Evie the rat dog
Trail cameras have shown that Norway rats are the worst predators of the eggs and sometimes the chicks of the braided river birds on the Ashley. But we are getting more and more evidence that feral cats are also a serious danger.
ARRG has traps spaced at 100m intervals along each side of the river for about 13 km, and another set that almost encircle the estuary. During the nesting season traps are emplaced around and among black-fronted tern nests and sometimes near wrybill nests. About 80 Norway rats were caught last year, but despite this, the rat problem continues.
It has become obvious that we need to hunt the rats: putting out traps and expecting the rats to walk in is insufficient. In the last couple of years on three occasions we have had a professional visit the river with rat detection dogs. The dogs proved their worth by finding many signs of rats, but it was clear that just a few days work each year was insufficient.
Detection dogs seem to be increasingly in the news in the last few years. They have been proven to be successful with many different invasive pests – animals, insects, plants – as well as drugs, cancer, covid and even electronics.
Valerie and I lost our pet dog a few months ago, and we decided to get a new one which would double as a rat detection dog. We got Evie, a Welsh Springer Spaniel, from a breeder and trainer of detection dogs who lives near Wanaka – Steve (Billie) Barton. When Evie arrived she was partially trained on rats, and Valerie has continued this training. The group has purchased a GPS unit and training collar – so we can track where she is, where she has been, and issue commands with beeps.
To date two hotspots of rat occurrence have been found. The most interesting is close to the Cones Road bridge. The rats are almost certainly there because of the pigeons that nest and roost under the bridge. There is an accumulation of broken eggs and remains of pigeons beneath the bridge. Feral cats are also drawn to this area, both because of the pigeons and the rats. Mice and possibly ship rats are also found under the detritus. The WDC have been approached about installing netting to stop the pigeons nesting. We hope to hear back from them soon.
Last nesting season, just north of the airfield, we lost an entire black-fronted tern colony and at least one wrybill nest to a combination of Norway rats and harriers. Norway rats are still to be caught under logs in this area.
Late last year Nick Ledgard found by accident rat burrows at dead animal carcasses on the berm downstream from Ashley Village. They were breeding a few tens of metres away. Over October and November thirty were caught in traps, including some very young ones. This was a very significant colony. Our hope with the dogs has always been to find such colonies, which are places where we can hit them hard and make a real difference. What we have found on the riverbed appears to be just pairs of rats breeding and it seems that we will have to carefully cover the berm to find large colonies. This will be a major exercise – fighting through the vegetation.
