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2. pest control

Pest Animal Factsheet
possums
Environmentally, possums cause major
damage to native forests by browsing on
trees and regenerating plants. Possums are
also known to eat native birds’ eggs, chicks
and native land snails.
Pest Classification
Possums have “wild animal” status under
the Wild Animal Control Act (1977).
Figure 1 - Possum
Introduction
Originally introduced to New Zealand in
the late 1800s to establish a fur trade, the
Australian Brushtail possum has become
New Zealand’s most noted pest animal.
The possum has caused large scale
environmental and economic damage to
most parts of the country.
Possums are widespread throughout
Southland and Stewart Island, but are
absent from many offshore islands.
Possums are territorial with overlapping
home ranges of one to two hectares.
Possums produce up to two young a year.
New areas are colonised mainly through
young possums looking to find a home
range.
What is the problem?
Possums cause both economic and
environmental damage in Southland.
Possums are a vector for Bovine Tb in
Southland. Disease transmission occurs
when infected possums contact stock-feed
or are sniffed and licked by livestock.
Possums eat large amounts of pasture,
stock feed, crops and damage forest
plantings and horticultural crops.
Possums also have Suppression animal
status on mainland Southland and Stewart
Island.
Possums are an Exclusion animal on
offshore and inland islands.
Strategy Rules
1. Land occupiers within the 5% Residual
Trap Catch (RTC) area, depicted on the
attached map, shall control Possums on
land they occupy, at their own expense,
to at or below 5% RTC.
2. Land occupiers in the 10% RTC area,
depicted on the attached map, shall
control Possums on land they occupy, at
their own expense, to at or below 10%
RTC.
3. No person shall keep in captivity, sell,
offer for sale, propagate, transport
or release any Possums within the
Southland region including offshore and
inland islands.
Note: Residual Trap Catch (RTC) is a
nationally standardised possum monitoring
method using lines of leg-hold traps. The
%RTC represents the percentage of traps
which captured a possum. E.g. 5 possums
caught from 100 trap nights would be a 5%
RTC.
Pest Animal Factsheet
Control
Environment Southland Regional Pest
Management Strategy requires that land
occupiers assist with maintaining low
possum numbers.
Environment Southland staff can provide
advice and information regarding these
control options for possums:
• trapping
• poisoning
• night-shooting
• repellents
• commercial pest controllers
Trapping - traps for controlling possums
are available from farm supply stores. Traps
fall into three categories - kill traps, leg-hold
traps and live capture traps.
Fresh apple, orange or kiwifruit are effective
baits for possums. Their scent can be further
enhanced by sprinkling with cinnamon or
curry powder.
To achieve the best results, the trap should
be set close to suitable feeding or nest sites,
near possum pad runs or trees that possums
are known to frequent.
When trapping large areas of possum
habitat traps should be placed at 20 -100
metre intervals on lines 100 metres apart.
This ensures that a trap is within each
possum’s home range.
•
Kill Traps
Environment Southland lends out
“Timms” and “Possum Master” kill traps
to control small numbers of possums.
Both of these traps are very effective
and easy to use.
Kill traps set with fruit baits pose little
or no threat to domestic cats. Poultry
should be kept away. An ideal bait size
is about one quarter of an apple.
Possums are most active in the first four
hours after dark. If there is a concern
about pets coming into contact with
a trap, traps can be set early in the
evening and released prior to bedtime
with pets kept shut in during this time.
•
Leg-hold Traps
Leg-hold traps have proven to be one
of the most cost-effective methods of
trapping possums in areas where you
wish to control a large area, for example
a bush remnant on your property.
•
Cage Traps
Cage traps are an option in residential
or built up areas. If you catch non target
animals, they can easily be released.
Notes:
1) The law requires (Animals Protection Act)
that traps and snares are checked every 24
hours after setting to prevent unnecessary
suffering or pain to any animal caught. This
does not apply to kill type devices, but is still
advised.
2) The use of gin traps will be prohibited by
law from January 2008.
Poison - there are several poisons available
from rural supply stores that are effective for
possum control. The poisons available for
general public use are:
• Pestoff (Brodifacoum) – second
generation anticoagulant poison that is
suitable for bait station use. Pestoff is a
slow acting poison.
• No Possums (Cholecalciferol) - a
calcium elevating poison that causes
heart failure. Used in a bait station it has
a very long field life.
• Pindone – a first generation poison that
generally requires large quantities of bait
to be supplied continually.
These possum baits must be used in bait
stations. Bait stations help to confine the
bait to the target species and should be
placed at 100-150 metre intervals through
areas of possum habitat. Bait stations are
also available on loan from Environment
Southland.
For Pestoff and Pindone, fill the bait stations
initially, and then pulse feed at three weekly
intervals thereafter. This allows possums
that have been poisoned to die before more
bait is made available.
Pest Animal Factsheet
All poisons must be used and stored
in accordance with label instructions.
Poisoning in urban or built up areas is not
recommended. Ensure poison warning signs
are displayed.
Night-shooting - night-shooting is an
effective means of controlling small possum
populations. If shooting is used, a .22 rifle
and shotgun are the preferred firearms.
All the necessary precautions must be taken
when using firearms.
Repellents - repellents may deter possums
from damaging young trees, but do not
provide total protection. Repellents are not
practical for Tb control or protecting native
forests.
Repellents give short-term protection to
treated plants, however, killing possums is
the most effective means of control.
Garden shops, tree nurseries or farm
supply shops supply commercial repellent
preparations.
If using repellents on a small scale, an
egg “home brew” described below can be
considered:
Egg mix
4 eggs, 100 ml water-based paint, 900
ml water. Beat eggs then mix in waterbased paint, then add water. Pour through
strainer into spray applicator. This mix
does not persist as well as commercial egg
preparations and usually has to be reapplied
at three-weekly intervals.
Commercial Pest Controllers - pofessional
pest destruction firms can be used to
carry out possum control work. Contact
Environment Southland for information and
contractor details, or see the Yellow Pages
under Pest Control.
Advice & Information
To find out more information contact:
Biosecurity Officer
Environment Southland
Private Bag 90116, Invercargill
Phone
03 211 5115
Toll free
0800 76 88 45
Fax
03 211 5252
E-mail
service@es.govt.nz
Website
www.es.govt.nz
Pest Animal Factsheet
Figure 2 – Possum Residual Trap Catch Areas