Determined criminals appear to be set on disrupting the otherwise successful predator control system put in place by the Hauraki District Trust on the Pauanui Tairua Trail.
In 2015 the trust purchased a small number of Good Nature traps for rats and stoats.
"These traps have destroyed about 30 predators during the past 12 months," spokesman Barry Gunson said.
"Three of these specially designed traps have been stolen at different times during the past few months. The cost of the traps is significant given that the trust is entirely dependent on donated funds.
"The thefts are bad news for the many supporters of the trail who welcome efforts to preserve birds and wildlife, including some endangered species.