Field efficacy trial of the Curiosity® Feral Cat bait on Christmas Island

Progress Report: August – November 2008

Report prepared by Michael Johnston1, Dave Algar2 and Michael O’Donoghue3

1.Department of Sustainability and Environment

Arthur Rylah Institute PO Box 137, Heidelberg, 3084, VIC

2.Department of Environment and Conservation

PO Box 51, Wanneroo, 6065, WA

3.Scientec Research Pty Ltd 71 Yarra Street, Warrandyte, 3113 VIC

Field efficacy trial of the Curiosity® Feral Cat bait on Christmas Island Progress Report: August – November 2008

Aim To assess the efficacy of the Curiosity® Feral Cat Bait in reducing the population of feral cats within a tropical island site (the Christmas Island National Park, CINP). Methods Study Design

Consultative planning of the proposed work entailed a series of meetings with Parks Australia North staff (Darwin and Christmas Island), Christmas Island Phosphate and the Christmas Island Shire. Notification to the wider community was undertaken with a series of articles in the local newspaper called, (‘The Islander’). Further opportunities for raising community awareness were provided at an open meeting hosted by the Shire and also to year 10 students at the Christmas Island school. Study Activities

A network of 616 bait suspension devices (“BSD”) was established throughout the Christmas Island National Park (“CINP”). Each BSD consisted of a fabricated gantry device (see Figure 1) with a sand-pad, formed from powdered phosphate dust, placed underneath the bait to enable identification of species visiting the site. These devices were installed at 100m intervals throughout the study area at the edge of the slashed vegetation on the roadside verge, see map at Attachment 1. Two non-toxic baits were suspended from each BSD on the 14th October with daily monitoring of sand-pad activity and bait take beginning the following day. Toxic baits were provided at BSD sites (and its immediate neighbours) following removal of non-toxic bait(s) by feral cats.

Figure 1. Diagram of Bait Suspension Device (from Algar and Brazell, 2008)

The western portion of the CINP was treated as an non-poisoned area only following consultation with Lindy Lumsden (DSE Arthur Rylah Institute) who considered that the resident feral cats may influence black rats which in turn may have contributed to the decline of the Christmas Island Pipistrelle (Pipistrellus murrayi). Sixty monitor plots were installed across the site to provide an independent measure of cat activity (see Attachment 1). An audio lure (Felid Attracting Phonic, FAP) and urine scent lure were provided at the end of blind ‘set’. Cats had to walk past a single ‘rub stick’ coated with double-sided tape to investigate the lures (see Figure 2).

Figure 2. Monitor plot with rub stick and scent/audio lures

A spotlight survey was undertaken on three sequential nights prior to the bait trial in September. Cats were observed with a 100W spotlight by an operator standing in the tray of a utility travelling at 20km/h driven around a 30 km circuit along the main haul roads. The location of cat sightings was recorded using a GPS device together with notes regarding cat colour and size. A trapping program was conducted so that a proportion of the resident feral cats could be fitted with VHF radio collars. These animals were monitored to provide a further index of change within the larger population following application of toxic baits. Leghold traps were set in 20 and 50 L buckets (Figure 3a,b) to limit the capture of robber crabs and used fried chicken as a lure. Traps were generally placed at sites where feral cats had been observed during the spotlight survey and checked at least three times daily.

Figure 3a. Feral cat trapped in 20 L bucket leghold trap set Figure 3b. 50 L bucket leghold trap set.

Bait Attractiveness / Palatability Studies

The palatability of Curiosity® baits used in CINP was compared to the baits used on French Island (“FI”) and conventional Eradicat® bait. Each bait type was provided at a BSD in turn along a transect of 167 sites and monitored daily over four nights. The pH of baits was measured by placing baits into fresh water for an hour and then using a pH paper to assess pH. Two baits of each type were tested with one bait immersed whole while the other was sectioned longitudinally to allow greater contact with the sausage meat.

Materials

Traps (Victor Soft-Catch size 3), ancilliary equipment and FAPs were air-freighted from Perth. Buckets used in the construction of traps were sourced locally. Dry phosphate dust was provided by CIP. Seven thousand Curiosity® baits were produced by the Department of Environment and Conservation (DEC) bait factory at Harvey, Western Australia using commercial scale equipment. This facility also supplied Eradicat® baits. Scientec Research produced the FI baits on a domestic scale device. All baits were transported to Christmas Island as frozen freight. A large freezer was hired on the island to store the baits prior to use. The toxic pellets

(PAPP-HSDV) were prepared by Scientec Research as batch 4915 and freighted using an accredited hazardous goods courier to Christmas Island. Personnel

The project was staffed by a roster of 8 people (Table 1). A preliminary site visit took place between 25 August-5 September and the study was conducted between 26 September-1 November. Table 1. Tasks undertaken by project team

Date Name Tasks 25 Aug – 5 Sept Mike Johnston

Dave Algar Preliminary site visit: meetings, spotlighting, trapping and collaring feral cats

26 Sept – 16 Oct Dave Algar Install BSDs, hair traps, cat trapping, monitoring of bait take

3 Oct – 16 Oct Stef Hilmer Install BSDs, hair traps, cat trapping, monitoring of bait take

11 Oct – 26 Oct Neil Hamilton Mike Onus

Monitoring of bait take

16 Oct – 31 Oct Rob Brazell Dave Hawke

Monitoring of bait take, remove BSDs from haul roads, spotlighting.

26 Oct – 31 Oct Mike Johnston Sue Robinson

Monitoring of radio collared cats, meetings, remove BSDs from haul roads, spotlighting.

Results A total of twelve feral cats were trapped and fitted with VHF transmitter collars. Two further cats were euthanased due to injuries caused by robber crabs (Table 2). Table 2. Morphometric details of feral cats trapped and released with transmitter collar.

No. Sex / Weight Coat colour Collar freq Location 1 M 1.0kg Smoke grey 151.5800 48L 0568571 8840298

2 M 2.5kg Black and white 151.8500 48L 0571435 8832972

3 M 3.5kg Ginger 151.8085 48L 0571116 8837761

4 F 2.5kg Grey tabby / ginger Euthanased 48L 0569729 8839772

5 F 2.0kg Grey tabby 151.8960 48L 0571733 8838774

6 M 2.4kg Ginger 151.6690 48L 0570740 8834704

7 F 2.1kg Grey tabby 151.2180 48L 0565544 8841903

8 M 3.2kg Ginger Euthanased 48L 0568033 8840349

9 M 1.8kg Ginger 151.2800 48L 0569479 8842481

10 M 3.7kg Black and white 151.5480 48L 0571219 8843853

11 F 2.1kg Grey tabby 151.0200 48L 0571341 8837085

12 M 2.8kg Grey tabby 151.5295 48L 0571438 8838303

13 F 2.1kg Tortoise shell 151.5119 48L 0575338 8843953

14 M 2.9kg Ginger 151.1015 48L 0571215 8833429

The ‘sticky wicket’ monitor plots proved to be an unsuccessful tool in this study due to dust generated by passing traffic adhering to the adhesive tape and preventing collection of hair. Robber crabs also destroyed a number of the FAP audio lures. Fifteen feral cats were seen during the preliminary spotlight surveys (Table 3). Incidental observations of cats seen on the same roads during daylight contributed to a total of 42 animals known to be proximate to the main haul roads. Given these numbers we considered that there would be sufficient feral cats across the whole site to allow for the conduct of the trial.

Table 3. Summary of spotlight survey results

Date No. of cats seen 27 August 6

28 August 7

29 August 2

27 October 3

28 October 2 (heavy rain)

29 October 2

A total of 616 BSDs were installed throughout the study area. The observed bait take was substantially lower than anticipated and the trial was cut short after ten days. A total of 6160 device nights yielded 124 visits and 50 bait takes by cats were recorded (Table 4, Figure 4). Continuation of the trial as originally planned was not warranted as sufficient decline in bait take and cat activity would not have been demonstrated in the time remaining. Table 4. Summary of feral cat interaction with BSD.

Cat visit (free-feed) 68

Cat take (free feed) 10

Cat visit (toxic bait) 56

Cat take (toxic bait) 40

Figure 4. Feral cat approaching BSD

Black rats visited 6 BSDs and were considered to have accessed the bait on 4 of these occasions. The number of crab visits to BSDs was not recorded as it was assumed that all sites would be visited by crabs. However, a total of 78 crab takes were recorded and were subsequently attributed to a) baits being hung too low initially at some sites and b) the collar (i.e. bucket lid) used on the BSDs being smaller than those used previously (Algar and Brazell 2008). The toxicosis and subsequent death of a ginger cat was observed following consumption of baits by Mike Onus and Neil Hamilton on the 23rd of October – see Attachment 2. Bait attractiveness / Palatability Studies

The palatability comparison between bait types indicated that 1 Curiosity® bait, 2 FI baits and 2 Eradicat® baits were taken by feral cats. Disposal / Storage

A quantity of unused Curiosity baits remained in storage due to the premature closure of the baiting program. These baits were deep buried in the Christmas Island landfill by CINP rangers.

Unused PAPP HSDVs were placed in locked storage at the CINP depot and should be sufficient for re-use. Discussion In this trial, 40 toxicant baits were taken over a 10 day period and presumed to have been taken by feral cats. However, based on i) feral cat densities at the site, and ii) previous experience with the Eradicat® bait, this rate of bait consumption was considered poor. Ideally, the bait take and cat activity indices should start off high and decline as the trial takes place. In this case, the indices started low and remained low during the ten days. While a reduction of forty feral cats from within the park could be viewed as a reasonable outcome when compared to other techniques available to rangers at CINP, this result was insufficient as to be able to provide a demonstrable decrease in feral cat activity at the culmination of the trial for the purpose of i) presenting the data to the APVMA and ii) making claims about the ability of the product to effectively manage feral cat populations. A further complication to the issue of bait palatability was the early arrival of significant rains which triggered migration of red crabs on the island. Temporary road closures are instituted during the migrations which would have lead to difficulties in accessing all sites (Figure 5).

Figure 5. Sweeping red crabs off Murray Road to allow vehicle passage during early stage of migration

A variety of explanations for the poor bait-take have been considered and tested. These include;

• Cats not being hungry. (Comment: all animals trapped were under-weight, Figure 6)

• Cats having moved away from roads. (Comment: cats were still seen on roads and most radio-collared cats had not moved far from where they had been trapped / released.

• The BSDs triggered a neophobic reaction in cats. (Comment: neophobia was not an obvious problem in earlier studies at this site or on the Cocos (Keeling) Islands. Additionally, the bucket lids were removed from a portion of sites but no greater visitation by cats was observed.

• Crabs prevented cats from accessing the baits. (Comment: this was not an obvious problem in earlier studies. There was no increase in cat activity was recorded where crab abundance was low.

• The bait was not as attractive to cats, and/or was not as palatable as it should have been.

Figure 6. Sedated feral cat fitted with radio collar. Note poor body condition.

In respect of these possible factors affecting bait uptake, the most likely explanation appears to be that related to bait attractiveness / palatability. This conclusion is based on the following:

1. Unbuffered Eradicat® baits were removed from frozen storage on the Cocos (Keeling) Islands and established on 20 BSDs on Home Island and West Island. Three BSDs received a ‘visit only’ from feral cats while a further twelve sites had baits removed by feral cats. These results indicate that the original Eradicat® bait was readily taken by feral cats in a similar environment and that the BSD continues to remain viable. The ‘ready take’ of the Eradicat® baits suggests that there was a problem with the Curiosity® baits.

2. A key difference in bait properties was noted. This was the absence of oils sweated from the Curiosity®

baits, contrary to the behaviour of the Eradicat® and FI baits. In particular, the bait skin was observed to have become ‘rubberised’ which may have formed a seal preventing sweating of the bait fats/oils. There was also a lesser apparent visibility of fat (strands) in the baits.

3. A comparison of the pH of the baits with those prepared for the FI study, and also recently

manufactured Eradicat® baits (i.e. baits that had not been pH buffered). There was no difference between the entire and sectioned baits with Curiosity® and FI baits which exhibited pH’s of ca. 7.5 and 8.5 respectively. The pH of the the entire Eradicat® bait was 6.0 and 5.0-5.5 in the sectioned bait (Figure 7). These results suggested that pH per se was not the cause of loss of attractiveness / palatability.

Figure 7. Checking pH of baits

In order to demonstrate that the PAPP pellets were fit-for-purpose, a feral cat (4.0kg male) was trapped in the landfill (i.e. outside of the study area) on the 30th of October and was provided with a bait containing a PAPP HSDV. This cat failed to consume the Curiosity® bait on the night of the 30th. However, the PAPP pellet was transferred into a pilchard which was readily consumed on the 31st. The time to death for this animal was approximately four hours. The rejection of the Curiosity® bait and acceptance of the pilchard is a further indication of attraction / palatability issues with these baits. In considering the above observations, it was determined that the attractiveness / palatability problems may have arisen as a result of the manufacture processes used to produce this batch of Curiosity® Feral Cat Baits. In particular, this was the first batch of baits produced on the large scale equipment at DEC Harvey. That is, the process was at the research – development scale up stage. Baits used for the French Island bait efficacy trial had been produced on small scale equipment by Scientec. In respect of this production process, the key difference between the Eradicat® and the Curiosity® bait is the requirement to buffer the bait emulsion for the Curiosity® product. The HSDV requires the bait to be at a pH ≥7.5 to prevent premature failure of the acid-sensitive coating matrix. The Eradicat® bait has a pH of approximately 5.0. Chemical analysis conducted between three bait types determined that there was significant chemical differences between baits and that these differences are likely to influence palatability of the bait, see Attachment 3. In considering the process and equipment used in bait manufacture at DEC Harvey, modifications to the buffering and mixing protocols were proposed by Scientec. These proposals, trialled by Rob Brazell in late December and early January, appear, at this stage, to have yielded a product with the requisite properties, (i.e. odour, marbling of fats, sweating, etc). Acknowledgements Funding was sourced from the Australian Government Department of Environment, Water, Heritage and the Arts. In-kind contributions were provided by Parks Australia North and Christmas Island Phosphates. Joy Wickenden and Mike Misso are recognised for their considerable efforts to support this project. Thanks to Dave Tonkin (Subiaco Shire) for establishing the BSDs on Cocos (Keeling) Islands. Permits were granted to import PAPP onto the island under the APVMA permit IOT0001. A research permit was granted by Parks Australia for conduct of work within Christmas Island National Park. The DSE Animal Ethics Committee approved protocol no. 08/15 which described the works to be undertaken in the trial. A referral under the Commonwealth Environment Protection and Biodiversity Conservation Act 1999 found that this project was not a ‘controlled action’. Reference Algar, D., Brazell, R.I. (2008): A bait-suspension device for the control of feral cats. Wildlife Research 35: 471-476.

Proposal for repeat trial To repeat the bait efficacy trial in CINP following production of appropriate baits and onset of the next dry season (approximate timing March / April 2009). Sufficient PAPP pellets are held at the CINP office for the conduct of this trial. The trial would be undertaken by three people with assistance sought from local agencies when required. The trial will involve;

• Re-establish site

• 5 days of pre-bait monitoring at the 60 monitor plots. Radio tracking

• 20 days of baiting (all BSDs will be fitted with non-toxic baits initially. Toxic baits will be fitted at sites (and its neighbours) when free-feed has been taken by a cat)

• 5 days of post bait monitoring at the 60 monitor plots. Radio tracking

• Site clean-up Unknowns

• behaviour and availability of food for feral cats in early dry season

• how many of the 12 feral cats fitted with collars will be alive and can be relocated Permits A permit has been sought from the Attorney Generals Department for use of PAPP on Christmas Island. A reapproval of the AEC protocol has been sought from the DSE AEC. The earlier decision under the Commonwealth EPBC Act is supported for a repeat of the trial and thus no further permit is required. Services sought in kind from local agencies 4wd ute ATV x 2 Fuel (and jerry cans) Phosphate Accommodation – Pink House Freezer for baits Additional budget sought from Department of Environment, Heritage and the Arts

Flights $8700

Baits $1800

Freight $2500

DSE staff – Mike Johnston and Mike Lindeman $23400

DEC staff field allowances - Dave Algar $3000

Food (37 days) $3159

Corflute collars for BSD $500

Total cash cost $43059

Attachment 1

Attachment 2 Observation by Neil Hamilton and Mike Onus of a feral cat on Christmas Island

consuming Curiosity Feral Cat Baits. Whilst doing our morning cat monitoring routine we observed a ginger cat taking the cat bait from the bait- suspension gantry. We previously knew this cat was coming to the bait stations as we had seen it on more than one occasion near BSD no 235. On the morning of 23 October we again approached the gantry slowly and noticed the ginger cat waiting. We stopped at the BSD and suspended two toxic baits. We also placed two more toxic baits on a small log next to the BSD. As we drove on to our next site we observed the ginger cat emerge and take the baits from the BSD. The cat took the baits into the bush and a few minutes later came back out and started eating the other two baits off the log. The time of bait consumption was 0930 hrs. Mike walked up and placed two non-toxic baits on the BSD. Within ten minutes the cat came out jumped up again and pulled them off. At 1015hrs we decided to place two more toxic baits again on the gantry. The cat returned, jumped up and pulled off one of the baits and re-entered dense vegetation. The total of baits taken (i.e. not necessarily consumed) was five toxic baits and two non-toxic. We quietly approached the site on foot to observe the cat which appeared to have become sleepy with erratic breathing. The cat tried moving about, but would sometimes lose balance and fall over. We observed the cat lay down under the vegetation and breath erratically. Within about an hour the cat got up and moved off into the bush about 15 metres from the road. We followed to keep it in view and noticed it lying down and continued breathing erratically, which became faster as time progressed. It also licked its paws a lot. Actual time of death was 1120hrs with duration of toxicosis being one hour and forty minutes.

SCIENTEC RESEARCH PTY LTD

A.B.N. 32 058 744 371

Scientific and Technological Research Management, Consultancy and Best Practice

Scientec Research Pty Ltd, Address for Correspondence: 71 Yarra Street, WARRANDYTE 3113, Victoria, Australia.

Phone [Mobile]: +61 (0)409 931 886; Facsimile: +61 (0)3 9844 2076; e-mail: scientec@labyrinth.net.au

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Our Ref: Sci2448b L D Algar (141208).wpd 14th December, 2008

Dave Algar Department of Environment and Conservation (WA) P.O. Box 51, WANNEROO, WA, 6946 pH: 08 9405 5145 e-mail: Davea@dec.wa.gov.au

COMMERCIAL-IN-CONFIDENCE Dear Dave, Re: Curiosity7 Emulsion Fat Analysis

Notes for your consideration in regard to the analysis of bait emulsion samples for fat content [free fatty acids, triglyceride and fatty carboxylate salts ('soaps')]. Please note that there are a number of aspect to the analysis which I have raised with the analyst(s) to which I am yet to receive a response. However, these answers will have no material effect on the general findings from the analysis, a summary of which follows. 1. Three samples were provided for analysis, namely (i) a French Island baits (prepared by Scientec), (ii) a

Curiosity7 bait from the batch prepared for Liz Denny (IACRC), and (iii) a Curiosity7 bait from the batch prepared for the Christmas Island trial.

2. Portions of each of the baits were extracted with either:

(a) a neutral organic solvent (to dissolve mono-, di-, and tri-glycerides and also free fatty acids); or

(b) an acidic organic solvent (to dissolve mono-, di-, and tri-glycerides, free fatty acids, and also fatty acid carboxylates, or 'soaps').

3. There were definitive differences between the extracts from all three baits, as follows: i) the extract from the Scientec baits consisted of:

ca. 60 mono-, di- and tri-glyceride; and ca. 40 as free fatty acid.

There appeared to be no fatty acid carboxylates ('soaps') present. ii) the extract from the Liz Denny/IACRC baits consisted of:

ca. 100 mono-, di- and tri-glyceride.

Attachment 3

COMMERCIAL-IN-CONFIDENCE

Scientec Research Pty Ltd, Address for Correspondence: 71 Yarra Street, WARRANDYTE 3113, Victoria, Australia.

Phone [Mobile]: +61 (0)409 931 886; Facsimile: +61 (0)3 9844 2076; e-mail: scientec@labyrinth.net.au

H:\DNRE\CATS\FIELD TRIAL SITES\CHRISTMAS ISLAND\TRIAL OF CURIOSITY FERAL CAT BAIT ON CHRISTMAS ISLAND _DA 20 JAN09.DOC 23Jan09 Παγε 13 οφ 13

There appeared to be no free fatty acid or fatty acid carboxylates ('soaps') present.

iii) the extract from the Christmas Island baits consisted of

ca. 70 mono-, di- and tri-glyceride; and ca. 30 as fatty acid carboxylates ('soaps').

There appeared to be no fatty free fatty acid present.

4. In hindsight an analysis of an Eradicat7 bait should also have been undertaken (and still could).

This would have indicated whether free fatty acids are a normal 'product' of the preparation. It seems reasonable that some, at least, free fatty acids would normally be present (acid catalysed hydrolysis of triglycerides) and it is likely that it is the free fatty acids which 'sweat' when the baits are placed in the sun.

The difference between the two batches of Curiosity7 baits is interesting. The apparent lack of fatty acid carboxylates ('soaps') in the Liz Denny/IACRC baits suggests that these may have performed 'satisfactorily' (results from the trial are still 'in the post'). We have no data to indicate the likely effect of fatty acid carboxylates ('soaps') being present in the emulsion (baits). However, it seems reasonable to anticipate that they might bind/emulsify the residual 'fats' thus inhibiting release (sweating).

___________________________________

Hope this summary makes sense and is sufficient for your immediate needs. However, if there are any uncertainties as to the above, or you have any comments or questions, please feel free to contact me on 0409 931 886, or by e-mail at scientec@labyrinth.net.au.

Regards M. O’Donoghue

cc. J. Morris enc. 'PAPP' Lab Book

M. Johnston File