Waingake Bush Pest Control and Monitoring Implementation Plan - Appendix 1 & 2
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Appendix 1 & 2
Waingake Bush Pest
Control and Monitoring
Implementation Plan
Report prepared for Gisborne District Council by Abigail Salmond.
April 2018
A878686 1Contents
1. Background and Summary ................................................................................................................... 3
2. Establishing animal pest management goals and objectives for Waingake ............................. 5
3. Pest control and monitoring at Waingake......................................................................................... 6
3.1. Background .................................................................................................................................... 6
3.1.1. Change in pest control focus ............................................................................................. 6
3.1.2. Beech mast seeding ............................................................................................................. 7
3.2. Landcare Research Report ......................................................................................................... 7
3.2.1. Landcare report Summary .................................................................................................. 7
4. Pest control and monitoring implementation ................................................................................. 11
4.1. Pest monitoring .................................................................................................................................. 11
3.1.1. Camera traps ....................................................................................................................... 11
3.1.2. Baited chew cards .............................................................................................................. 13
3.1.3. Trap catch rate for stoats .................................................................................................. 13
3.1.4. Catch rate for goats ........................................................................................................... 14
4.2. Pest control ......................................................................................................................................... 14
4.2.1. Option one (preferred option proposed by Landcare). .................................................... 15
4.2.2. Option two ................................................................................................................................... 17
4.2.3. Option three ................................................................................................................................ 18
4.3. Outcome monitoring .................................................................................................................. 19
4.3.1. Bird count .............................................................................................................................. 20
4.3.2. Vegetation plots .................................................................................................................. 21
4.3.3. Bat monitoring ...................................................................................................................... 22
References ..................................................................................................................................................... 23
Appendix 1. Pest control and monitoring five year budget. ........................................................... 24
Appendix 1.1. Pest control and monitoring five year budget: Option one. ............................. 25
Appendix 1.2. Pest control and monitoring five year budget: Option two............................... 26
Appendix 1.3. Pest control and monitoring five year budget: Option three. ........................... 27
Appendix 2: Five year timelines for options one, two and three. ................................................... 28
A878686 21. Background and Summary
Waingake/Waterworks Bush is an 1100ha area of native forest in the Gisborne Region, owned
and managed by Gisborne District Council (Council) as both a nature reserve and a water
supply catchment.
The significant value of Waingake both for its biodiversity and as a water catchment has been
addressed in detail by Wildlands (Rate et al, 2006) and therefore will not be covered in great
detail here, except to highlight that the site is of regional and national biodiversity significance.
Similarly, the report conducted by Landcare Research (Latham et al, Appendix 3) adequately
addresses the pest animal issues that are compromising the future of the site both as a high
biodiversity site and a water supply catchment. The report details the issue these animals present,
explores options for monitoring and control, and makes recommendations for management. A
summary of these options and recommendations can be found below. In addition, the
Waingake camera survey report (Salmond, 2018, Appendix 4)) gives detail of the findings of the
survey and what the results tell us about the expected densities of animal pests at Waingake.
The purpose of this report is to provide a detailed pest monitoring and control implementation
plan based on the recommendations of the Landcare report.
The implementation plan includes:
1. Three control options for each species including spatial design, timing and method of
control. Option one, aerial pre baiting and control of pest animals using Sodium
fleuroacetate (1080) is the option recommended by Landcare.
2. An operational monitoring plan to monitor relative populations and numbers of pests
using baited chew cards, trap catches, and goat catch per unit effort.
3. An outcome monitoring plan to determine how native populations have responded to
pest control, and if the management objectives have been achieved. This plan
recommends bird counts, permanent vegetation plots and use of automatic bat
detectors.
Approximate costings are provided for each of these aspects of the plan. Table 1.1. below
summarises current densities and expected outcomes from pest control for each of the four
target pest species.
A878686 3Table 1.1. The impacts on Waingake of the four target pest animal species, estimated densities, and expected outcomes from control.
Pest Impacts Estimated current Expected Expected density Expected biodiversity
animal density in Waingake density with with sustained outcomes
Species sustained 1080 control (mix of
toxin and trap)
Possum - Defoliate and kill entire trees at a time. High2. Establishing animal pest management goals
and objectives for Waingake
The establishment of measurable goals and objectives is necessary for any project to determine
if the current management is effective. Goals and objectives should be realistic, achievable
and have a time limit. Outcomes are linked to the overall goal/s and objectives. They should
also be measureable and incorporated into the monitoring programme. Recommended goal/s
for Waingake are;
1. To protect and increase indigenous biodiversity in Waingake/Waterworks bush
2. To maintain/increase the quality of the catchments’ water supply
The three recommended objectives to achieve these goals are:
1. Control animals pests to low densities (specified below).
2. Maintain sustained control of these animal pests.
3. Where possible, expand sustained control to surrounding landscape.
If the programme is successful in implementing our objectives the expected outcomes are:
1. An increase in native fauna.
2. An increase in diversity and cover of indigenous flora, particularly palatable species.
3. An increase in water quality within the catchment.
Section 4 discusses how each of these outcomes can be incorporated in to the monitoring
programme. Achievement of these outcomes will indicate whether the objectives, and the
methods applied to achieve them, need to be modified.
A878686 53. Pest control and monitoring at Waingake 3.1. Background Ship rats (Rattus rattus), stoats (Mustela erminea) and possums (Trichosurus vulpecula) are the most significant predators of native species in the mainland forests of New Zealand (Brown et al, 2015). Cats (Felis catus) and ferrets (Mustela putorius furo) are also important predators that threaten native species, but to a lesser degree. Introduced pest herbivores such as feral goats (Capra hircus), deer and feral pigs (Sus scrofa) and the omnivorous possum also have negative impacts on native vegetation and ecosystems, which can subsequently affect habitat quality for native fauna. In the absence of sustained control of pest animals in Waingake, it is likely that all of the above pest species are present. Populations of native birds, bats, lizards and other fauna are likely to be limited by predation and habitat modification from these pests. In December 2017, a camera trap survey was implemented for the first time at Waingake; 66 camera traps were deployed across the 1100ha over 14 nights, capturing 30,000 images of 11 different animal species (Salmond, 2018). It found that the four primary pests present in Waingake are the brushtail possum, ship rat, feral goat and stoat, all of whose negative impacts have been well documented. Possums and rats are both present in high numbers, goats in moderate numbers and stoats present but not well detected due to the survey design. Feral cats were also a target species for the survey and present in moderate numbers as expected. Additional evidence of the presence of pests in Waingake has been detailed in previous reports (Rate et al and Salmond). This includes; the absence of understorey, most notably plant species palatable to herbivorous mammals, droppings, rubbing and rooting. Bird numbers are low, although most of the common species are present and no lizards have been recorded. Long- tailed bats have been recorded in a single survey carried out by DoC in 2016. Combined, this evidence supports the need for immediate and sustained pest control in Waingake if the collapse of the forest ecosystem is to be halted and biodiversity values recovered. 3.1.1. Change in pest control focus Past pest control operations have focussed on the knock down or removal of a particular pest animal, often for the recovery of a particular species, and using a particular method. The current focus of pest management for biodiversity protection is shifting from mainly single- species control to control of key pest threats at high-value conservation sites and a focus on landscape scale (e.g. catchment scale), multi species control for multiple outcomes. This technique often results in pest control programmes where multiple pest species can be reduced at the same time. Focus should be on ship rats, stoats and possums because these three species currently pose the greatest threat to our native wildlife in mainland forests (Innes et al. 2010). They are known to have caused the extinction of native animal species, currently suppress native animal populations, and will cause further extinctions if not controlled. The goal for Waingake is to recover biodiversity values in general, including a range of indigenous plants and animals. Therefore, a multispecies pest control programme, with the aim to expand to a landscape scale operation, is the most appropriate. Multi species control can also address the issue of predator-prey interactions. A878686 6
Often the successful control of one particular predator species may occur, but without an understanding of how other predator species respond to this control, operations may not protect conservation values. Since many mammalian pests kill other, smaller, mammalian pests, the removal of one species may lead to prey switching. Murphy et al. (1998) showed through diet analysis that following ship rat control operations, stoats switch from rodents to birds. Consequently, when ship rats are controlled (at relatively small sites), stoat control needs to be carried out over larger areas to reduce the predation of birds by reinvading stoats. The removal of a particular pest species may also lead to a reduction in the level of predation or competition experienced by other pest species, causing their numbers to increase. I. Flux and C. Gillies, DOC (unpubl. data) found that ship rats are more abundant at some sites where stoats are controlled than at sites where they are not; Ruscoe et al. (2011) and Sweetapple & Nugent (2007) found that the number of rats increased following the removal of possums, probably due to greater food availability. These effects need to be considered when developing control options for Waingake to avoid negative outcomes of pest control. 3.1.2. Beech mast seeding Large areas of Waingake are dominated by mixed beech forest which will experience mast seeding events in certain years. Long term research in beech forest in the Eglington Valley in the south Island not only verified the relationship between mast seeding and the risk of predation (O’Donnell & Phillipson 1996), but also identified that both ship rat and stoat irruptions have a devastating impact on forest birds (Brown et al 2015). There is no information on how mast seeding in beech forest in Waingake will effect bird populations, however it can be assumed that negative impacts are likely. Additional monitoring and control options should be implemented should a mast seeding occur. 3.2. Landcare Research Report Landcare Research (Landcare) was engaged by Council to develop a pest control and monitoring plan for Waingake with the objective of developing a plan for managing brushtail possums, ship rats, stoats and feral goats in Waingake Waterworks Bush. The report was completed in 2017 and includes: methods for monitoring trends in the populations of these pest mammals suitable methods (tactics) for controlling them methods for monitoring the outcomes of pest control spatial maps showing example networks for monitoring locations and control sites. Below is a summary of the report recommendations. The full report including maps and references can be found in Appendix 3. 3.2.1. Landcare report Summary 3.2.1.1. Management type The goal of managing pest mammals in Waingake is to protect indigenous biodiversity. There are four possible strategies for managing mammal pests in Waingake (prevention, elimination, sustained control and do nothing). Sustained control is recommended as the best option for managing possums, ship rats, stoats and feral goats, and their unwanted impacts. A878686 7
Pest densities in Waingake should be kept at low levels (i.e. comparable to 5% trap catch for
possums and 5% tracking rate for ship rats, and c. 0.2–0.5 goats per square kilometer).
Appropriate levels for stoats are unknown, but trapping should attempt to maintain them at low
numbers.
To ensure that pest control is sufficient to achieve the defined outcomes an adaptive
management approach to monitoring and control in Waingake should be adopted. Collecting
data about the pest population being controlled and the response of the asset to that control,
allows the control method/intensity to be modified to ensure that the desired response to control
is being achieved.
3.2.1.2. Methods for Monitoring pest mammals
A combination of the following four methods may be suitable for long-term monitoring of pest
mammals in Waingake:
camera traps for annual trends and population indices (before versus after control) for
all four species of pest mammals
chewcards for possums and rats (With the desired result beingIn addition to ground-shooting, it is possible that some combination of aerial shooting from a
helicopter, use of thermal imaging equipment, and Judas individuals may be suitable in
Waingake, and these may help to reduce the costs of per capita kill rates at low goat densities
3.2.1.4. Outcome monitoring of forest birds and vegetation
Once control of the pest populations has occurred, it is critical that the responses of the
assets be monitored to determine if the management objectives have been achieved.
In Waingake the objective is to increase indigenous species dominance.
The responses of two broad ecosystem components to pest control in Waingake should
be monitored: forest birds and vegetation. Five-minute bird counts and 20 m × 20 m plots
and seedling ratio plots are well-established methods for monitoring forest birds and
vegetation, respectively, and will probably be suitable for monitoring outcomes in
Waingake.
Surveys for bats should be conducted, as pest control may enable any present
populations to increase in numbers.
If monitoring shows that defined outcomes have not been achieved, pest control should
be adjusted adaptively to further reduce the numbers of pests.
3.2.1.5. Recommendations
Camera traps
Pest mammal populations should be monitored using four methods: camera traps,
chewcards, trap catch, and catch-per-unit-effort.
A camera trap monitoring programme will require about 60 cameras in order to be
sensitive to any changes in pest populations following control. Camera traps should be
deployed randomly about 300–500 m apart, using an active survey design. If there are
sufficient cameras, a subset of cameras should be deployed along game trails to target
goats. Cameras should be set to take photos continuously if an animal is detected.
Chew cards
We recommend deploying baited chewcards using standard methodology to determine
how post-control densities of possums and rats, as indexed by cameras, compare to the
recommended 5% trap catch required for an adequate reduction of predation pressure
on native birds and browse pressure on flora.
Trapping
Trapping protocols for stoats and ground-shooting methodology for feral goats should be
standardised to allow trap catch and catch per unit effort to be estimated.
If there is insufficient funding to control all predator pests, we recommend that possums
and ship rats are the priority, with stoats controlled thereafter. Possum and ship rat
populations should be knocked down using a pre-fed aerial 1080 operation conducted
in winter. Bait stations containing cyanide and a first-generation anticoagulant (e.g.
diphacinone) should be used for maintenance control of possums and rats, respectively.
Rat control will probably need to start in late winter–early spring, and monitoring will help
determine the appropriateness of this.
A trapping grid should be established to maintain stoats at low numbers. Centrally
located traps and perimeter traps should be c. 500 m and 250 m apart, respectively.
A878686 9Shooting
Feral goats should be controlled using shooting conducted by ground-based hunters with
indicator dogs. Also, some combination of aerial shooting, thermal infrared imaging and
Judas goats may improve efficacy. If possible, goats should be controlled in a 1 km buffer
around Waingake to prevent reinvasion.
Ongoing monitoring of bird life, bats and vegetation
Five-minute bird counts should be undertaken every two to four years using the same
150–200 count stations.
At least eight to ten permanent 20 m × 20 m plots should be established in tawa–rimu
forest to monitor change in vegetation structure and composition. Measurement of
seedling subplots should be prioritised if all components of the standard method cannot
be measured.
Automatic bat detectors should be used to survey for long-tailed bats.
A878686 104. Pest control and monitoring implementation The Landcare recommendations for pest monitoring and control should be implemented as follows. 4.1. Pest monitoring Generally it can be expected that in absence of any control, pest animals will be present to some degree. However, pest mammal populations differ greatly in composition and dynamics depending on forest type, mast seed events and altitude (Brown et al 2015) and also in response to control and other applied management. Therefore, it is important to understand pest populations at the target site to know where and when to target control efforts. To do this it is essential to monitor relative pest animal numbers using appropriate methods and at key times. 3.1.1. Camera traps Camera traps are a relatively new addition to the pest monitoring tool box in New Zealand and present a relatively cost effective way to monitor multiple species across relatively large areas. Camera trap should be deployed for both monitoring of annual trends and population indices (before versus after control, during beech mast seeding). Timing It is recommended that camera deployment be in early spring (September). It is important that once the time of year is chosen it must be repeated annually to accurately detect population trends. Deployment for monitoring of annual trends should be done in late winter to early spring primarily because that is when birds are starting to nest, and knowing the relative abundance of predators on the landscape at this time of year is useful (Latham pers comm.). Alternatively, if it is necessary to get an idea of the maximum annual relative abundance of predators in Waingake, late summer might be appropriate. Deployment should also be done to gauge population characteristics before and after pest control. This can work in with annual trend monitoring. For example, cameras could be deployed prior to possum control during winter and then set again during spring to gauge the success of the control operation. Camera surveys should also be deployed during a mast beech seed event to detect changes in rat and stoat populations. Methods Camera deployment planning and methods should generally follow that used in Salmond (2018), with the following modifications. Lure Camera trap survey designs can be classed as active or passive. Active designs use bait or a lure to attract target species to the camera, whereas passive designs do not use a lure and rely simply on the target species passing through the camera frame by chance. There are positives and negatives for both designs. Using a passive design is often appropriate for multi-species surveys to avoid any complications that might arise from changing the behaviour (positively or negatively) of one or more species. The negative of the passive design is that it is likely to result in fewer detections for most species (if not all) and this is likely to be most noticeable for species like stoats (D.Latham, pers comm). A878686 11
In contrast, an active design may attract higher numbers of target species. However, there is
then a question of how many of the additional detections capture new individuals versus
increased activity of the same individuals. Other aspects to consider for an active survey are;
- How much statistical confidence can you have in trends resulting from increased activity
because of a lure?
- What type of lure should be used?
- What effect will a lure that targets one species (e.g. rats) have on the other species of
interest in a multi-species design? For example, a lure that attracts rats that then leave a
scent may deter or attract other species, or using a food lure that has changes the
behaviour of possums and rats but not attracted other target species.
The initial camera survey carried out at Waingake was an active design using a flour based food
lure. This attracted rats and possums to camera traps but not mustelids or cats. This prompted
further conversations with Landcare on a more suitable survey design. Their recommendation
was that an active design to be applied but using peanut butter baited chew cards as lure,
placed in front of cameras. This will prompt the animal to pause in front of the camera and
therefore increase the likelihood of capturing an identifiable image. This will attract rats and
possums, and the high activity of rodents at a camera trap may increase stoat captures
(D.Latham pers comm). Although behavioural changes associated with this design will likely raise
the index for rats, possums and maybe stoats, impacts on the results will not be significant, and
as long as the design is replicated each time, the data for comparison will be robust.
Given the difficulty of getting good samples sizes for mustelids as they rarely exist in high numbers
(with some exceptions) the extra effort to design a camera survey to target them particularly is
not warranted. Trap catch is the easiest way to provide an indication of stoat numbers.
The recent camera survey captured 85 separate visits from feral goats. Landcare also
recommend that for future surveys, a subset of camera traps (8-10) target game trails specifically
to capture goats.
Recommended changes to camera trap methodology
1. Use baited (peanut butter) chew cards as lure, placed in front of cameras at each
camera trap.
2. Deploy a subset (eight to ten) of cameras un-baited on known game trails to increase
the chance of capturing feral goats. These same camera locations should be used each
time the survey is replicated, similarly to the baited locations.
3. Protocol should be developed for camera set up at each site to ensure that all sites are
consistent. Protocol should ensure consistency in;
- Camera height from the ground
- Degree of camera angle
- Field of view
- Distance to target
- Placement of lure
(For more detail on camera set-up issues refer to Salmond, 2018)
A878686 12Costs
Equipment costs for camera trap monitoring are relatively low as the camera’s themselves and
the memory cards have already been purchased. Additional equipment and estimated annual
costs are below.
The highest expenditure for future camera surveys will be in staff time required for field work
(deployment and collection of cameras) and analysis of data. Estimated times for each are
shown below.
Item Annual Cost Hours required
Chew cards x 200 ($0.35e) $70-$100.00
Field sundries (Tape, stationary, nails, $3500.000
batteries etc)
Field time 190
Data analysis 100
Totals $3600.00 290
3.1.2. Baited chew cards
Peanut butter baited chew cards should be used to determine possum and rat densities with the
aim of achieving and sustaining a3.1.4. Catch rate for goats
The effectiveness of goat control in Waingake involves using two methods. The first method is
based on how many goats are killed in the block. The goat kills per hunter man day are
calculated (catch-per-unit-effort). The aim is to reduce goat kill numbers down to less than one
per hunter man day.
The second method involves monitoring the vegetation in Waingake; 12 seedling lines have been
established at the site to show the impact of browsers on preferred native shrubs which occur in
the forest. Palatable species are vulnerable to browsing by goats and deer in a specific height
range (30 cm – 135 cm). The heights and tallies of palatable species in the shrub tier are recorded
in plots along each of the lines.
Costs
Equipment costs and staff time associated with catch per until effort are largely included in the
control budget with the exception of time required for data analysis.
For vegetation monitoring, equipment costs are low and include the usual field sundries.
Approximately two vegetation lines can be measured per day totalling six days of field work for
two people plus data analysis.
DoC is currently carrying out goat control in Waingake. Funding from a DOC community fund
bid awarded to Ngai Tamanuhiri is being used to carry out vegetation monitoring. It is possible
that future monitoring could combine vegetation monitoring for goats with 20x20 plots.
Estimated costs for current goat control and monitoring are shown below.
Item Annual Cost Hours required
Field sundries for vegetation $200.00
monitoring (stationary etc)
Field time 80
Data analysis 16
Total $650.00 96
4.2. Pest control
The main factors influencing the choice of mammal control techniques are;
- The target species,
- the desired residual abundance,
- scale of the project,
- cost,
- Land topography,
- available expertise,
- community acceptance of the proposed actions.
Considering all of these, and the recommendations from Landcare, there are three control
options proposed. These options provide varied approaches to pest control at Waingake, having
attempted to incorporate options that require different levels of funding, a range of
methodologies, and address what is likely to be a range of stakeholder preferences.
An alternative strategy might be to combine methods from across the different options to
achieve the same outcome. For example, trapping of possums and stoats may be combined
with the use of toxins for rats. Or a trapping programme may use a range of trap types, beginning
with single kill traps for rats and replacing them with self-resetting traps as resources allow.
A878686 14A robust monitoring programme should be in place to assess the efficacy of any control methods
which can then be adjusted as required as per the adaptive management approach.
4.2.1. Option one (preferred option proposed by Landcare).
Initial knockdown of possums and rats (and most likely mustelids and cats due to secondary
poisoning) using biodegradable sodium fluoroacetate (1080) toxin. This would be followed by
subsequent years of maintenance control using trapping and alternative toxin. Repeat 1080
knockdowns would occur every four to five years depending on monitoring results.
There have been significant developments in the last 15 years in toxins for targeting ship rats,
possums and stoats. This includes the use of GPS tracking for aerial operations to ensure accuracy
of deployment, and the reduction of the amount of toxin required for an initial knockdown, which
has gone from 20kg of 1080 cereal bait/ha in the 1980’s to 1-2kg/ha more recently.
1080 in particular has become the preferred option for multi species pest control. This is because
it breaks down quickly in water and on land unlike anticoagulants (e.g. brodifacoum) which
persist in the environment and in live animal tissue. It also provides the benefit of secondary
poisoning to additional pests such as mustelids and feral cats who scavenge carcasses of
poisoned animals, and is relatively humane compared to most other toxins (PCE report, 2011).
When compared to other methods of animal pest control which may be effective in particular
situations, the only practical and cost-effective option that is available for controlling possums,
rats and stoats in large and inaccessible areas is the aerially delivery of 1080 poison. (PCE report,
2011).
The main phases of Option one are;
Active treatment
1. Aerial pre-feed of non-toxic cereal bait – pre feeding has been shown to increase bait
take during toxin application, therefore a pre-feed of non-toxic bait is recommended.
This should occur in winter at least two weeks prior to toxin deployment.
2. Aerial or ground application of the toxin itself. This should occur in winter following
application of pre-feed. Ground application may be more acceptable. Costs are similar
for aerial and ground application if carried out by an independent contractor. Ground
application is likely to be cheaper if carried out in-house, but will have a high staff/time
requirement. To maintain pest animals at low levels, a 1080 knockdown should occur
every 3-5 years but this will depend on monitoring results.
3. Concurrent trapping of stoats is recommended as secondary poisoning may not reduce
stoats to the desired levels. Traps should be DOC200’s located as recommended by
Landcare with traps placed internally at 500m spacing’s and at 250m spacing’s around
the perimeter of the site. Dried meat bait such as Erayz is recommended for stoat traps.
Maintenance control methods
4. For interim years, maintenance control of possums and rats should take place using
alternative toxins. This can be done with bait stations at relatively low densities because
the initial knockdown will have reduced pest numbers significantly and re-invasion to pre-
control densities will take some time.
5. Rats should be controlled in Year two and three as re-invasion to pre-control densities
may occur as early as six months after control.
A878686 15Philproof bait stations (large) should be spaced at 100m x 100m (1100 units’ total) and
filled with Diphacinone toxin. These should be activated in late winter early spring.
6. Stoat trapping should be continued but at increased densities (300m spacing internally
and 125m spacing along the perimeter).
7. Year four (or earlier, depending on monitoring results) should see the addition of
maintenance control of possums. This should occur in winter using the existing bait station
network laid for rats, but with a cyanide based toxin such as Ferratox.
8. Rats can subsequently be controlled in spring.
9. Stoat trapping should continue as above.
10. The next 1080 knockdown should occur in year five.
11. Ground based shooting conducted by professional hunters (preferably with indicator
dogs) is recommended for goat control. Shooting should take place four times a year for
approximately 50 hours each time. If Resources allow, control should be extended to
include a control buffer of c. 1km around Waingake to prevent constant re-invasion. Also,
some combination of aerial shooting, thermal infrared imaging and Judas goats may
improve efficacy
Estimated five year budget:
$136,985.00 - $244,985.00 + 1.5 FTE
A detailed summary of the approximate budget for option one can be found in Appendix 1.1.
with timing of operations in Appendix 2. Both the costing and timeline are for the first five years
although. It is intended that animal pest control will continue at some level indefinitely, the nature
of which will depend on monitoring results and resources.
Staff resources: Initially high, then low
Staff resource requirements for this option will vary greatly depending on the method of toxin
delivery, be it aerial or ground application, and the possible engagement of an independent
agency to carry out the operation. For a cost, agencies will carry out all aspects of the operation
from the application of the pre-feed and toxin, to the planning, consent application and
supporting the consultation process. This reduces in-house staff costs considerably. Time
requirement increase depending on what aspects of the operation are carried out in-house,
however this then reduces expenditure.
Staff requirements are reduced in year two, due to the nature of the control methods and are
largely a result of field time to deploy bait stations and traps. The use of an initial knockdown
using 1080 means that only low levels of maintenance control are needed. Staff requirements
will then increase slightly in year four or five for the next 1080 operation, although much
infrastructure and planning will already be in place.
Biodiversity outcomes for Option one: Med-high
- Noticeable recovery of indigenous fauna, e.g. the majority of existing forest birds show
an increase in numbers, new species may colonise the area
- Noticeable recovery of indigenous flora e.g. palatable plant species become more
common, the density and diversity of indigenous plant species increases.
- Less noticeable recovery across other taxonomic groups (bats, lizards, frogs). This will be
determined by additional monitoring.
A878686 16- Improved water quality as a result of a decrease in faecal contaminants from browsing
mammals and better sediment retention due to increased plant cover.
4.2.2. Option two
Although the application of 1080 (either aerial or ground based) is by far the most effective and
efficient way to manage multiple pest species over a large area, its use at Waingake may not
be acceptable given its perceived negative associations.
Option two proposes seasonal control of possums and rats using alternative toxins. Seasonal
control allows a more resource friendly option of rat and possum control during late winter, early
spring prior to bird nesting. This does mean that an increase in these pests is likely late summer,
which may have impacts on biodiversity. Year round application of poison would be more
effective at maintaining continuous low levels of pests, however this would increase costs
considerably.
The main phases of Option two are:
Active treatment
1. Establish bait lines with Philproof bait stations (large) at 75m x 75m intervals (1955 units
total). As there has been no initial knockdown of pest animals, bait stations must be
densely placed to achieve the desired reduction in pests.
2. Bait for rat control first. Unlike a 1080 operation, rats can interfere with other possum bait
by eating the cereal capsule surrounding the toxin Rat control should use a Diphacinone
based bait such as D-block. Baiting should occur in winter with a second application in
spring after possum control and prior to bird nesting.
3. Control possums using the already established network of bait stations. Bait should be
cyanide based such as Ferratox. Baiting should occur in late winter following rat control.
4. Stoats are controlled as above using baited DOC 200 traps the higher density spacing
(300m spacing internally and 125m spacing along the perimeter).
Maintenance control methods
5. Years two-five continue the above baiting/trapping programme. Budget decreases
significantly as the only outgoing costs are for toxin replacement. However staff resources
remain relatively high.
6. Ground based shooting conducted by professional hunters (preferably with indicator
dogs) is recommended for goat control. Shooting should take place four times a year for
approximately 50 hours each time. If Resources allow, control should be extended to
include a control buffer of c. 1km around Waingake to prevent constant re-invasion. Also,
some combination of aerial shooting, thermal infrared imaging and Judas goats may
improve efficacy
Estimated five year budget:
$151,017.30 + 1.85 FTE
A detailed summary of the approximate budget for option two can be found in Appendix 1.2.
with timing of operations in Appendix 2. Both the costing and timeline are for the first five years
although. It is intended that animal pest control will continue at some level indefinitely, the nature
of which will depend on monitoring results and resources
A878686 17Staff resource requirements: Initially high then moderate
Staff resource requirements are slightly higher for year one as a result of the level of planning
required for a bait station network and then deployment of bait stations.
In subsequent years staff requirements remain moderate compared to option one due to the
higher number of bait stations required and the frequency of baiting.
As toxins are developed and refined it may be possible to control possums and rats
simultaneously, reducing the need for multiple baiting.
Biodiversity outcomes for Option two – Moderate
- Recovery of indigenous fauna, e.g. some existing forest birds shows an increase in
numbers.
- Noticeable recovery of indigenous flora e.g. palatable plant species become more
common, the density and diversity of indigenous plant species increases.
- Less noticeable recovery of bird species and other taxonomic groups (bats, lizards, frogs)
that rely on sustained possum and rat control. This will be determined by additional
monitoring.
- Improved water quality as a result of a decrease in faecal contaminants from browsing
mammals and better sediment retention due to increased plant cover.
4.2.3. Option three
Trapping is still the major tool for large-scale stoat control, is widely used to target possums in
conjunction with toxins, but is rarely used as a main tool for ship rat control. Controlling ship rats
with single-kill traps is generally ineffective at large scales because traps need to be closely
spaced and regularly checked and trapping is therefore expensive.
This option has been proposed because the use of toxins at Waingake may not be acceptable
by all stakeholders or, it may be appropriate to use trapping in conjunction with toxins. Although
this is not presented as an option, it would not be difficult to integrate control methods from each
of the above options.
Year one is the most resource intensive for multispecies trapping operations, due to the cost of
the initial set up of trap lines and purchase of traps. Subsequent years see only the cost of the
bait or lure. However the staff hours remain high due to the need for the regular checking and
rebaiting of traps.
The main phases of Option three are:
Active treatment
1. Establish trap lines for possums at 100m x100m intervals (1100 units total) using baited
possum sentinel traps.
2. Traps should be active from June to October.
3. Establish trap lines for rats and stoats at 75m x 75m intervals (1955 units total). Slightly wider
spacing of 100m x 75m has been used will still be effective but may not reduce rats to
desired levels. Regular monitoring will inform this. Traps should be DOC200’s baited with
a rabbit meat lure for stoats and a suitable rat lure.
4. Traps should remain active from June to October. A subset of traps should remain active
for stoat trapping year round.
A878686 185. An alternative trap for the control of rats and stoats is the Goodnature self-resetting trap.
This trap uses a long life lure and resets after each kill, so only needs checking every four
to six months*. The units are more expensive so initial costs are high and gas canister and
bait refills are required annually.
However they do considerable reduce staff hours normally required for regular checking
and re-setting of traps. If used, Goodnature traps should be deployed at 75m x 75m
ideally, although 100m x 75m is acceptable but with lower success rates (again,
monitoring will inform this). They should be set continuously.
Maintenance control methods
6. Ground based shooting conducted by professional hunters (preferably with indicator
dogs) is recommended for goat control. Shooting should take place four times a year for
approximately 50 hours each time. If Resources allow, control should be extended to
include a control buffer of c. 1km around Waingake to prevent constant re-invasion. Also,
some combination of aerial shooting, thermal infrared imaging and Judas goats may
improve efficacy.
Estimated five year budget:
$151,017.30 + 1.85 FTE
A detailed summary of the approximate budget for option three can be found in Appendix 1.3
with timing of operations in Appendix 2. Both the costing and timeline are for the first five years
although. It is intended that animal pest control will continue at some level indefinitely, the
nature of which will depend on monitoring results and resources.
Staff resource requirements: Initially high then moderate-high
Staff requirements for the first year are high to develop and implement a complex trapping
network and deploy a large number of traps. Subsequent years remain relatively high as a large
network of traps requires checking and rebaiting at monthly intervals during the trapping period.
Staff requirements would be significantly reduced with the use of Goodnature self-resetting rat
and stoat traps as these need only be checked at four to six monthly intervals.
Biodiversity outcomes for Option three – Moderate
- Recovery of the indigenous fauna, e.g. some existing forest birds show an increase in
numbers.
- Noticeable recovery of the indigenous flora e.g. palatable plant species become more
common, the density and diversity of indigenous plant species increases.
- Less noticeable recovery of bird species and other taxonomic groups (bats, lizards, frogs)
that rely on sustained possum and rat control (use of Goodnature traps may influence
this). This will be determined by additional monitoring.
- Improved water quality as a result of a decrease in faecal contaminants from browsing
mammals and better sediment retention due to increased plant cover.
4.3. Outcome monitoring
Monitoring of the pest population itself will indicate the effectiveness of control methods. If the
pest population has been reduced to the levels required to achieve the desired outcomes of
the project (Section 2) this should be detectable from outcome monitoring.
A878686 19Outcome monitoring can give an indication of nesting success of particular bird species by comparing detectability to previous seasons before and after pest control, or compare the density of seedlings in one place over time. Project goals for Waingake are: 1. To protect and restore indigenous biodiversity in Waingake/Waterworks bush. 2. To maintain/increase the quality of the catchments’ water supply. This will be done by achieving; 1. An increase in native fauna. 2. An increase in diversity and cover of indigenous flora, particularly palatable species. 3. An increase in water quality within the catchment. Monitoring of forest bird and vegetation ecosystems In order to measure progress towards these goals the monitoring of two broad ecosystem components, forest birds and vegetation, is recommended (Latham et al, 2017). Suitable monitoring methods for these are also well established, allowing for comparison to data from other sites. Monitoring of the existing bat population is also recommended. As the restoration of Waingake progresses, it may become appropriate to introduce additional monitoring to assess other taxa such as herpetofauna and invertebrates. Expected rate of recovery for flora and fauna It is important to note that the rate of recovery of indigenous forest species after animal pest control can vary greatly depending on the forest type, historical land use and any previous pest management. Waingake has been occupied by a range of herbivorous and carnivorous pest animals for many years, resulting in a significant decline in the health of the forest, which if continued, will result in complete collapse. While some of the more common forest birds such as fantail, bellbird and tomtit, may show increases within the first two years following pest control, plant species and other animal taxa are likely to take longer. The removal of browsing mammals, particularly goats and possums, could see the recovery of palatable species like hangehange (Geniostoma ligustrifolium)and Coprosma sp. within three to five years, but a noticeable recovery in understorey vegetation is likely to take much longer, up to ten years. Changes in bat populations may take up to 15 years to detect. This needs to be considered when allocating timelines to goals and objectives so that these are realistic and achievable, and that stakeholder expectations can be managed. 4.3.1. Bird count Five minute bird counts have been used extensively in New Zealand to monitor changes in bird abundance, providing indices on relative bird abundance over time. This method should be used at Waingake to monitor changes in the avian community following pest mammal control. Latham et al (2017) recommend 150-200 count stations be established at Waingake to accurately detect changes in forest bird abundances. These “stations could be along existing tracks e.g. bait or trap lines but cover the range of habitats and altitudes over Waingake. Counts should take place in November- December and be repeated every two years using the same locations each time. Counts could be spread across two years i.e. half the counts carried out in year one, the other half in year two and then the first half repeated in year three, and so on. A878686 20
For data to be statistically robust, bird counts should be carried out by experts and where possible, be repeated by the same person each time. For more detail on the five minute bird count method and analysis of data see Spurr and Powlesland (2000). Electronic bird recorders that can be left in the field and pre-set to record birds are also becoming more popular. These could be investigated. Bird monitoring costs Equipment costs will be relatively low and include field sundries such as recording sheets, compass, GPS, binoculars etc. The main expenditure for bird counts will be the staff time required for field work and analysis of data. Estimated times for each are shown below. Item Annual Cost Hours required Field sundries $300.000 Field time 50 Data analysis 10 Totals $300.000 60 4.3.2. Vegetation plots Permanently marked 20x20 plots have been widely used in New Zealand forests to monitor changes in vegetation composition and structure. This method involves establishing a plot 20m x 20m at a predetermined location, measuring the diameter of small trees and saplings, the height of seedlings, and doing a broad description of the vegetation structure and composition. Latham et al (2000) recommend establishing eight to ten plots at random, pre-determined locations throughout Waingake. This should be carried out during spring/early summer when most indigenous species are in flower, therefore November-December have been suggested. Plots should be repeated every five years, however they can also be carried out across years if time does not allow for all ten to be done at once, i.e. three plots could be done in year one, three in year two and four in year three, then the sequence repeated beginning in year five. Detailed methods, equipment and data analysis for 20 x 20 plots can be found in McNutt, 2012. A monitoring method not covered in Landcare recommendations are the use of photo-points. These are a quick and easy method of monitoring change in vegetation over time, particularly in disturbed sights, and are a good method of interpreting change for the non-technical community. These could be considered as part of the vegetation monitoring programme. Vegetation monitoring costs Costs for establishing 20 x 20 plots include permanent plot markets (usually yellow numbered cow tags on small metal stakes) and additional field gear such as measuring tapes and stationary. Staff time required to do field work is around eight to ten hours per plot with four people including travel (approx. 40hrs/plot). Data analysis will require more time than bird counts as there are several data sets to analyse. Estimated times and costs are shown below. Item Annual Cost Hours required Field equipment (total for 10 plots) $3000.000 Field time 400 Data analysis 40 Totals $3000.00 440 A878686 21
4.3.3. Bat monitoring Long-tailed bats have been recorded at Waingake. It is recommended that bats be monitored to assess any changes in the population in response to pest control. Latham et al (2017) recommend deploying automatic bat detectors to survey for bats which provides an index of bat activity over time. Bat monitoring should take place in summer. Bat detectors should be placed at randomly selected points approximately 1km apart in likely foraging paths. They should be at least 200m away from the forest edge. If possible, detectors should be set to record from sunset to sunrise for several consecutive nights. Monitoring should be done during fine weather where night time temperature is at least 10deg C. Locations, time and methods should be repeated annually. For more detail on methods and data analysis see DoC, (2007). There is little data available on standard analysis of bat detection data, but the number of and regularity of bat detection should be compared across years. Bat monitoring costs The bat detectors used for initial surveys at Waingake were the property of DoC Gisborne. The continued use of these detectors is possible, and would remove the need for Council to purchase this equipment. Field time required for bat monitoring is minimal and only requires a staff to set up the detectors in the field and then collect them in. Estimated times and costs are shown below. Item Annual Cost Hours required Field equipment Nil if DoC units available Field time 20 Data analysis 40 Totals $0.00 60 A878686 22
References Brown K, Elliott G, Innes J, Kemp J, (2015) Ship rat, stoat and possum control on mainland New Zealand: an overview of techniques, successes and challenges. Department of Conservation, Wellington. 36 p. Evaluating the use of 1080: Predators, poisons and silent forests. (2011) Parliamentary Commissioner for the Environment report. Innes J, Kelly D, Overton J.McC, Gillies C, (2010) Predation and other factors currently limiting New Zealand forest birds. New Zealand Journal of Ecology 34: 86–114 Latham ADM, Fitzgerald N, Warbuton B (2017) Animal pest monitoring and control methods for Waingake bush. Landcare Research Envirolink Report 1780-GSDC145 for Gisborne District Council Murphy E.C. Clapperton, B.K. Bradfield P.M.F. Speed H.J. (1998) Effects of rat-poisoning operations on abundance and diet of mustelids in New Zealand podocarp forests. New Zealand Journal of Zoology 25: 315–328. McNutt. K. (2012) Permanent 20x20 forest plots. Version 1.0. In Greene. T, McNutt. K (editors) 2012. Biodiversity Inventory and Monitoring Toolbox. Department of Conservation, Wellington, New Zealand O’Donnell C.F.J. Phillipson S.M. (1996) Predicting the occurrence of mohua populations from seedfall, mouse and predator fluctuations in beech forests. New Zealand Journal of Zoology 23: 279–286. Rate S and Gillies R (2006) Waingake Waterworks Bush: An outstanding opportunity for ecological restoration. Wildlands LTD. Prepared for Department of Conservation, Gisborne. Ruscoe W.A. Ramsey D.S.L. Pech R.P. Sweetapple P.J. Yockney I. Barron M.C. Perry M. Nugent G. Carran R. Warne R. Brausch C. Duncan R. (2011) Unexpected consequences of control: competitive versus predator release in a four-species assemblage of invasive mammals. Ecology Letters 14: 1035–1042. Salmond A. (2018) Waingake Camera deployment: project planning, methodology and recommendations. Report prepared for Gisborne District Council. Spurr E. B. and Powlesland R. G. (2000) Monitoring the impacts of vertebrate pest control operations in non-target wildlife species. Department of Conservation Technical Series 24. Department of Conservation, Wellington. Sweetapple P.J. Nugent G. (2007) Ship rat demography and diet following possum control in a mixed podocarphardwood forest. New Zealand Journal of Ecology 31: 186–201. Sedgeley J. (2012) Bats: counting away from roosts— automatic bat detectors. Version 1.0. Biodiversity Inventory and Monitoring Toolbox. Department of Conservation, Wellington, New Zealand A878686 23
Appendix 1. Pest control and monitoring five year budget A878686 24
Appendix 1.1. Pest control and monitoring five year budget: Option one.
1. Aerial pre-bait followed by aerial or ground application of 1080 toxin.
2. Goat Control
3. Trapping of stoats
4. Maintenance control of rats and possums between 100 operations (yr1 and 4/5)
Year
One Two Three Four Five
Goats $9,000.00 $9,000.00 $9,000.00 $9,000.00 $9,000.00
Possums $15,000.00 - $88,000.00 $3300.00 (toxin) $15,000.00 - $50,000.00
Rats (1080) $19,225.00 Bait stations $580.00 (toxin) (1080) $580.00 (toxin)
+ toxin)
Stoats $8,750.00 $350.00 (lure) $350.00 (lure) $350.00 (lure) $350.00 (lure)
Sub Total $32,750 - $105,750.00 $28,575.00 $13,230.00 $24,350.00 - $59,350.00 $9,930.00
Monitoring $8150.00 (equipment) + $5000.00 (equipment) + $5000.00 (equipment) + $5000.00 (equipment) + $5000.00 (equipment)
0.75 FTE (Approx 100 field 0.75 FTE (Approx 100 0.75 FTE (Approx 100 field 0.75 FTE (Approx 100 field + 0.75 FTE (Approx 100
days plus project field days plus project days plus project days plus project field days plus project
management and data management and management and data management and data management and
analysis) data analysis) analysis) analysis) data analysis)
Total ($) $40,900.00 - $113,900.00 $33,575.00 $18,230.00 $29,350.00 - $64,350.00 $14,930.00
Total (Time/staff) 2 X FTE (project 1.25 x FTE including 1.25 x FTE including 1.75 X FTE (project 1.25 x FTE including
management plus support from in house support from in house management plus support from in house
support from in house Biosecurity Team. Biosecurity Team. support from in house Biosecurity Team.
Biosecurity Team) Biosecurity Team).
A878686 25Appendix 1.2. Pest control and monitoring five year budget: Option two.
1. Seasonal control of possums and rats using alternative toxin
2. Goat control
3. Trapping of stoats
Year
one two three Four Five
Goats $9,000.00 $9,000.00 $9,000.00 $9,000.00 $9,000.00
Possums $4,950.00 $4,950.00 $4,950.00 $4,950.00 $4,950.00
Rats $34,007.25 $870.00 $870.00 $870.00 $870.00
Stoats $24,750.00 $700.00 $700.00 $700.00 $700.00
Sub -Total $72,707.25 $15,520.00 $15,520.00 $15,520.00 $15,520.00
Monitoring $8150.00 (equipment) + $5000.00 (equipment) + $5000.00 (equipment) + $5000.00 (equipment) + $5000.00 (equipment) +
0.75 FTE (Approx 100 field 0.75 FTE (Approx 100 0.75 FTE (Approx 100 0.75 FTE (Approx 100 0.75 FTE (Approx 100
days plus project field days plus project field days plus project field days plus project field days plus project
management and data management and management and data management and data management and
analysis) data analysis) analysis) analysis) data analysis)
Total ($) $80,857.30 $20,520.00 $16,520.00 $16,520.00 $16,520.00
Total (Time/staff) 2.25 X FTE (project 1.75 x FTE including 1.75 x FTE including 1.75 x FTE including 1.75 x FTE including
management plus support from in house support from in house support from in house support from in house
support from in house Biosecurity Team. Biosecurity Team. Biosecurity Team. Biosecurity Team.
Biosecurity Team)
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