Trelissick Park Group: Predators

As well as keeping plant pests (weeds) under control in Trelissick Park, there are continual efforts to control animal pests (predators). The Wellington Regional Council (Greater Wellington) has been very proactive for many years in regional predator elimination and control, as has the Wellington City Council in city parks and reserves.

Pest animals in Trelissick Park

The regional council introduced bait stations into Trelissick Park in early 1998. As a result, there has been very little evidence of possum activity in the park for the last 25 years, though possums were once a great menace to native plant regeneration. For background information on this see Trelissick Park possum control, 1999 (PDF).

There are ongoing problems with rats, stoats and other mustelids, hedgehogs, and rabbits. Of particular concern are rats and stoats which kill native birds and eat the eggs in their nests. To a lesser extent, mice can be considered predators, as well as feral cats, and some domestic cats on park boundaries near residential areas. Dogs off-leash, off-track and not under control can be fatal for fledgling native birds. And it should be mentioned that there are a very small minority of the human visitors to the park who damage or destroy the native fish and eels and the native birds or their habitat.

Pest species in the park can include:

Possum – Trichosurus vulpecula
Ferret – Mustela furo
Stoat – Mustela erminea
Weasel – Mustela nivalis
Norway rat – Rattus norvegicus
Ship rat – Rattus rattus
Hedgehog – Erinaceus europaeus occidentalis
Hare – Lepus europaeus occidentalis
House mouse – Mus musculus
Feral rabbit – Oryctolagus cuniculus
Feral and unwanted cats – Felis catus
Off-leash and off-track dogs – Canis lupus familiaris

Research on animals in the park

In September and October 2017 a Victoria University MSc student conducted a study of animal intruders into an area of Trelissick Park using a dozen motion-activated cameras. The cameras were sited 10m or 20m off track to avoid filming any track users. Around 40,000 images were recorded and evaluated.

The numbers of confirmed free range animals (excluding birds) were:

9 rodents
56 hedgehogs
337 dogs
50 cats
68 rabbits
0 mustelids

You can read more about the project in the reports below.

Project summary (November 2017) (PDF)
Project final report (December 2017) (PDF)

Earlier monitoring trials by Victoria University using chew cards, tracking tunnels, and night motion-sensitive videos identified interesting pest animal behaviours and distribution patterns. There were 60 chew card locations on three chew lines. The locations were visited monthly for a year to replace the chew cards and to ascertain which predators had visited.

Chew card locations map (July 2012 update) (JPEG)

Video showing rats at a bait station in Trelissick Park (2012).

TPG volunteer efforts

In 2008, TPG volunteers took over bait station servicing, in partnership with the city and regional councils, and mustelid traps (DOC200) were introduced. Volunteers regularly visit the bait stations and the traps to check and replenish or reset them.

We currently have 8 volunteers, who do regular (often monthly) rounds of their allocated traps and bait stations when they can.

We have 28 bait stations, 17 DOC200 mustelid traps, 15 A24 stations, and 20 Bait Safe possum stations (serviced by the Regional Council). The possum and rodent bait for many years was pellet bait. In 2016 the bait was changed to block bait to lessen the chances of pellets being dislodged from the bait stations and of rats hoarding them. The block bait is designed mainly for rodents.

The locations of bait stations and mustelid traps are shown on the following maps.

In addition to these we have 10 Victor rat traps in wooden tunnels located between the Oban bridge and the debris trap. These were installed by Scots College students in the winter months of 2022.