The Enemies

 

Brush-tailed Possum (Trichosurus vulpecula)
Possums damage our native forests by browsing on trees, seedlings and regenerating plants. Their feeding habits can result in some plants like rata being eaten out of the forest, or in severe cases it can cause the complete dieback of forest canopy. Possums are also known to predate on native birds, eggs, chicks and native land snails.

They’re small, they’re furry, they’re introduced and they’re killing Bluff’s native bird and plant life. Possums, rats, ferrets, stoats, weasels and feral cats all take their toll under cover of darkness.

Feral cats (Felis sylvestris)
Feral Cats are known to predate on New Zealand's native land and sea birds, as well as various lizard and insect species. On Bluff Hill cats pose a significant threat to nesting titi and to little blue penguins.

Ferrets, Stoats and Weasels
Ferrets, stoats and weasels (collectively called mustelids) are all bad news for birds. But how do you tell them apart?
Ferrets (Mustela furo) are the largest of the three species in New Zealand, with males weighing around 1kg. Their coat is variable in colour with a mask of dark coloured fur is usually present across the eyes.
Stoats (Mustela erminea) are smaller than ferrets with males up to 300 mm long and weigh around 350g. Their fur is reddish brown with a creamy white belly. They have a distinctive bushy black-tipped tail
Weasels (Mustela nivalis vulgaris) are the smallest and least common mustelid in New Zealand at about 200mm long. Their fur is brown with a white belly often broken by brown spots. Their tail is short, brown and lacks the black tip that the stoat has. Mustelids are devastating predators that threaten the long term survival of many New Zealand native species. Mustelids will kill almost anything from native bats to freshwater fish. They are major predators of virtually all native birds on Bluff Hill including kaka, kereru, tui, morepork, titi, kakariki, fernbird and shags.

Rats (Rattus norvegicus and Rattus rattus)
Norwegian Rats (R. norvegicus) are the largest rat in New Zealand. Norway rats are often associated with wet areas such as rivers, streams, drains, lakes, lagoons, swamps and estuaries. They will also occupy buildings where there are suitable nesting conditions and food. Norway rats often dig burrows 60-90 mm in diameter.
Ship Rats (Rattus rattus) are one of the most common mammals in New Zealand, but being shy and nocturnal they are seldom seen. Ship rats do not dig burrows like the Norway rat, instead they use existing refuges. Ship rats are excellent climbers and are better able to exploit bush habitats than Norway rats.
Rats are very productive breeders enabling them to rapidly reach large populations when food is abundant. Rats reduce forest health through eating flowers, fruit, seed, seedlings, native insects, lizards, bats, birds and their eggs, causing population decline or even extinction.

Little blue penguin killed by a stoat. (image courtesy of DOC)

Weasel

Stoat

Stoat

Ship rat eating fantail chick (image courtesy of DOC)

Seven skinks found in a feral cat's stomach (image courtesy of DOC)

 

Possum

Feral cat

Hedgehogs (Erinaceus europaeus occidentalis
Hedgehogs were introduced to NZ in the 1870s along with many of the other mammalian predators. They are cute and harmless looking, but unfortunately cute and harmless needs to eat. Hedgehogs are mainly insectivorus but are happy to munch on anything, this includes mice, lizards, frogs and birds' eggs and chicks. They therefore damage our fragile native ecosystem in two ways; by direct predation on the birds and by gobbling our native insects, many of which are an essential food source for the birds and pollinators of the plants. It is estimated that an adult hedgehog consumes an average of 160g of food per day. Hedgehogs are killed in the stoat traps.