A recent study in Landsborough Valley run by the Department of Conservation shows that the number of native birds in this part of New Zealand has doubled.
The study has run for 20 years, examining the way in which birds respond to pest control. New Zealand aims to be predator-free by 2050 and this increase in the number of native birds looks as though it may be possible to achieve this. This is the longest-running study of its kind, starting in 1998 after the damaging impact of predators on birds was examined.
The Department of Conservation has been trapping predators such as rats, stoats and possums and has carried out aerial 1080 operations. Just two native birds saw a decline in numbers. These are the tautou – also known as the silvereye or waxeye – and the long-tailed cuckoo. Some such as the bush parrot, the wood pigeon and fantail have maintained steady numbers.
Others have seen dramatic increases. The Mohua has increased in numbers from 14 to 338 in just 20 years, which highlights the benefits of controlling pests. It is hoped that this work can increase as the department has been allocated additional funding of $181.6 million over the next four years.
The aim is to keep predator numbers under control and the $81.3 million that is to be allocated to this project will allow almost 2 million hectares of land to be predator-controlled. A number of other studies have been carried out that show that predator control has been more beneficial for some native birds than others. It is the deeply endemic species that appear to benefit the most, such as the kiwi.
This type of conservation work also tends to work better in fenced sanctuaries where it is easier to control the pests than in unfenced areas where the work simply aims to keep the pests at a low level.