By Ian Bradford

I’ve watched some of the episodes on TV1 of “Fight for the Wild”.  This is basically about volunteers in various areas of the country setting traps for so called predators in order to save the birds. I don’t really have any complaints about this. Although volunteers are involved, money still has to be spent on traps and baits. However, the good thing is that traps are being used and not 1080.   

Possums are not predators

I disagree with possums being lumped with the predators. Possums are much maligned. While there are a few rogue possums, in the main they are vegetarians.

The last figure I had from two years ago, was that the possum fur industry brings in a revenue of about $170 million dollars per yearThe possum fur industry cannot get enough fur. 

It is much better to leave the trapping of possums to those who want to make a bit of cash out of the fur. I wonder what these volunteers do with the dead possums they find in their traps. Do they simply throw them into the bush or do they carry them out and extract the fur?  I suspect the former. If so, then what a waste.  

Propaganda on 1080

As expected, the programme tried to justify the use of 1080 to kill the predators. There are many parts of the country where it is not possible to catch so called predators in cages. I regarded this section of the programme as pure propaganda. It was interesting that they were poisoning a rat with 1080 then leaving that rat at a point that a stoat would frequent. It is well known that stoats prefer rats for food. The stoat would then eat the rat and die of secondary poisoning. 

I am university science qualified and have spent most of my life roaming in NZ forests

I and many others have said for years that many birds have died from secondary poisoning. (We have all seen hawks eating dead possums killed on the road).  There is nothing to stop such birds as kea, hawks, kiwi and so on, eating a dead rat which contains 1080 just like the stoat.  

In fact my cat used to catch rats – fortunately in an area where no 1080 was dropped. Weka would eat the rats left on the lawn by my cat. If the rats had been poisoned by 1080 then the weka would have died also. 

End of the dawn chorus

I first entered Nelson Lakes National Park in 1969 to look for a deer. I camped overnight up one of the valleys from Lake Rotoroa. I arose early next morning.  As I waited for a little bit of light the birds began their song. The sound eventually reached a crescendo. The so called dawn chorus was deafening. I had never heard anything like it. It was absolutely amazing. 

The trouble was as we entered the 1970’s and beyond, the dawn chorus faded till it was almost non-existent. Sadly, since that time I have not heard anything like what I heard that morning. 

Introduced predators

The three predators always named are the possum, the rat and the stoat.  You will read that the rat was introduced around 1300 AD with the arrival of the first Maori.  However, rats have been found in strata, dated some hundreds of years before Maori arrived.  Evidence of a pre-Maori population. 

Stoats were introduced in the 1870’s to control the rabbit population.  Possums were introduced in the 1830’s initially but didn’t survive, so a further lot was introduced in 1858. So by the time I entered the park in 1969 possums and stoats had been in our forest for a hundred years and rats for a very long time. It is fair to say there must have been lots of them. 

Now between 2000 and 2020 there were about four masts. (A mast is when there is an excessive beech tree seeding.) This provides extra food for rats. So between 1870 and 1969, just on a hundred years, on average there would have been 20 masts.  Interesting that the birds managed to survive these.  

Interesting too that although rats, stoats and possums were all through the forest for a hundred years, (though in the early years numbers were still building), that there was an abundance of birdlife in 1969. 

Now the pro -1080, against the predators lobby would say “Oh you probably made all that up about lots of birds in 1969.”  I can assure the readers that what I’ve written above is the absolute truth. 

Upsetting the equilibrium of the forests

There is some confirmation of my cnclusions. I was prompted to write this because of a short programme on TV1 a few weeks ago. DOC were returning some Kiwi raised in captivity to the West Coast. What I found of interest was an interview with an elderly couple. I suspect most people probably missed the point in this interview. The couple said they were very pleased to have the kiwi back again. Then they said they used to sit on their veranda in the 1950’s and listen to the kiwi in the bush. Through the 60’s and 70’s these calls of the kiwi gradually disappeared. So here we have seemingly many kiwi present in the bush in the 1950’s  along with lots of rats, stoats, and possums. 

What is my explanation of this?  I believe there was an equilibrium in the forest. Not long ago I found a good example of the equilibrium having been disturbed. 

The local council decided to poison the rabbits at the mouth of the Taieri River south of Dunedin. Now the hawks in the area fed on young rabbits. With the rabbits gone the hawks then turned to fledgling birds for food. The poisoning had destroyed the equilibrium to the detriment of the birds.  

Rats and stoats probably did take some birds. But because there were many birds, the effect was not felt.  Let me give a simple example. If there are 100 birds and a stoat takes one that is only a 1% loss.  If there are only ten birds and a stoat takes one, then that is a 10% loss. 

1080 has killed birds

So what caused the loss of birds in the first place? I have just completed 50 years of roaming in two national parks and in particular Nelson Lakes National Park.  I lived literally on the boundary of this park for the past twenty years. I don’t have the slightest doubt that 1080 has seen the demise of our birds. Because this dreadful chemical has reduced our bird population to low numbers, the effect of stoats and rats has been much more pronounced – the 1%, 10% effect. So we entered a downward spiral. More 1080 used because bird numbers were getting low. We had to kill the predators, said DOC. 

Landcare Research found and published, that after a 1080 drop, rat numbers – (the biggest bird predators) were reduced to somewhere between 10% and 20 % of the numbers before the drop. But they also found that two years after the drop rat numbers were at least twice what they were before the drop. Meanwhile, in that year after the drop stoats ate more birds because their favourite food – the rat – was in low numbers. So a 1080 drop actually produced more rats. So we continually lost birds to predators and of course to secondary poisoning from birds eating poisoned animals.        

It will be a long hard slog to restore bird numbers again and only if no more 1080 is dropped.