A report prepared for the Kangaroo Island Natural ......District of Kangaroo Island (-35.84651˚S,...

A report prepared for the

Kangaroo Island Natural Resources Management Board

November 2019

Technical report on Kangaroo Island feral cat research studies and control trials 2016–2018 2

NATURAL RESOURCES KANGAROO ISLAND

The views expressed and the conclusions reached in this report are those of the authors and

not necessarily those of persons consulted. Natural Resources Kangaroo Island shall not be

responsible in any way whatsoever to any person who relies in whole or in part on the

contents of this report.

CONTACT DETAILS

Natural Resources Kangaroo Island

37 Dauncey Street

Kingscote SA 5223

Phone: (08) 8553 4444

Email: [email protected]

YEAR OF PUBLICATION

2019

© Natural Resources Kangaroo Island

This document may be reproduced in whole or part for the purpose of study or training,

subject to the inclusion of an acknowledgment of the source and to its not being used for

commercial purposes or sale. Reproduction for purposes other than those given above

requires prior written permission from Natural Resources Kangaroo Island.

This project was supported by the Kangaroo Island Natural Resources Management Board,

through funding from the Australian Government’s National Landcare Program with in-kind

support through the Government of South Australia.

FOR BIBLIOGRAPHIC PURPOSES THIS PAPER SHOULD BE CITED AS

Natural Resources Kangaroo Island. 2019. Technical report on Kangaroo Island feral cat

research studies and control trials 2016–2018. Report to the Kangaroo Island Natural

Resources Management Board.

Note: Additional data was collected during this project that has not been presented in this

report. The results of any future analysis of this data will be published as and when they

become available.

FRONT COVER IMAGES

Left: Feral cat investigating a non-toxic bait.

Right: Captured feral cat inside a cage trap.

mailto:[email protected]


Contents 1. Acknowledgements ........................................................................................................................................................... 5

2. Introduction .......................................................................................................................................................................... 6

3. Study Area ............................................................................................................................................................................. 6

4. Movements and home range ........................................................................................................................................ 8

4.1 Methods ....................................................................................................................................................................... 8

4.2 Results .......................................................................................................................................................................... 9

4.3 Discussion ................................................................................................................................................................. 10

5. Cage trapping trial ........................................................................................................................................................... 12

5.1 Methods ..................................................................................................................................................................... 12

5.2 Results ........................................................................................................................................................................ 13

5.3 Discussion ................................................................................................................................................................. 14

6. Baiting trial .......................................................................................................................................................................... 15

6.1 Methods ..................................................................................................................................................................... 15

6.2 Results ........................................................................................................................................................................ 16

6.3 Discussion ................................................................................................................................................................. 18

7. Conclusions ......................................................................................................................................................................... 20

7.1 Density ........................................................................................................................................................................ 20

7.2 Movement patterns and home range sizes ................................................................................................. 20

7.3 Control methods .................................................................................................................................................... 20

7.4 Key Recommendations for Phase Two .......................................................................................................... 21

8. References ........................................................................................................................................................................... 22

Appendix A ................................................................................................................................................................................... 24


Tables Table 1) Home range estimates for 14 collared feral cats ........................................................................................... 9

Table 3) Number of trap nights used during the cage trapping trials .................................................................. 13

Table 4) Cage trapping effectiveness ................................................................................................................................. 13

Table 5) The fate of each of the 169 baits recorded during the trial ..................................................................... 17

Table 6) Consumption of baits by feral cats .................................................................................................................... 17

Table 7) Tolerance of native animals observed consuming baits to 1080 (from APVMA 2008)................. 19

Figures Figure 1) Project study area ..................................................................................................................................................... 7

Figure 2) Senior field officer Dave Dowie fitting a radio collar to a sedated female cat (left) and a

collared adult male ginger cat captured on camera within the study zone ......................................................... 8

Figure 3) Home ranges and GPS points of 14 collared feral cats............................................................................ 11

Figure 4) Feral cat entering a cage trap. ........................................................................................................................... 12

Figure 5) Non-toxic Eradicat® bait in front of a Reconyx™ HC600 camera. ...................................................... 15

Figure 6) Feral cat consuming a non-toxic Eradicat® bait ........................................................................................ 16

Approval This report was approved for release on 29/11/2019 by Damian Miley, Regional NRM

Manager, Natural Resources Kangaroo Island.


1. Acknowledgements

The project team sincerely thanks all private landholders involved in the project who

cooperated with us and allowed us to conduct fieldwork activities on their properties.

We would also like to thank Pat Hodgens (Terrain Ecology) for his advice on the project

design, and for conducting and managing the fieldwork.

Particular thanks also go to Bronwyn Fancourt of Biosecurity Queensland and John Read and

Katherine Moseby of Ecological Horizons who provided expert advice on the study design.

We would like to thank Dave Dowie, Sandra Leigh, Brenton Florance, Nick Markopolous, and

Ilse Pickerd for conducting the fieldwork elements of this project, with help from interns

Sarah Leeson, Gavin Trewella, Richard Scott and Kate Cornelson.

We would also like to thank the many volunteers who assisted with various stages of this

project.

This project was funded through the Office of the Threatened Species Commissioner,

Environment Department of the Australian Government. The project also received additional

support from the Kangaroo Island Natural Resource Management Board.


2. Introduction

In 2015, the Kangaroo Island Natural Resources Management Board partnered with the

Kangaroo Island Council to develop a prospectus that proposed a three-phase feral cat

eradication program for Kangaroo Island (Natural Resources Kangaroo Island 2015).

Phase One of the program was intended to be the research and development phase. This

phase planned to conduct rigorous trials of various cat control tools in a range of island

landscapes. Applied research into the behaviour and ecology of feral cats, particularly cat

density, movement patterns and home ranges, was also to be undertaken. This information

would serve to inform eradication efforts in the subsequent phases.

In June 2016 the Australian Government, through the Office of the Threatened Species

Commissioner, provided funding for Phase One of the Kangaroo Island Feral Cat Eradication

Program (FCEP) to be carried out between July 2016 and July 2018. This report summarises

the results of the research studies and control trials undertaken during this period, and

presents recommendations for the continuation of the program.

The aims of Phase One of the FCEP were to:

1. Determine feral cat density within the study area.

2. Investigate the movement patterns of feral cats and their home range sizes.

3. Determine the effectiveness of a range of feral cat control methods.

4. Provide recommendations for Phase Two of the FCEP.

3. Study Area

The project was conducted in the Isthmus Management Zone (IMZ) in the Pelican Lagoon

District of Kangaroo Island (-35.84651˚S, 137.751468˚E) (Figure 1). The IMZ covers

approximately 59 square kilometres (km2) or 5,900 hectares. The topography of the IMZ is

relatively flat, however there is a large sand dune field in the south west of the study area.

Land tenure is primarily privately-owned properties, with some local and State Government

land. 57 percent of the land in the IMZ has been cleared for agriculture, although much of it

has not been actively used for agriculture for many years. The remainder of the IMZ consists

of patches of remnant mallee and coastal heath vegetation and smaller areas of revegetated

bushland.

The IMZ was chosen as the project study area as it was identified as being a critical zone for

Phase Two of the Feral Cat Eradication Program. A feral cat barrier fence will be erected in

the middle of this zone across the narrow isthmus that joins the Dudley Peninsula to the

western landmass of Kangaroo Island. This fence will isolate the feral cat population on the

Dudley Peninsula and enable eradication without incursions of feral cats from the west. Once

eradication on the Dudley Peninsula is complete, the program plans to proceed to eradicate

feral cats from the remainder of Kangaroo Island.


Figure 1) Project study area


4. Movements and home range

4.1 Methods

15 feral cats were captured in cage traps and then fitted with W500 Wireless GPS Logger /

VHF transmitter collars (Advanced Telemetry Systems, Isanti, Minnesota, USA) (Figure 2). GPS

units for all cats were programmed to attempt to record position coordinates seven times

every 24 hours (at 01:00, 03:00, 05:00, 12:00, 19:00, 21:00, 23:00), apart from:

» Cat_An: GPS unit recorded the position once per day (at 01:00) for two or three days

and then recorded the position every 15 minutes for 24 hours before returning to

recording the position once a day.

» Cat_Ja: Eight positions per day: 01:00, 03:00, 05:00, 08:00, 12:00, 16:00, 19:00, 22:00.

» Cat_Ki: Six positions per day: 02:00, 06:00, 12:00, 20:00, 23:00.

» Cat_Ma: Eight positions per day: 01:00, 03:00, 05:00, 08:00, 12:00, 17:00, 20:00, 23:00.

» Cat_Vl: Eight positions per day: 01:00, 03:00, 05:00, 08:00, 12:00, 16:00, 19:00, 22:00.

This variation in positional data collection is thought to be purely accidental.

The length of time that each study cat was tracked varied from 21 to 396 days. At the end of

the study period, all cats that had not died from natural causes were humanely euthanised

and the collars retrieved. GPS data were downloaded from the collars using the W100

Remote Communications Module (Advanced Telemetry Systems, Isanti, Minnesota, USA).

GPS data were used to generate Minimum Convex Polygons (MCPs) of 95% and 100% using

the R™ software program (R Core Team 2018) and the adehabitatHR package (Colenge

2006). MCPs of 95% (i.e. the smallest area that includes 95% of position fixes for each cat)

were selected to represent the home range while MCPs of 100% (i.e. the smallest area that

includes 100% of position fixes for each cat) were used as the total area of occupancy and

for comparison with previous studies.

Figure 2) Senior field officer Dave Dowie fitting a radio collar to a sedated female cat (left)

and a collared adult male ginger cat captured on camera within the study zone (right).


Home range curves were also generated for each cat using the R™ software program (R Core

Team 2018). These curves were used to determine if there was a high likelihood that enough

data points were collected to generate polygons that accurately reflected the actual home

ranges of these cats. The closer the curve was to approaching an asymptote the higher the

likelihood of an accurate home range.

4.2 Results

While useable positional data was collected for all 15 cats, the home range curve for Cat_An

did not approach an asymptote and has been excluded from these results (see Appendix A).

The home range (MCP95) for female feral cats (n = 9) varied from 1.49 km2 to 3.88 km2 with

a mean home range for females of 2.70 km2 (sd = 0.86) and a median of 2.60 km2. The home

range for male feral cats (n = 5) varied from 2.77 km2 to 10.26 km2 with a mean home range

for males of 6.26 km2 (sd = 3.34) and a median of 6.90 km2. The mean home range for all

cats in this study was 3.97 km2 (sd = 2.65) with a median of 3.01 km2 (see Table 1).

While the mean home range size of male feral cats was larger than females this difference

was not statistically significant (two-sample t(4) = 2.34, P = 0.08).

Table 1) Home range estimates for 14 collared feral cats

Cat ID Sex No of days No of fixes

Home

range

(MCP95)

Area of

occupancy

(MCP100)

MCP100 -

MCP95

Cat_Am Female 316 2168 2.20 3.32 1.12

Cat_Br Female 69 465 2.20 2.72 0.52

Cat_Go Male 384 2621 8.46 50.47 42.01

Cat_Ha Female 163 1274 3.76 4.05 0.29

Cat_Hi Female 396 2584 1.78 3.54 1.76

Cat_Ja Female 23 171 1.49 2.18 0.69

Cat_Ju Female 292 2228 2.60 2.93 0.33

Cat_Ki Male 140 670 6.90 10.16 3.26

Cat_Ma Female 82 535 3.32 4.36 1.04

Cat_Mi Female 84 533 3.10 3.78 0.68

Cat_Ne Male 118 725 2.77 4.07 1.30

Cat_Te Female 315 2369 3.88 5.88 2.00

Cat_Tr Male 21 135 2.92 5.50 2.58

Cat_Vl Male 332 2563 10.26 15.66 5.40

Mean 3.97 8.47 4.50

Male mean 6.26 17.17 10.91

Female mean 2.70 3.64 0.94


Male cats appeared to be more likely to venture away from their home range with 80% of

male cats (n = 4) increasing their total area of occupancy by more than 2 km2 from their

home range. One male cat went on several significant trips outside of its home range,

increasing its total area of occupancy by 42 km2 from its home range.

Conversely, no female cats increased their total area of occupancy by more than 2 km2 from

their home range, indicating that they may be more likely to remain close to their home

range.

Interestingly, the one cat that was excluded from the analysis as the home range curve did

not approach an asymptote was also the only cat that was identified as a juvenile. This

female cat also had the smallest home range of the females (1.34 km2) and the largest total

area of occupancy of the females (10.87 km2). It is possible, therefore, that this cat was still

attempting to establish a home range.

The home ranges and position fixes for all cats are presented graphically in Figure 3.

4.3 Discussion

This study showed that there is variability in the home range size of feral cats, both within

sexes and between sexes.

A similar study by Bengsen at el (2012) calculated the mean MCP100 for 13 cats on the

Dudley Peninsula to be 7.39 km2 (median 5.97 km2) slightly less than our calculated mean of

8.47 km2 (median 4.06 km2). They also concluded that there was no significant difference

between the home range sizes of males and females.

An earlier study by Paton (2003) determined the home ranges for 30 feral cats in the Murray

Lagoon area of Kangaroo Island. The mean home range for adult cats was calculated as

1.6 km2 for males and 1.45 km2 for females. However, this study only used data from a

maximum of three days and therefore may be understating the true home ranges of these

cats.

When using control devices to reduce feral animal populations it is important to deploy

them at densities that maximise the chances of each animal encountering at least one

control device. The smallest home range in our study was 1.49 km2 which (drawn as a circle)

gives a radius of 690 metres. Therefore no control device should be more than 690 metres

away from any other control device. Bengsen at al (2012) determined a similar maximum

distance between control devices of 770 metres.


Figure 3) Home ranges and GPS points of 14 collared feral cats


5. Cage trapping trial

5.1 Methods

Cage trapping was conducted in spring and autumn using wire cage traps of dimensions 65

x 26 x 26 centimetres (cm) with a flat treadle plate (Figure 4). A combination of chicken

wings, fish and kangaroo meat were used as bait which were suspended from the roof of the

trap by a wire hook. All cage traps were surrounded with a line of Coopex™ insecticide to

minimise the risk of baits attracting ants and captured animals subsequently being injured.

Traps were covered with hessian bags to provide shade for captured animals.

Traps were placed at random within the IMZ, with a minimum distance of 100 metres

between traps. The placement of traps, number of traps used and number of nights

deployed all varied during each of the four trapping sessions (see Table 3).

Traps were checked each morning and re-baited as necessary. Any feral cats caught were

radio-collared and released.

A Recoynx™ infra-red HC600 motion-activated camera was placed at a height of 30 cm or

greater on a wooden stake at a distance of between two and three metres from the entrance

of the trap. At the completion of the trapping trial, all camera images were downloaded and

processed by trained staff.

Figure 4) Feral cat entering a cage trap.


Table 3) Number of trap nights used during the cage trapping trials

Season Session 1 Session 2 Session 3 Trap nights

Spring

(November 2016)

Number of traps 21 27 25 309

Number of nights 6 4 3

Autumn

(May 2017)

Number of traps 36 - - 144

Number of nights 4 - -

5.2 Results

During the trial 17 feral cats were captured in cage traps. Nine of those cats already had

radio collars, indicating that they had been previously captured either during this trial or as

part of other activities carried out by this program.

Trapping effectiveness was expressed in two ways:

1. Catch per unit effort, which was calculated by dividing the number of cat captures by

total trapping effort (expressed in trap nights, where trap nights = no. traps x no. nights

traps are set).

2. Catch rate per encounter, which was calculated as the percentage of direct encounters

between cats and traps that resulted in a successful capture. The numbers of encounters

between feral cats and cage traps were obtained from camera trapping data.

Catch per unit effort ranged from 3.5% in autumn (five cats captured during 144 trap nights)

to 3.9% in spring (12 cats captured during 309 trap nights) (Table 4). Catch rate per

encounter was 42.9% in spring (12 cats captured out of 28 encounters), but only 15.6% in

autumn (five cats captured out of 32 encounters) (Table 4). In both spring and autumn at

least 50% of cats captured were recaptures.

Table 4) Cage trapping effectiveness

Measure of effectiveness Spring Autumn

Trapping success

New cats captured 6 2

Recaptures 6 3

Not captured 16 27

Catch per unit effort New cats only 1.6% 1.4%

All cats 3.9% 3.5%

Catch rate per encounter All cats 42.9% 16.1%


5.3 Discussion

These results show that in the IMZ (and similar landscapes) cage traps can be an effective

feral cat control tool.

Our findings are similar to those of Southgate and Masters (2011) who caught nine cats in

370 trap nights (CPUE = 2.4%) and Rowley and Masters (2013) who caught 15 cats in 325

trap nights (CPUE = 4.6%). Both of these studies were carried out in areas that overlap with

much of the IMZ.

Other studies of cage trapping on Kangaroo Island include Paton (2003) who reported

capturing 72 cats in 2792 trap nights (CPUE = 2.6%) at Murray Lagoon, and Hodgens (2019)

who reported capturing 21 feral cats over 148 trap nights (CPUE = 14.2%) on the Dudley

Peninsula. However, this last study was mainly conducted within an area of actively farmed

agricultural land where the density of feral cats may be higher than in the IMZ, which may

contribute to the higher success rate.

The catch rate per encounter was much higher in spring than in autumn, however this could

be explained by the fact that there was also a correspondingly higher percentage of

uncollared cats encountered in spring (46.4%, 13 out of 28 encounters) than in autumn

(18.8%, 6 out of 32 encounters). This may indicate that cats that had previously been caught

in traps and released were less likely to be caught again.


6. Baiting trial

6.1 Methods

Four separate surveys were conducted using non-toxic Eradicat® baits to assess target and

non-target bait uptake in different seasons. The Eradicat® baits were supplied by the

Western Australian Department of Parks and Wildlife and were meat-based, chipolata-sized

sausage shaped baits made up of 70% kangaroo mincemeat, 20% chicken fat and 10%

digest and flavour enhancers. Frozen baits were thawed the day before baiting and then

‘sweated’ by placing them in the full sun for half a day. This process allowed the fats and oils

inside the bait to permeate through the skin to help attract feral cats. Baits were also sprayed

with a solution of diluted Coopex™ powder to reduce bait degradation from ant attacks.

Surveys were conducted at 46 sites located within the IMZ during September 2016, May

2017, June 2017 and July 2017.

At the commencement of each survey, a single Eradicat® bait was placed at each site. A

Recoynx™ infra-red HC600 motion-activated camera was placed at a height of 30 cm or

greater on a wooden stake at a distance of between two and three metres from the bait. At

the completion of the survey, all camera images were downloaded and the fate of each bait

was recorded by trained staff.

Baits were classified as being ’consumed’ if they were clearly ingested by an animal, or were

picked up in the mouth or beak of an animal before disappearing (Figure 6).

Figure 5) Non-toxic Eradicat® bait in front of a Reconyx™ HC600 camera.


Figure 6) Feral cat consuming a non-toxic Eradicat® bait

6.2 Results

Data could not be collected on 15 baits as either the cameras were placed in a position

where the bait was not visible in the frame (14 baits), or the images were lost before they

could be processed (one bait). These baits have been excluded from the results.

Of the remaining 169 baits, nine were still in position at the end of the survey and were

recorded as not eaten (5.3%). 27 baits were recorded as being consumed by feral cats

(16.0%), 34 by ravens (20.1%) and 73 baits disappeared without the camera recording what

had consumed them (43.2%) (Table 5).

In all four survey months, more baits were consumed by non-target species than by feral

cats.

There were 41 encounters between feral cats and baits over the four surveys. In 27 of these

encounters the cat was confirmed to have consumed the bait (65.9%) (Table 6).

There was no significant difference between survey months in the proportion of feral cats

encountering baits that consumed them (chi-squared = 3.38, P = 0.34). Nor was there a

significant difference between surveys in the proportion of feral cats consuming baits

compared to the number of baits laid out (chi-squared = 2.06, P = 0.56).


Table 5) The fate of each of the 169 baits recorded during the trial

Survey month

Common name Scientific name Sep 16 May 17 Jun 17 Jul 17 Total

Unknown (bait disappeared) - 12 25 18 18 73

Raven sp. Corvus sp. 25 2 3 4 34

Feral cat Felis catus 6 5 5 11 27

Common brushtail possum Trichosurus vulpecula - 2 8 2 12

House mouse Mus musculus - 2 4 4 10

Not eaten - 2 3 2 2 9

Grey currawong Strepera versicolor - - 1 - 1

Australian magpie Gymnorhina tibicen 1 - - - 1

Bush rat Rattus fuscipes - - - 1 1

Domestic dog Canis lupus familiaris - - - 1 1

Total baits 46 39 41 43 169

Table 6) Consumption of baits by feral cats

Survey month Cats that

encountered a bait

Cats that

consumed the bait

Cats that did not

consume the bait

Sep 2016 8 6 (75.0%) 2 (25.0%)

May 2017 11 5 (45.5%) 6 (54.5%)

Jun 2017 8 5 (62.5%) 3 (37.5%)

Jul 2017 14 11 (78.6%) 3 (21.4%)

Total feral cats 41 27 (65.9%) 14 (34.1%)


Figure 7) Chart showing the fate of all 184 baits deployed during this trial

6.3 Discussion

The results of this non-toxic baiting trial suggest that in the IMZ (and similar landscapes)

toxic baiting could remove a significant proportion of feral cats from the population, but

there are likely to be non-target impacts.

In all four surveys more baits were consumed by non-target species than by feral cats. In

total 60 baits (35.5%) were consumed by non-target species and a further 73 baits (43.2%)

were consumed by an unknown species. Only 27 baits (16.0%) were known to be consumed

by feral cats.

Toxicological studies suggest that many animal species native to Kangaroo Island are likely

to have a low tolerance to 1080 (the toxin used in the Eradicat® baits) (see Table 7).

During this trial ravens, common brushtail possums, bush rats, grey currawongs and

Australian magpies were all observed consuming more than the median lethal dose of 1080

for those species. These results match those of Hohnen et al (forthcoming) who concluded

that Australian ravens, common brushtail possums and bush rats are likely to be severely

negatively affected by the use of this bait.

The results of the bait trials conducted in this study are also similar to the previous bait study

on Kangaroo Island by Denny (2009), who used track observations on sand plots to measure

bait consumption. That study concluded that 10.8% of baits were consumed by feral cats,

33.1% were consumed by non-target species and 56.1% by an unknown species.

Interestingly, Denny (2009) recorded that 6.1% of baits were taken by tammar wallabies

(Macropus eugenii) and 2.1% by the Kangaroo Island kangaroo (Macropus fuliginosus ssp.

0

5

10

15

20

25

Unknown(bait

disappeared)

Raven sp. Feral cat Unknown(missed by

camera)

Commonbrushtailpossum

Housemouse

Not eaten Greycurrawong

Domesticdog

Unknown(photos lost)

Bush rat Australianmagpie

Nu

mb

er o

f b

aits

Fate of bait

Sep May Jun Jul


fugilinosus), however our study did not detect any baits being consumed by macropods.

Hohnen el al (forthcoming) also did not record macropods consuming any baits.

Table 7) Tolerance of native animals observed consuming baits to 1080 (from APVMA 2008)

Common name Scientific name Weight range

(kg)

LD50

(mg kg-1)

Number of

baits for LD501

Australian magpie Gymnorhina tibicen 0.25-0.38 9.93 0.6-0.8

Bush rat Rattus fuscipes 0.13-0.17 1.13 0.03-0.04

Common brushtail possum Trichosurus vulpecula 1.4–3.8 0.47–0.79 0.1-0.7

Domestic dog Canis lupus familiaris 6-15 0.07 0.1-0.2

Feral cat Felis catus 1.0-4.0 0.4 0.1-0.4

Grey currawong2 Strepera versicolor 0.25-0.36 13.09 0.7-1.0

House mouse Mus musculus 0.02 8.3 0.04

Raven sp. Corvus sp. 0.46-0.75 3.1-5.1 0.3-0.9

1 Based on a single Eradicat® bait containing 4.5 mg of 1080 (Natural Resources Kangaroo

Island 2019) 2 Figures quoted are for the similar pied currawong (Strepera graculina)

Denny (2009) also recorded that 5.1% of baits were taken by heath goannas (Varanus

rosenbergi), with baits taken in October and November, but none in March. Hohnen et al

(forthcoming) also recorded baits being consumed by heath goannas in November but not

in August. Our results also concur with this evidence that impacts to heath goannas could be

minimised if baiting only occurs during the cooler months when they are less active.

Using baits with toxins contained in an encapsulated pellet (also known as a hard shell

delivery vehicle, or HSDV) could reduce the predicted non-target impacts. However, De Tores

et al (2011) recorded bandicoots and varanids consuming baits and encapsulated pellets in

both captive and field trials, and Buckmaster et al (2014) assessed 47 species of native

vertebrates as likely to ingest HSDVs, including some bandicoot, dunnart and currawong

species.

It is also possible that the Curiosity® bait may be a useful alternative to Eradicat®. This

encapsulated bait contains 78 mg of the toxin PAPP (para-aminopropiophenone) and some

native animals have a higher tolerance to this toxin than to 1080, e.g. the LD50 values for

PAPP are 500mg/kg for brushtail possums, 697 mg/kg for bush rats and 1387 mg/kg for

Australian magpies (APVMA 2015). However, a study by Johnston et al (2014) at Roxby

Downs observed a 50% decrease in the number of Australian ravens after baiting with

Curiosity®. It should be acknowledged that it was not possible to determine whether this

decline was actually linked to the birds consuming baits, or other coincidental factors.

The potential for non-target impacts will need to be given careful consideration before

conducting a widespread baiting program on Kangaroo Island.


7. Conclusions

The aims of Phase One of the FCEP were to:

1. Determine feral cat density within the study area.

2. Investigate the movement patterns of feral cats and their home range sizes.

3. Determine the effectiveness of a range of feral cat control methods.

4. Provide recommendations for Phase Two of the FCEP.

7.1 Density

An accurate figure for feral cat density within the IMZ could not be calculated from the data

collected during this project.

7.2 Movement patterns and home range sizes

Home range sizes for feral cats is variable, ranging from less than 2 km2 to over 10 km2. The

home ranges of multiple cats can overlap with each other spatially, but this study did not

determine whether they can also overlap temporally. Male cats appear to be more likely than

females to venture outside of their home range.

7.3 Control methods

This project undertook field trials to evaluate the effectiveness of cage trapping and non-

toxic baiting as techniques for feral cat control on Kangaroo Island.

Cage trapping

Cage trapping can be an effective cat control technique and should be included in the suite

of control tools for any eradication effort. Cage trapping is also a valuable community

engagement activity and can be undertaken by landholders with minimal training. However,

cage trapping is generally more effective when carried out by skilled operators. Cage traps

can be used at any time of year with low non-target impacts as any animals caught can easily

be released unharmed.

Baiting

Broad-scale toxic baiting may also be an effective cat control technique, particularly for

remote and inaccessible areas such as national parks, however there are legitimate concerns

about the level of non-target bait consumption. It may be possible to increase the

percentage uptake of baits by feral cats and reduce the impacts on non-target species

through careful planning regarding the spatial and temporal deployment of baits (for

example by only baiting in winter when heath goannas are in lower state of metabolic

activity). However, this approach may not be able to remove the risk completely, particularly

to abundant and widespread species such as ravens and the common brushtail possum.


7.4 Key Recommendations for Phase Two

1. Establish a camera trap array across the Dudley Peninsula to allow feral cat abundance to

be monitored in a variety of habitats and landscapes. Smaller-scale camera trap arrays

may also be established to monitor feral cat density at targeted sites. The information

collected from these arrays will allow the program to track the effectiveness of future

feral cat eradication activities.

2. Place control devices used during eradication operations no more than 690 metres away

from any other control device. This will ensure that all feral cats can potentially encounter

at least one control device.

3. Deploy cage traps under the guidance of skilled operators in order to maximise their

efficiency in capturing feral cats.

4. Undertake trials on the effectiveness of using thermal imaging rifle scopes and binoculars

for shooting feral cats at night. These proved to be useful tools during this project and

should be investigated further.

5. Investigate the effectiveness of using wildlife detector dogs to assist with eradication

activities.

6. Consider the following points in relation to carrying out toxic baiting trials:

a. The type of bait and toxin to be deployed

b. The time of year baiting is carried out

c. The spacing of baits and frequency of any repeat deployments

d. How to measure baiting effectiveness and impacts on key non-target species


8. References

APVMA. 2008. Review findings for sodium monofluoroacetate: The reconsideration of

registrations of products containing sodium monofluoroacetate and approvals of their

associated labels. Australian Pesticides and Veterinary Medicines Authority, Canberra.

APVMA. 2015. Public release summary on the evaluation of the new Active 4-

aminopropiophenone (also known as para-aminopropiophenone(PAPP)) in the products

Foxecute Fox Bait & PAPP Wild Dog Bait. Australian Pesticides and Veterinary Medicines

Authority, Canberra.

Bengsen A, Butler J and Masters P. 2012. Applying home-range and landscape-use data to

design effective feral-cat control programs. Wildlife Research, 39(3), 258–265.

Buckmaster T, Dickman CR and Johnston MJ. 2014. Assessing Risks to Non-Target Species

during Poison Baiting Programs for Feral Cats. PLoS ONE 9(9): e107788.

Calenge C. 2006. The package “adehabitat” for the R software: A tool for the analysis of

space and habitat use by animals. Ecological Modelling, 197, 516-519.

De Tores PJ, Sutherland DR, Clarke JR, Hill RF, Garretson SW, Bloomfield L, Strümpher L, Glen

AS, Cruz J. 2011. Assessment of risks to non-target species from an encapsulated toxin in a

bait proposed for control of feral cats. Wildlife Research, 38, 39–50.

Denny E. 2009. Feral Cat Bait Uptake Trials. 2. Kangaroo Island. Report to the Invasive

Animals Cooperative Research Centre.

Hodgens P. 2019. Felixer vs felis report. Report to the Kangaroo Island Natural Resources

Management Board.

Hohnen R, Murphy B, Legge S, Dickman C, & Woinarski J. (forthcoming). Uptake of “Eradicat”

feral cat baits by non-target species on Kangaroo Island. Wildlife Research.

Johnston M, Bould L, O’Donoghue M, Holdsworth M, Marmion P, Bilney R, Reside AE,

Caldwell D, Gaborov R, Gentles T. 2014. Field efficacy of the Curiosity® bait for management

of a feral cat population at Roxby Downs, South Australia. Arthur Rylah Institute for

Environmental Research Technical Report Series No. 253.

Natural Resources Kangaroo Island. 2015. Feral cat eradication on Kangaroo Island 2015–

2030 Prospectus. Natural Resources Kangaroo Island.

Natural Resources Kangaroo Island. 2019. Kangaroo Island Feral Cat Eradication Program

1080 FAQs. Natural Resources Kangaroo Island.

Paton D. 2003. Developing a community-based feral cat control program for Kangaroo

Island. In ‘Proceedings of the Kangaroo Island Rotary Club Seminar’. Unpublished.

R Core Team. 2018. R: A language and environment for statistical computing. R Foundation

for Statistical Computing, Vienna, Austria.


Rowley D and Masters P. 2013. Estimating the impact of intensive community trapping of

cats on population density in the Pelican Lagoon and Island Beach area on Kangaroo Island

during autumn 2013. Report to the Kangaroo Island Natural Resources Management Board.

Southgate R and Masters P. 2011. Co-ordinated community management of feral cats in the

Island Beach- Pelican Lagoon area on Kangaroo Island: spring 2011. Report to the Kangaroo

Island Natural Resources Management Board.


Appendix A

Home range curves of GPS collared cats showing proximity to asymptote.


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