Chew Card Draft Protocol

Chew Cards Protocol for Landcare Groups for Annual Pest Free NZ Monitoring Draft Guidelines Prepared by Andrew Sinclair, Whakaupoko Landcare. andrew@climbingjack.com,
Ph 09 2363 647
Introduction
Mainland Pest Free New Zealand is an admirable goal. Here is a good solution for our 2 worst pests, (rats & possums), to combine with your ongoing pest control programme. It includes an intensive, low cost monitor with Chew Cards combined with immediate follow up targeted pest control where required. It suits a cooperative approach where landowners combine forces and work together. This simple process is a great way to achieve very low levels of pests. It provides excellent pest monitoring information on a regular basis and gives excellent feedback to all participating in the programme combined with clear annual goals. Most importantly it allows people to learn more about pest control and to become better skilled in how to improve pest control to really make a difference.
With use of this programme and it being adopted by an increasing number of landowners on an annual basis, possums should be able to be contained at extremely low numbers if not eliminated completely. This would then leave the main focus for the rest of the year to be just targeted on rats and any other selected pests.
Background
Chew Cards are very sensitive to the presence of pests. For possums for instance they are approximately 7 times more sensitive than Residual Trap Catch techniques. They are low cost, easy to use, easy to interpret results and have the advantage of identifying the presence of a range of pests including rats & possums. Where pest numbers are low they can play an excellent role in your control programme and with providing monitoring data towards achieving a pest free status.
Landowners are encouraged to work together with the same approach to monitoring and Control Pests. This way the Pest Free Area can grow and be less vulnerable to reinvasion from outside properties.
Pest Free NZ Status can be used in just individual household properties. Ideally this grows to incorporate clusters of landowners working together to a common goal.
Total Coverage Option. (This is as used by Animal Health Board for pest presence / absence and is designed to cover all areas where pest will likely be).
  • In areas of bush or scrub, locate Chew Cards at 50m spacings and consider less if rats are the main target. Locate where pests are most likely to be.  For blocks of bush more than 200m wide more run transects no further than 150m from each other.
  • Around the perimeter of the Pest Free Zone if it is solid bush then use a 25m spacing.
  • Along shelter lines use a spacing of 100m
  • In scattered bush ensure no bush is more than 100m away from a Chew Card
  • Locate Chew Cards close to all houses, sheds and any other rural  buildings as this is where rats especially will seek cover
Labelling & Location
  • Choose a good site rather than stick exactly to 50m
  • Label Chew Cards with an individual
number.
  • Take a gps coordinate of the location for mapping
purposes
  • Attach to trees / fences etc, approx 30cm
above ground level using a 50 – 75mm flat head nail.
Fold in half and leave the top flap at approx. 45⁰
  • Avoid locating on fence lines in areas where pests are exposed to electric fencing.
Some pests have learned behaviour and avoid fences including non electric.
Leave the Chew Cards out for a period of 7 – 8 days
Processing Results
Create a map of the area monitored and ideally show the location of all the chew cards along with their results. Where there are any positive rat and / or possum results, target these areas for pest control. Ideally begin active pest control within 2 days of a positive result. Chew Cards have the bonus of acting the same way as pre feeding for a period of 9 – 11 days after the Chew Cards are first put out. Pests keep coming back each night. You choose the method of pest control and note that if rats are hungry they may have destroyed any evidence of the presence of other pests including possums.
Draft Pest Free Status
For this standard monitoring the focus is on rats and possums. Because this protocol is developed primarily for mainland use, the status level is for a moment in time as there is always the risk of reinvasion. Here is a draft of a suggested range of annual status levels. It needs more thought but the concept is to provide measureable, annual feedback and to perhaps also reflect and acknowledge an achievement of a defined minimum standard.

Pest Free Status

% Rats

% Possums

% Carnivores *

% Mice

Level 1

First time results
0

0

?

?

Level 2

First monitor results

? (above 0)

? (above 0)

Results after follow up pest control

0

0

Level 3

First monitor results
? (above 0)

? (above 0)

Results after follow up pest control

? (above 0)

? (above 0)

* Carnivores can be either cats, mustelids or hedgehogs. You can record these separately if you have the skills to read the bite marks for different carnivores.
Monitoring Frequency and Timing
The most logical use for pest free NZ Status is on an annual basis. The time of year ideally coincides with when pests are hungry. This makes the Chew Cards more sensitive and makes it easier to achieve good follow up pest control success where required.
A good time is August as food supplies are typically low in most parts of New Zealand. Towards the end of a drought can be very good but this is generally more variable from year to year in most environments in NZ.
If Chew Cards are primarily being used to monitor rats, then you may consider monitoring more than once per year given rat breeding capabilities.
Interpreting, confirming and recording results
To assist with Chew Card bite mark identification there is growing on line support. Peter Sweetapple and Graeme Nugent from Landcare Research are making available increasingly more detailed images and explanations that are making it a whole lot easier.
Recording The person recovering the CTC in the field should make a permanent note on the CTC of the result grouping as per the table below. Just use the CN code for puncture marks for any carnivore unless you are skilled enough to differentiate C, H, F, S & W. Results should be transferred onto a standard computer record. Eg record via Google Maps.

R = Rat

P = Possum

B = Rat & Poss

N = None

CN = Carnivore

C = Cat

U= Unidentified

R = Rabbit

H = Hedgehog

F = Ferret

S = Stoat

W = Weasel

Livestock Ideally do not allow livestock access to Chew Cards over the 7 days. Where Livestock interference is likely, CTC’s should be placed above reach (eg. 2m above ground level).
Annual Pest Control Programme
This is totally up to the landowner(s) / group to choose. Use what you are comfortable with and what you think produces results. All options re well documented and have their strong and weak points.
For the annual monitor what should you do on sites where rats are present? Where possums are present?
Examples include:
Leg holders
Bait station with eg brodifacaum
Kill traps such as Timms trap / Sentinel trap
DOC 200/250 for rats (& also potentially mustelids)
Kill Traps for rats.
Good Nature kill traps
Because the site is identified as having pests present you can focus on these sites and not be wasting time and energy on sites where there is no pest presence.
Chew Card Sample Monitor Option
For sampling large areas of bush with limited resources Chew Cards can be used as random transect sample lines. (In much the same way as trend monitoring with legholders with assessing possum RTC’s).
  • In bush use 1 card every 50m. Set as a straight line (eg 10 – 20 cards on a transect line). Chew Cards should be attached to the nearest available site at the pre-determined spacing. Additional lines should be no closer than 200m distant from the first.
This option is not part of the Pest Free Status initiative but provides pest information in much the same way as RTC sampling methods. Result interpretation is different due to the greater sensitivity of the Chew Cards (x factor of 7). Also high densities of rats can mask the presence of possums. There may be variations of these 2 options that are adapted to your specific needs. The key is that if the Chew Cards are intended to be used for pest population trend monitoring, then be consistent with your practises.