Wildlife Foxton Trust has been formally warned by the Ministry of Primary Industries for leaving animals to die in live capture traps rather than releasing or humanely destroying them.
An MPI spokesperson said the trust failed to meet its obligations under the Animal Welfare Act.
In February, MPI received a complaint about live capture traps that had animal remains in them in Foxton's Palmer Road area.
MPI investigated as the reports indicated the traps were not checked daily and captured animals were left to die in them.
The spokesperson said the public interest was best served by issuing a formal warning to the trust.