CHEW-TRACK-CARDS Development of a New Mammalian Pest Detection Device

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John Robinson
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1 CHEW-TRACK-CARDS Development of a New Mammalian Pest Detection Device P. Sweetapple, G. Nugent, Landcare Research, P.O. Box 40, Lincoln Contracted by the Animal Health Board and FRST

2 Why do we Need a New Pest Detection Device? Most current methods are inefficient at very low pest densities. Efficient mapping will permit cheap targeted control or even local elimination of low-density pests. Possible improvements to current interference devices (e.g. WaxTag ).

3 WaxTag Features: Light, easy to deploy Unlured wax block Limited detection surface for multiple pest detection Added bait exposed to weather Cost: $0.85/unit

4 Chew-Track-Card

5 Purpose of CTCs To cheaply detect and map the distribution of possums and other small mammalian pests at low density following possum control. Primarily a mapping tool rather than a density index tool for use in targeted mopup operations

6 Features Simple and low cost 9x18 cm folded coreflute card. Unit cost: c. $0.10. Easy to deploy units over c. 4 km per day in remote terrain ($7.00/ha at 250-m spacing) Multiple species detection Possums, stoats, ferrets, hedgehogs, rats, mice (cats, dogs, pigs, kea, weka) Highly palatable baits peanut butter, pet food etc to maximise sensitivity Two detection modes Tooth impressions and footprint recording

7 Possums Incisor pair 6 mm Card edge crushed but not cut

8 Rats Rat incisor-pair impressions Bites Cleanlycut edges Rat prints

9 Mice Chewing between channels, on one surface Roughly chewed edges

10 Carnivores Hedgehog (mandible) Hedgehog (upper jaw) Cat Stoat 8 mm

11 The art of rat and mouse tracking Mouse tracks Rat tracks 1 cm 1 cm Mouse tracks Tracking tunnel prints

12 Possum Detection Efficiency Hauhungaroa Range. Compared Winter05 post control Trap (RTCIs) and summer 05/06 CTC survey Method Effort N. possums Freq. Traps 106 lines (21.2 km) % CTCs 2992 cards (150 km) % Detection rates (possums/day) Traps CTCs 0.009/day >0.275/day CTCs x more efficient at detecting possums (even allowing for 50% reduced post control bias)

13 Transformed CTCI CTC-RTC Calibration (Lake McKerrow) 200% 100% y = 5.89x R 2 = 0.69** 0% 0% 20% 40% Transformed TCI (Possum interference rate on CTCs over 6 nights prior to three nights of leg-hold trapping) Possum CTCI is strongly correlated with RTCI

14 Other Pest Detection Hauhungaroa R. 2005/06 Species No. Cards Frequency (%) Proportion tracks only Possum Rat Mouse Hedgehog Stoat High sensitivity for rodents? Poor for stoats? Hedgehogs unclear?

15 Possum CTC ratio Rat Interference Bias Hauhungaroa Range y = 0.033x R 2 = 0.81, F 1,7 = 30.49, P = Transformed rat CTC index Rats suppress possum CTCIs Hauhungaroa ; Possums CTCI on rat chewed cards were low relative non rat chewed cards

16 Possum CTCI ratio Rat Interference Bias Whirinaki Ratio differs from zero 2.5 t16 = 4.99, P < % 100.0% 200.0% 300.0% 400.0% Transformed rat CTCI Rats are also excluding possums from cards but pattern different from the Hauhungaroa Range

17 Number of cards Rat Repellent Trial Hauhungaroa Range Rats Peanut butter Rat repellent Rat chew score Rats chewed repellent lightly or not at all

18 Number of cards Rat Repellent Trial Hauhungaroa Range Possums Peanut butter Rat repellent Possum chew score Possums chewed rat repellent as heavily at the peanut butter (P > 0.5)

19 Rat Avoidance Strategies Repellents: Eucalyptus oil*, Tea-tree oil*, Curry powder*, Chilli powder, Bitrex, Cinnamimide, Mineral turpentine, orange oil, FeraFeed (Connovation)* * Moderately repellent when rat abundance was low Baiting Strategies - liquid baits (partially successful) - floppy sets (short-term effect) - combinations of above??

20 CTC sets to reduce rat interference Liquid bait set Floppy set

21 Possum Bait Development Three stage pen trial Base matrix: peanut butter/white flour/wholemeal flour with and without 20% icing sugar Lures: artificial lures: orange/aniseed/raspberry/curry (1%) natural lures: fresh clover/honey/mealworms (10%) Applied to CTCs: Field trial (Craigieburn) Sugared peanut butter with honey or clover

22 Relative chew index Palatability Pentrial a a,b a,b,c peanut butter white flour honey clover b,c,d curry raspberry c,d aniseed -0.3 Bait d

23 Percent detection Possum Bait Development Craigieburn field trial Possums, P = Mice, P < Clover CTC Honey CTC Clover/Honey Waxtag Detection Device Clover in sugared peanut butter best

24 Possum Detection Probability - Field Trial (Hauhungaroa Range) Initial Survey (500 ha): -Line spacing 250 m - CTC spacing 50 m Follow-up surveys: - 25 CTCs/traps on 4 ha grids - DNA extracted from CTCs and trapped possums: - mark-recapture est. of possum nos. - estimates of detection probability

25 Possum Detection Probability Results 20 detection foci surveyed 58 possum-chewed CTCs (6-7 fine nights) 15 full unmixed genotypes 11 unique genotypes 18 possums captured + 2 escapes (6 fine nights) 19 genotypes 4 matches with CTC genotypes (recaptures) 47 possums present 38-42% trappable 81-96% detected by CTCs

26 Summary Cheap and easy to deploy Very sensitive to possums and rodents Bait is protected from weather Biases when possums low and rats high (and vice versa?) Highly possum-palatable bait developed - gives high possum detection probabilities

27 Ongoing Development AHB project R-10709: No Possums, No Tb Undertake two successive possum map-andeliminate surveys in 1600 ha of Central Hauhungaroa Range to determine efficacy and cost of possum/tb eradication (underway). Investigate impact of transect and device spacing on operational success. Further rat repellent trials Seasonal Detection probability mop-up trials (proposed)

Project No: R

Project No: R-80660-01 Effects of Prefeeding on Ground and Leaning-board Trap Sets, and the Relationship between WaxTag and Trapcatch Possum Monitoring Indices. A Partial Replication of Project R-80660