose Islands have positive conservation and scientific values and any manipUlation. such as the control of cattle and rabbits, now seems undesirable.

Quaternary sediments and plant microfossils from Enderby Island, Auckland Islands

“…1) has been well described by Taylor ( 1971 ) . The land surface is covered by a blanket of peat so that rocks are exposed only in coastal cliffs, which rise over 30 m to the northwest but are less than half this height to the east and south.…”

“…It certainly included grassland and sedges, herb meadow with Umbelliferae, Bulbinella, Colobanthus, Gentiana, Tillaea and scrub with Dracophyllum, Myrsine, Coprosma and Cassinia which perhaps sheltered Phymatodes and Lycopodium. Even today, plants normally classed as shrubs, such as Myrsine divaricata and Cassinia vauvilliersii, are dwarfed in exposed situations to form components of a moorland community (Taylor 1971) so the vegetation was probably a mosaic of grassland, sedge, herb meadow, and stunted scrub.…”

Neonatal Mortality in New Zealand Sea Lions (Phocarctos Hookeri ) at Sandy Bay, Enderby Island, Auckland Islands From 1998 to 2005

“…data). This is one of the smallest population sizes reported for an otariid species, and available data suggest that this population is declining despite having been protected since the late 1890s (Taylor, 1971;Wilkinson et al, 2003). Ninety percent of all breeding is concentrated on Dundas and Enderby Islands within the Auckland Islands group.…”

Historical and modern distribution and abundance of the New Zealand sea lionPhocarctos hookeri

“…Many are anecdotal, but they do provide a picture of the exploitation of sea lions from this area. Taylor (1971) provides a good summary of the history of sealing in the Auckland Islands.…”

“…In a visit in the summer of 1970/ 71, a maximum of 47 animals were counted consisting of 36 males and 11 females (Crawley & Cameron 1972). Crawley & Cameron (1972) also reported the presence of two pups that were probably born on the islands in 1969and 1971, respectively. Cawthorn (1993 estimated pup production for The Snares islands at 10 for the 1992/93 season.…”