Invertebrates

400 Tormissus guanicola. J. Marris

Tormissus guanicola. Photo by J. Marris

A feature of the Antipodes invertebrate fauna is the high percentage of species that are found around, or are restricted to, colonies of nesting sea birds. The guano enriched soil supports host plants, and feathers and detritus provide food and habitat for invertebrates.

Mice have had a significant impact on the invertebrates on the main island but have not been recorded on Bollons Island. The other  smaller offshore islands of the Antipodes group still need monitoring to determine their mice status.

The main invertebrates found in the gut analysis of mice captured on Antipodes in 1995 were Lepidoptera larvae (moths and butterflies family), and also arthropods (arachnid species or spiders).

The invertebrates collected on Bollons Island during the 1995 expedition allows a comparison between mouse-free Bollons Island and the main Antipodes Island, and so provides a unique opportunity to examine the impact of predation by mice on the invertebrate fauna of Antipodes Island. Two invertebrate species found on Bollons Island were completely absent on the main Antipodes Island, suggesting  probable local extinction most likely due to mouse predation.

Below is a table from Marris 2000, after the research trip to the Antipodes Islands in 1995. It clearly illustrates the impacts mice are having on the main Antipodes Island invertebrates particularly the larger beetles. Differences in Coleoptera abundance between Bollons Island and the main Antipodes Island are dramatic.

In most cases significantly more specimens were collected from Bollons Island in seven hours than from the main Antipodes Island in 26 days (Marris 2000).

Comparison of numbers of larger(>4mm) beetle species collected from Antipodes Island (over 26 days) and Bollons Island (over 7 hours)
Species (max. Length in mm) Antipodes Island Bollons Island
Kenodactylus audouini (4.8) 18 1
Loxomerus n. Sp. (11.8) 0 19
Oopterus clivinoides (5.6) 7 33
Tormissus guanicola (5.5) 0 8
Quediocafius insolitus (10.9) 3 15
Pseudhelops antipodensis (7.2) 3 0
Pseudhelops clandestinus (8.2) 5 50
Gromilus insularis antipodarum (5.4) 19 3

Read more about the effects mice are having on invertebrates. Read more

And more

Resources:

Antipodes Beetle species list

Marris, J(2000).The beetle (Coleoptera) fauna of the Antipodes Islands, with comments on the impact of mice; and an annotated  checklist of the insect and arachnid fauna. J Roy Soc NZ 30:169-195.

Russell, James, C. (2012). Spatio-temporal patterns of introduced mice and invertebrates on Antipodes Island. Polar Biology, Springer.

Taylor, R. 2006. Straight through from London, Heritage Expeditions New Zealand Ltd.

http://www.tandfonline.com/doi/pdf/10.1080/03014223.1994.9517457

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