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)