Predator Control

An extensive network of nearly 500 possum traps extends right across the 2,000 hectares of the northern forest block in East Harbour Regional Park (EHRP) using two types of kill trap – Possum Master and Timms traps. These are baited with long lasting cereal bait and an attractant made up of flour, icing sugar and spices is spread around the traps. Traps are checked by volunteers fortnightly in most cases and monthly where catches are falling to very low levels.

In 2012/13 60 DOC200 stoat traps were added to possum traplines within and around the Mainland Island.

EHRP Catch data and bait consumption YE April 2015



In our 11th year of trapping another 269 possums have been dispatched bringing the total so far to 3538. The last 3 years have shown small but steady increases in possums caught.  It is uncertain whether this is a worrying trend or perhaps just a reflection of increased trapping effort in some areas.  Given the very high rat numbers experienced since the beech mast last season and increased targeting of possum lures by rats, a lower catch might have been expected in 2014/15. However the only objective measure of possums in the forest is the RTC monitor, which was last done in 2013 (2%). Time for another monitor?

Catch per trap again confirms what we have already observed in previous years that the eastern and northern boundaries are the source of the highest number of possums. A record of 17 possums was made on one single run on the south end of the Eastern Ridge this year. We need to give thought to strengthening these boundaries especially with regard to self-setting traps.

Other catch

Mustelid catches remain low and similar to the previous 2 years.

Rats are only bycatch in possum and stoat traps and increased hugely this year following the beech mast. However huge numbers no doubt got away based on the number of non-toxic lures taken from possum traps.

Feral cats have not been targeted in the last 2 years.

Rat Bait Consumption at Possum Traps:

As expected following the high beech mast, consumption of ditrac blocks at possum traps has soared to 8000 blocks this year. This matches the high reached in 2009/10 though still below the peak in 2006/07.

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