An unwelcome Christmas present was delivered to Shakespear Open Sanctuary when rat footprints were detected in a tracking tunnel.
Rats are a threat to vulnerable native wildlife, including many of the bird species that now live within the open sanctuary.
The footprints were spotted during regular checks of the tunnels, around Christmas.
The tunnels contain bait, and inkpads with a piece of card. The animals walk across the inkpad and leave their prints on the card en route to the bait. The tunnels are checked at least monthly.
Open sanctuaries senior ranger Matt Maitland says the rat prints were found in a tunnel near the Waterfull Gully entry area, not far from the pest proof fence.
Whenever an incursion is detected, a standard package of tools is activated which includes kill traps and bait stations which are able to be loaded with the poison Brodifacoum for the period of an active incursion only.
“We then sit back and wait,” Mr Maitland says. “Ideally we get an animal caught in a trap and when that happens we carry on with the incursion response for a month after the last find.”
However, the alternative is that the rat left the sanctuary by itself or succumbed to poison – either of these mean there is no proof of the incursion being over.
It has been several weeks since there was any sign of the rat, so next month, provided there are no further signs, the incursion response will be stood down to a ‘low watch’ level.
So far, no damage from the incursion has been noticed – Mr Maitland says a good indicator are any problems related to birds such as the North Island robin and saddlebacks which are especially vulnerable to rats as they are often on the ground.
He says very young kiwi chicks can be susceptible too, or a rat could disturb an adult kiwi as it sits on an egg.
“It’s been the best part of a year without a rat coming in, and that’s a good long time,” Mr Maitland says.
“Trapping in the buffer zone before the fence, and the natural topography at Shakespear have helped with that. We have also learned some good lessons from Tawharanui Open Sanctuary which has around 4-6 rats come in each year.”
“We back ourselves to detect and remove these pests before harm has occurred. There have been one or two invader rats per year for the last few years, all of which have been successfully detected and removed before establishing breeding populations or causing significant harm to the native species we are seeking to protect within the open sanctuary. A single incursion is not good, but the real worry is a population establishing.”
He says it’s timely to remind visitors to let rangers or SOSSI know if they see or suspect animal pests within the open sanctuary. Visitors should also take care to check belongings prior to visiting to prevent unawanted pests hitching a ride.
This recent photo of kakariki nesting in Waterfall Gully illustrates the danger posed by rodents in the sanctuary. Hole nesters like kakariki (red crowned parakeets) can easily be ‘cornered’ in the cavity by predators, and can’t escape. Mr Maitland says that successful breeding of species that nest like this in holes or on the ground are far more likely to be successful in predator free areas like Shakespear. Photo, Donald Snook/SOSSI