Cats: top predator? NOT TRUE!

The following is a comprehensive, well-researched study of predatory animals and their behavior in New Zealand. This research indicates that cats are the least of Raglan's problems as related to bird predation. Read and learn!

Cats: top predator?

The idea that Cats must Go, put forward by Gareth Morgan fails to take account of the multiple predators introduced to New Zealand over time. A fairly cursory look at Te Ara produced the following information, which puts the predation by cats in perspective. You may be surprised to find that the cat is an ‘also ran’ usually beaten out of first place by rats and mustelids (stoats and weasels). Don’t believe me? Check out the original entries in the Encyclopedia. You will find that I have faithfully copied the information across.

 Excerpts from Te Ara, The Encyclopedia of New Zealand.

{Kiwi} Predators

Because kiwi hatchlings are left at such a young age, they are vulnerable to predators. It is speculated they might have become nocturnal to avoid the Haast’s eagle, now extinct.

Introduced animals are a more severe threat. The most dangerous are stoats, which feast on the young birds. Kiwi chicks can resist stoat attacks once they weigh about 1 kilogram, but this is not until they are 40 weeks old. Other predators include dogs, feral cats and even wild pigs, which dig up kiwi burrows. Weka are known to eat kiwi eggs.

Only about 5% of wild kiwi chicks survive the first six months. Once there were an estimated 12 million kiwi, but by 2006 there were fewer than 100,000.

Jock Phillips. 'Kiwi', Te Ara - the Encyclopedia of New Zealand, updated 30-Jan-13 
URL: http://www.TeAra.govt.nz/en/kiwi/sources

{Rabbits} Trying to control Rabbits, Methods that have been tried include: …

·         using predators such as ferrets, stoats and weasels. These were released in New Zealand, but they hunted native birds, and did not kill as many rabbits as expected

….
Robert Peden. 'Rabbits', Te Ara - the Encyclopedia of New Zealand, updated 9-Nov-12 
URL: http://www.TeAra.govt.nz/en/rabbits

{Lizards}

Predators

Mammal predators pose the biggest threat to native reptiles. Kiore or Pacific rats (Rattus exulans) arrived with Polynesians about 1250–1300 AD and caused the extinction of some lizards on the mainland and on the smaller islands. In the late 1700s and early 1800s, European rats, mustelids (ferrets, stoats and weasels) and cats caused another wave of local extinctions.

Extinctions

At least three lizard species have become extinct since people first discovered New Zealand. Eight species have become extinct on the mainland but survive on islands where there are few predators. Those surviving on the mainland are less common than they once were.

Large, nocturnal species are most likely to become extinct, as mammalian predators usually hunt at night. For example, all large species in the genus Oligosoma are nocturnal. Large species are all but restricted to rat-free islands, and small species still occur on the North Island. All were once widespread across the North Island. Even large, day-active lizards are vulnerable to predators and today occur only in small, widely separated populations – just a portion of their original range.

Endangered species

Almost half of New Zealand's reptiles are threatened or endangered. It is now illegal to handle or keep in captivity any native lizard without a permit from the Department of Conservation.

Some, such as the spotted skink (Oligosoma lineoocellatum), are still widespread, although their numbers are probably dwindling. Others are endangered, including the Otago and grand skinks, two of the country’s largest (up to 30 centimetres long). They live in mountain tussocklands in Central Otago, but occupy only one-tenth of their original range. The reason for this is unclear. They may have fallen prey to cats, especially in winter, when cats are hungry and lizards slow. Natural fires and agricultural development are also threats. Research is under way to manage these hazards and help these species recover.

Until recently there have been few attempts to save endangered or rare reptiles from extinction. The eradication of rats from islands such as the Mercury Islands off Coromandel Peninsula has brought new hope for some lizard species. Rats are well controlled by cat populations.

Kerry-Jayne Wilson. 'Lizards', Te Ara - the Encyclopedia of New Zealand, updated 9-Jul-13 
URL: http://www.TeAra.govt.nz/en/lizards/sources

{Weta}

Giant wētā

Giant wētā (genus Deinacrida) are predominantly herbivorous. They are not as social as tree wētā and tend to occupy temporary, poorly protected shelters by day, which exposes them to predators.

Giant wētā did not survive long in lowland areas after the arrival of humans and rats in New Zealand. Of the 11 giant wētā species, only six still occur on mainland New Zealand – in the South Island mountains, above the level where rats live. The other species now survive only on offshore islands.

Wētāpunga

The most impressive wētā is the wētāpunga (Deinacrida heteracantha), a species of giant wētā now confined to Little Barrier Island. Females reach a body length of 7.5 centimetres, and their hind legs are 13 centimetres if stretched out. Like other lowland giant wētā species, these giants of the insect world were extinct on mainland New Zealand by 1900, killed by rats.

George Gibbs. 'Wētā', Te Ara - the Encyclopedia of New Zealand, updated 30-Jan-13 
URL: http://www.TeAra.govt.nz/en/weta/sources