Rats

There are two introduced European rat species in New Zealand; the Norwegian rat (Rattus novegicus) and the ship rat (Rattus rattus).

Rats are a threat to breeding birds as they prey on eggs and chicks. Ship rats are a particular problem as they are very agile and exceptional tree climbers. They can easily reach tree canopies, spending most of their times there hunting for nests to prey on. Our native birds did not evolve with rats and have no defences against them. Many native bird species also breed very slowly and cannot keep up with the present rate of predation.

The Department of Conservation carries out rat control in high value sites to protect endangered native species, such as kōkako and blue duck. The aim of this control is to keep rat numbers low enough to allow eggs to hatch and young birds to fledge. In areas where rat control occurs, there is often observed recovery of a range of native species like insect, snail, lizard and frog species, in addition to increases in the number of regenerating native plant seedlings (e.g. miro and hīnau). This illustrates the wide-ranging effects rats can have on biodiversity in natural areas.

Rats are widespread throughout the Waikato region.