A rat plague currently sweeping the country will almost certainly be followed by a stoat plague, with potentially disastrous results for Northland's kiwi population.
Northland pest control firms are reporting a surge in the number of rats this winter — some say they are twice as busy as this time last year — while conservation groups such as Paihia's Bay Bush Action say they are being inundated with a ''rat tsunami''.
The cause is thought to be a mega-mast, when many species of native trees mast, or produce large quantities of fruit and seeds, at the same time.
Rodents gorge themselves on seeds, breed prolifically, then invade people's homes and prey on native wildlife once the seeds are gone.
Andrew Mentor, Kiwi Coast co-ordinator for the Mid North, said conservation groups around Northland were reporting large numbers of rats.