It is hard to believe that the dreaded possum, scourge of our native forests, orchards and rose gardens, was once a protected species!
The Pukenui Forest Trust is currently removing as many possums as it can, using state-of-the- art trap and poison technology that is currently available.
Possum removal in the forest has been on-going now for several years, and the forest health has improved noticeably. One of the favourite foods of the possum in winter are the flowers of our beautiful kohekohe tree. This species is classed as sub-tropical and flowers in winter when there is not much other food about. Each flower has a small amount of nectar in it, which the possums love. Now, for the first time in quite a while, the kohekohe trees have flowered uninterrupted and are now setting seed.
Gerry Brackenbury, ranger, and volunteer Marcus Bax beside a hundred modified bait stations ready to kill rats and possums in the forest.
Another pest that has been chomping into the lower forest canopy are goats. Again, these wild animals have been living in Pukenui Forest for a long time, and now, over the last two years, professional hunters have removed up to 500 animals. This will allow the trees, the shrubs, the ferns and even the orchids to flourish once again.
Another major animal pest in the forest are rats. We have two species of European rats in NZ, rattus rattus and rattus Norvegicus, and between the two of them, they eat practically everything, including seeds, fruit, insects and birds eggs.
The combination of possums and rats has seen the almost total disappearance of native birds in the forest, particularly our beautiful native pigeon (kereru) and tui. These have been reduced to just a few birds when once they could be counted in their thousands. The pigeon is now the only bird left that has a crop large enough to cope with large fruiting trees like the taraire and puriri. If the pigeon disappears, what will spread the seeds of our trees?
Finally we cannot talk about pests and predators without mentioning the dreaded stoat. This was probably THE most stupid thing early colonists did to bring into the country this born-again killer. Stoats are highly intelligent predators which can swim, climb trees and leap tall buildings! This member of the mustelid family is the main reason why our kiwi have just about disappeared. Along with uncontrolled dogs, stoats kill kiwi on sight, especially kiwi chicks. We will be targeting stoats in our pest-control programme using a trap called a DOC 200. These will eventually cover most of the forest and, hopefully, within the next two years kiwi will be returned back to Pukenui Forest where they belong and can safely roam filling the night with their unique call.
Pukenui is close to the City of Whangarei and has been bordered by gardens
over a long period of time. Many species introduced by gardeners over
time have ‘jumped the fence’ and begun to invade our natural areas. Ginger,
climbing asparagus, Taiwan cherry, bangalow palms are some commonly found
species on the eastern slopes of Pukenui forest near the urban area. In
some areas invasive species have penetrated far into the forest, carried
there by wind, birds and sometimes trampers boots.
Invasive plants, especially those that form dense mats on the ground, have a long term impact on the forest. These plants change the food source and availability for birds and insects. Invasive ground cover plants prevent the establishment of seedling trees that will replace the forest giants when they eventually die. Invasive opportunist trees like Taiwan cherry and banglow palm often grow faster than our native trees and become the dominant species when light wells are formed from tree fall. Our native birds are adapted to the year round food source provided by native forest trees and plants.
Whangarei District Council is undertaking weed control in the Coronation Park area of the hills and encouraging the removal of invasive species from neighbouring gardens. Volunteers and small groups of residents have begun to work on the weeds on the border of the forest but there is much more to be done.
If you want to make a difference to the forest in your area, get a few neighbours or friends interested and form a weedbuster group. Contact the Pukenui Western Hills Forest Trust or Weedbusters for assistance.
Estimates indicate that more than 250 goats may be present in New Zealand's forests. Feral goats can have major effects on forest under-storey because of selective grazing pressure on preferred species. Goats can devastate the forest under-storey of preferred sites when undisturbed for long periods.
A feral goat herd lives above the Whau Valley dam reserve. Private-landowner control initiatives are reducing this population and it is considered that their control is relatively easy to achieve.
There is some good news re the goat control programme. By July 2011, the cullers had taken out up to 400 animals and the forest recovery is already starting to show.