We are being very successful with our predator control work to protect our native wildlife from being eaten by rats, stoats and possums, but we should not forget the threat posed by browsing animals.

Seedlings and saplings are the youth of the forest, its next generation of plants. Browsing animals (deer, goats, pigs) definitely have their favourite foods and they can exterminate some species. This changes the diversity of the forest, snipping threads out of the food chain and affecting all the animals that are part of that chain.

Few king ferns (para) survive anywhere in the Kaimai ranges now. At Aongatete, a tangle of fallen trees protected a small pocket for many years. But, as the dead trees decayed and collapsed, the deer were quick to find the tasty ferns. That was when we stepped in and, with the help of the Tauranga Deer Stalkers Association, built the ‘king fern fence’. This exclosure now protects flourishing banks of ferns and is the source of the plants for a smaller demonstration plot of king ferns on the track near the car park.

The same fate has befallen the plant raukawa and its relation, five-finger. Their relative deliciousness means the only ones that survive are growing as epiphytes on tree ferns, safe from the reach of deer. These small trees have nectar-rich flowers and lots of berries and are particularly important for birds.

The effect of browsers is most graphically shown in the old weka aviary we build in 2007, between two of our baiting lines. This (photo above) is how it looks after 14 years – the undergrowth on the right of the shot is much thicker than in the forest around it. The palatable plants like hangehange and mapou have really flourished. Of course, possums and rats can still get inside this fenced area, so it’s only preventing the depredations of deer and pigs.

Deer also have a habit of rubbing their antlers on younger trees, and this image below shows a sapling that may not survive the de-barking damage.

– Ann Graeme