Wellington's councils are putting a new twist on the idea of death by chocolate.
The regional and city council plan to use chocolate to lure rats into traps that will kill them instantly, to see how well rats can be controlled without poison.
The regional council's biosecurity team has set up several traps on Te Ahumairangi Hill, in the suburb of Northland.
Senior officer Paul Horton says because there are no possums in the area, it's an ideal site for focusing on rodents.
The chocolate lures can last six months and the trap can kill 24 rodents before CO2 needs to be replaced.
Urban Ecology Manager for Wellington City Council Daniela Biaggio said protecting biodiversity in urban environments needed continuous improvement.
"This is a great example of how we embrace new ideas and innovation so we can stay ahead of our biosecurity challenges and have a city thriving with wildlife."
The rodent numbers on Te Ahumairangi Hill are being monitored by tracking tunnels - cards in tunnels with ink on the floor that show footprints.
These are showing numbers remaining at low levels.
The site also has chew cards with peanut butter smeared on them. Bite marks left in the cards allow staff to identify which pests are present.