Effects of a mouse, Mus musculus, eradication programme and habitat change on lizard populations of Mana Island, New Zealand, with special reference to McGregor's skink, Cyclodina macgregori

Published source details Newman D. (1994) Effects of a mouse, Mus musculus, eradication programme and habitat change on lizard populations of Mana Island, New Zealand, with special reference to McGregor's skink, Cyclodina macgregori. New Zealand Journal of Zoology, 21, 443-456.
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This study is summarised as evidence for the following.

	Action	Category
	Remove or control predators using lethal controls: Snakes & lizards Action Link
	Cease livestock grazing: Grassland & shrubland Action Link

Remove or control predators using lethal controls: Snakes & lizards

A before-and-after study in 1986–1993 on Mana Island, New Zealand (Newman 1994) found that following eradication of an invasive house mouse Mus musculus, the abundance of two of four lizard species increased, and two remained stable. Before-and-after comparisons were not statistically tested. In the four years following mouse eradication, the number of McGregor's skinks Cyclodina macgregori increased from one capture/100 trap nights in the year after eradication to 10 captures/100 trap nights three years after eradication. Numbers prior to eradication had been six captures (four years before), 8 captures (2–3 years before) and one capture/100 trap nights (one years before). Common gecko Hoplodactylus maculatus captures increased following eradication (after: 35–70 captures/100 trap nights; before: 5–15). Numbers captured remained similar for common skinks Leiolopisma nigriplantare polychroma (after: 6–10 captures/100 trap nights; before: 9–21) and copper skinks Cyclodina aenea (after: 2–4 captures/100 trap nights; before: 1–9). In 1989–1990, mouse eradication was carried out by distributing poison baits (Storm, Talon 20P, Talon 50W) via two aerial drops and ground baiting (over 5,000 stations in 25 m). In 1986–1987, cattle were also removed from the island. In 1985–1993, lizards were trapped annually (3–8 sessions/year; 2–4 days trapping/session) using pitfall traps (582–4,066 trap nights/session) that were deployed across 27 trapping stations around the island.

(Summarised by: William Morgan)
Cease livestock grazing: Grassland & shrubland

A before-and-after study in 1986–1993 on Mana Island, New Zealand (Newman 1994) found that following removal of cattle (and cessation of grazing), and subsequent eradication of an invasive mouse Mus musculus the abundance of one of four lizard species decreased, two remained stable, and one increased. Before-and-after comparisons were not statistically tested. Fewer copper skinks Cyclodina aenea were caught after grazing stopped (1–4 captures/100 trap nights) compared to before (9 captures/100 trap nights). In the four years following mouse eradication (when grazers were still absent), the number of McGregor's skinks Cyclodina macgregori increased from 1 to 10 captures/100 trap nights, though numbers were similar during grazing and in the first two years after grazing stopped (6–8 captures/100 trap nights). More common geckos Hoplodactylus maculatus were caught when there was no grazing and mice had been eradicated (35–70 captures/100 trap nights) compared to before eradication (15 captures/100 trap nights) and during grazing (5 captures/100 trap nights). A similar number of common skinks Leiolopisma nigriplantare polychrome were captured after grazing ceased (after: 6–21 captures/100 trap nights) compared to before (12 captures/100 trap nights). Cattle were removed from the island in 1986–1987, and the mouse population was eradicated using poison baits in 1989–1990. In 1985–1993, lizards were trapped annually (3–8 sessions/year; 2–4 days trapping/session) using pitfall traps (582–4,066 trap nights/session) that were deployed across 27 trapping stations around the island.

(Summarised by: William Morgan)