The Problem

3Mice are the only introduced mammalian pest on the main Antipodes Island. The first published reference to mice on Antipodes Island was in 1909. They may have been introduced from a ship wreck or from one of the many sealing trips to the island following the island’s discovery in 1800. The unique haplotype of the island’s mouse population is not found in NZ but has affinities to Spain (Russell 2012).

Mice are now abundant on the main Antipodes Island and are at high densities, particularly in highly productive food sites like the dense coastal tussock.  The density of adult mice on the island in winter 2013 (104 mice/ha at Reef Point and 74 mice/ha at North Plains) was not significantly different from the adult density that was previously recorded in January 2011 by Russell (2012) (83 mice/ha at Reef Point and 55 mice/ha at North Plains). This may be due to winter 2013 having been incredibly mild on the island—also being the warmest winter on record for New Zealand (at the time of writing).

Mclntosh (1996) recorded up to 117 catches/100 trap nights in November 1995 on Antipodes Island around the coastal penguin colonies. Mice were present in low abundance on the high altitude site on Mt. Galloway.

The average home range of mice on Antipodes Island was estimated at 20m radius for females and 30m radius for males during the July 2013 trials.

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Mouse breeding appears to almost, if not completely, cease at midwinter on Antipodes Island and recommence breeding in late August.

Mice are exerting strong ecological engineering impacts on Antipodes Island, predominantly through direct impacts on invertebrates, and likely flow-on, although less well understood indirect impacts, on vegetation and land birds. Read more

The abundance of Black-bellied Storm-Petrels (Fregetta tropica) on Bollons Island relative to their extremely low density on Antipodes could be evidence of the impacts of mice (Angel et al., 2009, pg. 1748). The impacts of mice on Antipodes will likely increase with warming winters.

Monitoring of the four endemic terrestrial bird species in August and October 2014 on Bollons Island anecdotally confirmed earlier observations by Taylor in 2006, that Antipodes Island parakeet, Reischek’s parakeet, Antipodes Island pipit and Antipodes Island snipe are significantly more abundant on the mouse free island than on the main Antipodes.

An increase in similar terrestrial bird species post eradication has been seen on other similar islands. For example snipe were absent from Campbell Island in the presence of rats and rare on Enderby Island in the presence of mice. Snipe are now commonly sighted on both islands following respective eradications and subsequent natural recolonisation or recovery. Pipit on Campbell Island went from being rarely seen (i.e. a single sighting per year) pre rat eradication to being a common species seen multiple times every day in every habitat.

Comparative studies of mouse-free and mouse-invaded island pairs (Bollons-Antipodes and Prince Edward-Marion) strongly suggest that mice have a major impact on invertebrates at three levels: species composition, relative abundances and size distributions (Angel et al, 2009. pg 1747). The negative impact mice are having on invertebrates in particular large beetle species was confirmed through research conducted on the islands in 2000 (Marris 2000) and by Russell in 2011 and 2012 (Russell 2012). Both conducted invertebrate research that highlighted the difference in composition and abundance/presence of invertebrate species between a mouse free island of the Antipodes group and the main Antipodes Island. From mouse gut samples taken during research by McIntosh (1996) and Russell it was confirmed that mice eat vast numbers of invertebrates and seeds. A good example of the impacts that mice can have on seabird populations has been noted on Gough Island.

Internationally, as at December 2014, 97 eradications of mice have been attempted on 87 islands of which 71 were successful (73%). The largest of these were Macquarie Island at 12,800ha (DIISE database).

Learn more about rodent eradications. 50th Anniversary of rodent eradications in New Zealand

 

Resources:

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Angel A., Wanless R.M.,Cooper J. 2009. Review of impacts of the introduced house mouse on islands in the Southern Ocean: are mice equivalent to rats? Biol Invasions, 2009, 11:1743–1754.

Marris, J. W. M. June 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. Journal of The Royal Society of New Zealand, Volume 30 Number 2, pp 169-195.

Russell, James, C. 2012. Spatio-temporal patterns of introduced mice and invertebrates on Antipodes Island. Polar Biology, Springer. 35:1187–1195.

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