Mandy Barron, Dean Clarke, Pen Holland, Mike Perry, Wendy Ruscoe, Peter Sweetapple, Caroline Thomson (Landcare Research) James Griffiths (DOC) Rapid reinvasion of pest control areas: New results from Project Kaka in the Tararua Ranges
Mandy Barron, Dean Clarke, Pen Holland, Mike Perry,
Wendy Ruscoe, Peter Sweetapple, Caroline Thomson
(Landcare Research)
James Griffiths (DOC)
Rapid reinvasion of pest
control areas: New results from Project Kaka in
the Tararua Ranges
Rationale for pest control
• To mitigate impacts on
indigenous biodiversity
• On-going effort required
due to pest population
recovery (time)
• Spatial extent of pest
control and its benefits
(space)
Spatial extent of pest control
Control
applied
Spatial extent of pest control
Core effect
Spatial extent of pest control
Control
applied
Spatial extent of pest control
Halo effect
Project Kaka
• DOC initiative
• Large scale control
– 22000 ha Tararua
Forest Park
• 3-yearly aerial 1080
• First control
November 2010
Image: www.doc.govt.nz
Department of
Conservation monitoring:
• Possums, rats, stoats,
birds & vegetation
• Tmt/non-tmt
• In situ pest response
Department of
Conservation monitoring:
• Possums, rats, stoats,
birds & vegetation
• Tmt/non-tmt
• In situ pest response
LCR monitoring:
• Same as DOC, -birds,
+inverts.
• Across boundary
• Immigration
2 x 5 km transects across
the pest control boundary
Waitewaewae
Totara Flats
0m 1000m 2000m -1000m -2000m
0 m 500 m 1000 m
Pest Control Area No Pest Control
Monitor lines
Wax tag line (200 m) 5 Pitfall traps
Tracking tunnel line (500 m) Weta hotel
Kamahi, toro and
rimu trees
Rats: pre-control
Rats: 3 mths post-control
Nov 2010
Rats: 6 mths post-control
Rats: 9 mths post-control
Rats: 12 mths post-control
Rats: 15 mths post-control
Rats: 18 mths post-control
Rats: 27 mths post control
Rats: 30 mths post-control
Weta: 9 mths post-control
Weta: 12 mths post-control
Weta: 15 mths post-control
Weta: 18 mths post-control
Weta: 27 mths post-control
Weta: 30 mths post-control
Weta hotel occupancy
Weta vs. rats
0.0 0.2 0.4 0.6 0.8 1.0
0.0
0.2
0.4
0.6
0.8
1.0
Rat tracking rate - 6 months prior
We
ta t
rackin
g r
ate
- c
urr
en
t
Possum abundance (wax tags)
Distance into 1080 zone
BM
I (%
)
0.00.20.40.60.8
0.00.20.40.60.8
0.00.20.40.60.8
0.00.20.40.60.8
0.00.20.40.60.8
0.00.20.40.60.8
0.00.20.40.60.8
0.00.20.40.60.8
0.00.20.40.60.8
-2000 -1000 0 1000 2000
Aug-1
0N
ov-1
0F
eb-1
1M
ay-1
1A
ug-1
1N
ov-1
1F
eb-1
2N
ov-1
2F
eb-1
3
Possum browse on kamahi
Distance into 1080 zone
Fo
lia
r B
row
se
In
de
x (
%)
0102030405060
0102030405060
0102030405060
0102030405060
0102030405060
0102030405060
0102030405060
0102030405060
-2000 -1000 0 1000 2000
Aug-1
0N
ov-1
0F
eb-1
1M
ay-1
1A
ug-1
1N
ov-1
1F
eb-1
2N
ov-1
2
Possums: 1.5 yrs post-control
FBI kamahi: 1.5 yrs post-control
Spatial & temporal extent of
control on pests
• Core effect of 1080 treatment on rat
abundance but resulting in more rats inside
than out (competitive release?)
• Location and timing of recovery suggests
immigration rather than in-situ breeding
responsible for rapid increase in rats at
edges
• Difference in possum abundance at edges
driven more by habitat /resources than by
treatment effects?
Spatial & temporal extent of
control on biodiversity
• Complicated!
• Both weta and kamahi showed initial
response to consumer abundance but over
time improved across transect despite high
consumer abundance
• Multiple cycles operating:
– Seasonal
– Masting
– Control operations
Acknowledgements
• Funding: Ministry of Business, Innovations
and Employment, Contract no: C09X0909
• Dave Carlton, Ben Reddiex (DOC)