The outer islands of the Antipodes Islands

Written by Juzah Zammit-Ross

View of Bollons Island. Photo by Kath Walker

View of Bollons Island. Photo by Kath Walker

The Antipodes Island Mouse Eradication operation will take place in the winter months of 2016 with the application of cereal bait Pestoff®20R by helicopter. The status of the outer islands will play an important role in the security of vulnerable terrestrial bird, invertebrate and plant species. Bollons Island is the only outer island that we have managed to visit so far as the rest are surrounded in steep cliffs. Recently we have declared confidence that there are no mice on Bollons Island and so it acts as an important sanctuary and reference for the biodiversity of the island group. Monitoring the other outer islands will determine whether mice are present or not, and this information will influence the extent of the treatment area for the baiting operation during 2016. Monitoring for the presence of mice on the outer islands of the Antipodes group is likely to occur in autumn 2015. If more of the outer islands are found to be mouse free they may also be home to some species no longer found on the main Antipodes due to predation and competition for resources by mice.

 Antipodes Islands

Antipodes Islands with outer islands marked with red arrows

Antipodes Islands with outer islands marked with red arrows

Outer islands:

Leeward Island – Area 12.5 hectare, located approximately 45m east of the main Antipodes Island. This island is to be monitored for the presence of mice in 2015.

Leeward Island. Photo by Kath Walker

Leeward Island. Photo by Kath Walker

East Windward Island – Area 8.5 hectares, located 540m north west of the main Antipodes Island. This island will be monitored for the presence of mice in 2015.

East Windward Island. Photo by Steve Horn

East Windward Island. Photo by Steve Horn

West Windward plus islet- Area 7 hectares, located approximately 1100m west of the main Antipodes Island. This island will be monitored for the presence of mice in 2015.

West Windward Island. Photo by Kath Walker

West Windward Island. Photo by Kath Walker

Orde Lees Islet –Area 1.8 hectares, located approximately 50m north west of the main Antipodes Island. This island will be included in the baiting operation in 2016 because of its close proximity to the main Antipodes Island. It is within the swimming range of mice.

Orde Lees Islet. Photo by Steve Horn

Orde Lees Islet. Photo by Steve Horn

Archway Island- Area 6.3 hectares, located approximately 1500m north east of the main Antipodes Islands. This island will be monitored for the presence of mice in 2015 to confirm the assumption that it is mouse free because of its distance from the main island and proximity to mouse free Bollons Island.

Archway Island. Photo by Steve Horn

Archway Island. Photo by Steve Horn

Bollons Island- Area 52 hectares, located 1500m north east of the main Antipodes Island. We are confident that this island is mouse free so it is an important refuge for terrestrial bird, invertebrate and plant species because of the lack of direct predation and competition for food resources. See the recent Blog on Bollons Island for more details.

Bollons Island. Photo by Kath Walker

Bollons Island. Photo by Kath Walker

Rock stacks – There are also 21 rock stacks within 600m from the main Antipodes Island and they make up an area of approximately 3.3 hectares in total. These rock stacks will be included in the treatment area for baiting due to their close proximity to the main Antipodes Island.

Rock stacks along coast. Photo by Kath Walker

Rock stacks along coast. Photo by Kath Walker

Monitoring tools used to assess whether mice are present or not on these outer islands will include tracking tunnels, traps and possibly the use of a rodent detector dog. Access in most of these cases is limited to helicopters.