Introduced predators - by the numbers

Last updated 09:38 16/11/2012

Many of you will know that I am a staunch proponent of predator-free areas to give our native wildlife a shot at survival.  However, because of the shifting baselines of how bad things have got and how hard some facts are for us to get our head around (e.g. can you believe kakapo were once one of New Zealand's most common birds, found from Cape Reinga to Bluff?), it can be difficult to impress on others just what is at stake here. Today I've decided to take a "by the numbers" approach to how mammalian predators have affected our native species.

Possum

This remote-captured image is of a possum and rat eating thrush chicks near Waikanae, but picture this every night in every corner of our forests and the impact on our native birds. (Photo: Nga Manu images.)

26,000,000 - native birds (and eggs) estimated to be killed by predators in New Zealand every year. (You can read the scientific paper on this here.)

11,000 - hectares declared predator free on Campbell Island in 2005.

500 - the number of kiwi killed by a single roaming dog over six weeks in Northland in 1987.

kiwi killed by dogs and cars (DOC)

These Northland kiwi have mostly been killed by dogs (some by cars). In Northland, dogs (pets, hunting dogs, any dogs!) are the No 1 threat to kiwi.

126 - kakapo remaining on the planet (it was 50 in 1991; only rescuing them from introduced predators such as cats, rats and stoats has saved them).

kakapo killed by cat (DOC)

These are the remains of a Stewart Island kakapo that was killed by a cat (before the birds were transferred to safe islands). (Photo: DOC.)

72 - lizards found inside one feral cat in Central Otago.

inside of feral cat Tuhaitara Coastal Park (Greg Byrnes)

These skinks were found in the belly of one feral cat at Tuhaitara Coastal Park last month. (Photo: Greg Byrnes.)

13 - A dirty (baker's) dozen of introduced predatory mammals making life hard for our native wildlife (mice; rats - three species; weasels; stoats; ferrets; hedgehogs; possums; cats; pigs; and dogs).

1 - species of bat (the greater short-tailed bat) that has gone extinct due to introduced mammals.

Greater short-tailed bat

The only photograph of a greater short-tailed bat, which went extinct on Big South Cape Island near Stewart Island after a rat plague in the 1960s. (Photo: Don Merton, DOC.)

And now for some percentages...

12% - the amount of public conservation land now under any kind of sustained pest control.

Which means;

88% - of public conservation land with little to no pest control.

95% - the proportion of North Island brown kiwi chicks that do not survive in areas with no pest control.

(You can see where I'm going with these figures, can't you?)

What does that mean for you and me? That our native wildlife needs all the help it can get. Get involved in a local trapping scheme and let's give something back to those creatures we love that form the backbone of our national identity.

Did you realise things were that tough out there for our native animals? Are you involved in some kind of pest control? I'd love to hear about it.

» Please feel free to email me to send me your questions, feedback, ideas or photographs for In Our Nature blog posts. You can also join the In Our Nature Facebook page.

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