Changes in the landsnail fauna of Lady Alice Island, northeastern New Zealand

Brook, F. J.

doi:10.1080/03014223.1999.9517588

Cited by 32 publications

(27 citation statements)

References 11 publications

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“…On the North Island, the seed and snail-shell evidence indicated the sudden onset of damage that began about 750 years ago. On Lady Alice Island, the disappearance of Amborhytida snails and the appearance of deposits of rat-gnawed Placostylus snails in sand dunes were interpreted through radio-carbon dating to indicate an invasion about 200 years ago (Brook 1999). The only rat species present when seed damage was first recorded for the North Island, and snail damage began on Lady Alice Island, was the Pacific rat.…”

Section: Circumstantial Evidence Of Rat Effects In New Zealandmentioning

confidence: 99%

Have the Harmful Effects of Introduced Rats on Islands been Exaggerated?

2006

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Introduced rats are now being eradicated from many islands. Increasingly, these eradications are contested by activists claiming moral, legal, cultural, historic or scientific reasons and poorly documented evidence of effects. We reviewed the global literature on the effects of rats on island flora and fauna. We then used New Zealand as a case study because of its four-decade history of rat eradications and many detailed and innovative studies of how rats affect native species. These include use of exclosures, local manipulations of rat populations, video surveillance, and measurements of responses following eradications. The most intensive studies have been on the Pacific rat (Rattus exulans), a small South-East Asian species spread by Polynesians throughout the Pacific. These and the more recently introduced Norway rat (R. norvegicus) and ship (roof) rat (R. rattus) suppress some forest plants, and are associated with extinctions or declines of flightless invertebrates, ground-dwelling reptiles, land birds, and burrowing seabirds. On islands off France, Norway rats are also implicated in declines of shrews. Globally, ship rats were associated with declines or extinctions of the largest number of indigenous vertebrate species (60), including small mammals such as deer mice and bats. Effects of rats on forest trees and seabird populations are sufficiently pervasive to affect ecosystem structure and function. However, the data are patchy. Deficiencies in our knowledge would be reduced by documenting distribution and abundance of indigenous species before and after eradications. Comprehensive measurements of the responses of indigenous species to rat eradications would enable the development of testable models of rat invasion effects.

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Section: Circumstantial Evidence Of Rat Effects In New Zealandmentioning

confidence: 99%

Have the Harmful Effects of Introduced Rats on Islands been Exaggerated?

2006

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“…Nonetheless, we recorded only 44 tuatara, no juvenile recruitment, a bias to large adults and evidence of declining body mass of females. These symptoms of catastrophic decline may reflect a longer history of Pacific rats on Taranga Island than the 200 years estimated for Lady Alice Island in the Marotere Islands (Brook 1999). Furthermore, assuming that the Taranga population comprises about 50 individuals, our matrix projections predicted that within 15–25 years they will be reduced to 10–20 scattered adults.…”

Section: Discussionmentioning

confidence: 95%

Responses of Tuatara (Sphenodon punctatus) to Removal of Introduced Pacific Rats from Islands

Towns¹,

Parrish²,

Tyrrell

et al. 2007

Conservation Biology

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Invasive mammalian predators such as rats are now widespread on islands, but hypotheses about their effects have rarely been tested. Circumstantial evidence from New Zealand indicates that, when introduced to islands, Pacific rats (Rattus exulans) have negative effects on endemic plants, invertebrates, birds, and reptiles, including the tuatara (Sphenodon punctatus). We tested the effects of Pacific rats on tuatara by comparing the demographic structure and body condition of tuatara populations on three islands before and after removal of rats and on a fourth island where rats remained. In the presence of rats, juvenile tuatara constituted on average 0-5% of the sample tuatara populations. When Pacific rats were removed after at least 200 years' occupancy, the proportion of juvenile tuatara increased 3.5- to 17-fold and body condition of adult males and females also improved (sometimes dramatically). We predict that, unless Pacific rats are removed from Taranga Island, the tuatara population will collapse because of low population density and the lack of juvenile recruitment. Our results demonstrate that when invasive species exert subtle effects on recruitment and body condition, the effects on populations of long-lived endemic species may only become apparent long after the invasion.

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“…1984, Meads et al 1984, Atkinson 1986, Parnsh & Sherley 1993, Brook 1999a There is circumstantial historical evidence from Motuopao Island that the kiore may have been an important predator ofthat S archevi population ) However, the declines and local extinction of S archevi populations at mainland North Island sites cannot be correlated with the coexistence of kiore The fact that the main overall decline in S aichevi distribution within northern New Zealand took place at least several hundred years, and possibly more than 1500 years, after the arrival of kiore (cf Holdaway 1996, Anderson 1996, suggests that predation by kiore was probably not a decisive factor European settlement of northern New Zealand led to considerably more profound environmental changes in coastal areas than had already happened in late prehistoric time Probably the most important changes affecting S archevi were those relating to the establishment of pastoral farming from the mid-19th century Impacts on dunefield habitats would have been cumulative, and included the modification and loss of native vegetation by firing, browsing and trampling by livestock, overplanting with exotics, and invasion by adventive weed species In addition, loss of vegetation cover through firing and livestock damage contributed to extensive erosion of some dunefields In the 20th century, some S archex i dunefield habitats were further modified or destroyed as a result of residential development and the establishment of exotic plantation forests…”

Section: Causes Of Holocene Population Decline and Extinctionmentioning

confidence: 96%

Changes in the landsnail fauna of Lady Alice Island, northeastern New Zealand

Cited by 32 publications

References 11 publications

Have the Harmful Effects of Introduced Rats on Islands been Exaggerated?

Have the Harmful Effects of Introduced Rats on Islands been Exaggerated?

Responses of Tuatara (Sphenodon punctatus) to Removal of Introduced Pacific Rats from Islands

Holocene distribution, ecology and local extinction of the endemic New Zealand dune snailSuccinea archeyiPowell (Stylommatophora: Succineidae)

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