I thought this update would be valuable for any of you interested in large scale pest control over the 10,000ha South and North Okarito Forests in Westland National Park
----- Original Message -----
From: Wayne Costello
To: undisclosed-recipients:
Sent: Thursday, September 29, 2011 8:44 AM
Subject: Update - kea, kiwi, rats and stoats
Hi
I promised a couple of weeks back to keep you updated with results from the recent 1080 operation. What follows is a summary of our latest monitoring results and some more information about the effects of the operation. Please don’t hesitate to call me if you have any questions on any of the information below.
SMI
SMI stands for Small Mammal Index - it is the monitoring we do both inside the operation area (treatment) and outside (control) to ascertain what level of rats (and mice) and stoats are in the forest. Last week we re-monitored the SMI lines that we last did in August. We usually do this monitoring every three months (since 2001) - so we have some really good data showing the way rat and stoat numbers have changed over the last 10 years. In August the SMI showed that we had 29% tracking with rats and that 48% of our tunnel lines were tracked by stoats in the operation (or treatment) area.
After the 1080 operation the rat and stoat numbers have been reduced to 1% and 0% respectively. This is fantastic news and just what we were after. If you compare the results to the control areas (where no 1080 was laid) the rat numbers have increased dramatically to 95% and stoats present on 23% of tunnel tracking lines. Although the results of our SMI recorded no stoats - it is unlikely that we have eliminated all stoats in our treatment area - but hopefully we have killed a high enough percentage of the population in the kiwi sanctuary, and right around it, to significantly reduce the predation threat.
You may have read assertions that if we control the rats then stoats will switch to eating birds - and so 1080 operations are disastrous for forest bird species. As shown by the above results this is not the case and as expected and planned the stoats have been killed-off through secondary poisoning by eating the dead rodents. By taking out the possums as well - we will have had a massive and positive impact in our local forests, and the birdlife will reap the benefits - along with the insects, lizards and bats. The ecosystem will be much healthier as a result and the benefits should last for a while. The link below will take you to a short video that explains the research (ongoing) that supports this approach here on the coast.
http://www.youtube.com/watch?v=09y8uw5tV6o
So the operation has met its objective of reducing the rat and stoat numbers to extremely low levels in the operation area - this should allow our rowi to successfully recruit young chicks into the wild population.
By contrast the extremely high rat, stoat and possum numbers in the control (non-treatment) areas will mean that birdlife, insects, lizards - pretty much the whole ecosystem will take a significant hammering from these pests in the coming months.
Small Mammal Index Monitoring (SMI) involves setting out a large number of tracking tunnels in the forest (small corflute tunnels with blotter paper at either end and an ink pad in the middle). The tunnels are baited with peanut butter. Rats entering the tunnels leave their prints. The tunnels are set on lines randomly placed throughout the forest. The % indicates the number of tunnels that had been visited by rats (or mice) to give an indication of presence and abundance. After the first night the blotter paper is refreshed and bait changed to rabbit to monitor for stoat presence/abundance.
Rowi
Rowi are New Zealand’s rarest kiwi and currently our only method of successfully adding to the remaining 400 birds in the population is to take eggs from the forest, incubate, hatch and raise them in a predator free environment before releasing the chicks back when they are big enough to fend off a stoat attack. Even when we had over 2000 stoat traps in the kiwi sanctuary from 2001 to 2006 and stoat numbers were kept low we still lost nearly every (95%+) chick that hatched to stoat predation. Stoats are very efficient killers - in fact killing machines, which is why the Parliamentary Commissioner for the Environment in her report evaluating the use of 1080 described them as: “the ‘perfect predator’; birds that nest on the ground or holes on trees have no escape.”
So far we have received data from Sky Ranger of 20 rowi pairs incubating eggs. The first of these eggs was due to hatch yesterday - so we’ll let you know how this chick gets on. Over the next month another 12 odd chicks should hatch - if everything goes well during incubation and if all the eggs are viable. Some of the remaining 7 eggs we currently know of will be picked up and taken to the West Coast Wildlife Centre for incubation and hatching as the rowi pairs with these eggs are known to be good breeders and are likely to lay again. We will leave this second egg in the wild and monitor once the chick hatches. Our target is to monitor 20 to 25 rowi chicks through their first 12months.
I’ll keep you posted on the progress of this work and the monitoring of the chicks in the sanctuary. It is our goal is that the 1080 operation will result in wild chick natural recruitment into the rowi population, but we have to be realistic and remember that even one ‘perfect predator’ left - will kill defenceless rowi chicks. In Tongariro where kiwi were monitored after a 1080 operation 69% of chicks survived compared to 27% surviving prior to the 1080 operation.
Kea
As detailed in my last email - we unfortunately lost 7 kea to 1080 poisoning as a result of this operation. We were monitoring 37 kea in the operational area, so 81% of monitored kea survived. Some erroneous figures have been put out there to enhance various spurious claims - but the information I have provided here is accurate.
We have continued to monitor kea after the operation using Sky Ranger and there have been no further losses and all the birds appear to be doing well. We have 9 nests currently monitored within the 1080 operation area and 5 monitored in the non-treatment (control) area. Because we have reduced stoats, possums and rats to low levels, kea in the operation area should have an improved and successful breeding season - again I’ll keep you posted on the results. It takes 4 months for a kea nest to successful fledge chicks - so the results of the monitoring will be known by February next year.
Already in the non-treatment area where 1080 has not been used - one of the nests that we are monitoring has been predated - killing both young chicks. Our research has shown that 60+% of kea nests in this area fail - predominantly due to predation by stoats or possums.
We are continuing our work to reduce risks to non-target species and progressing trials of bird repellents in baits used for possum and rat control. I will endeavour to keep you updated with this work and our ongoing monitoring through our newsletter - Making Tracks.
Meanwhile - if you have any questions or would like to learn more about our work, or this operation, please do just give me a call.
Kind regards
wayne
Wayne Costello
Area Manager — Poumanahere
Franz Josef Waiau Area
Department of Conservation — Te Papa Atawhai
DDI: +64 3 752 0794 | M: +64 22 009 2963
Conservation for prosperity Tiakina te taiao, kia puawai