Eradication project of invasive alien mongooses in Japan

- Okinawa and Amami-oshima Island-

Office for Alien Species Management, Wildlife Division,

Nature Conservation Bureau,

Ministry of the environment

Masato Morikawa

1

Okinawa

Amami-oshima

Tokyo

Kagoshima

Taiwan

Okinawa Island (1,208 km2)

Population: 1,200,000

Amami-oshima

Island (712 km2)

Population: 70,000

Ryukyu Archipelago - one of biodiversity hot spots of the world

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Ryukyu Archipelago - one of biodiversity hot spots of the world

• Biogeographically, border of Palearctic and Oriental region.

• Isolated from the continent about 2 - 1.7 million years ago.

c.f. Mainland Japan : isolated about 10 000 – 20 000 years ago.

• Many endemic species inhabit with limited predator species

Kyusyu

Korea

Taiwan

Watase line

Islands of poisonous snake, habu 3

Amami-group

Okinawa-group

Miyako-group Yaeyama-group

Iriomote Is. Ishigaki Is.

Miyako Is.

Okinawa Is.

Amami-oshima Is.

Tokunoshima Is.

Native wildlife in the Ryukyus evolved in the absence of predatory mammals

Amami rabbit (Pentalagus furnessi)

Amami woodcock (Scolopax mira)

Amami thrush (Zoothera dauma major)

Okinawa rail (Gallirallus okinawae)

Yambaru long-armed scarab beetle

(Cheirotonus jambar)

Okinawa woodpecker (Dendrocopos noguchii)

Iriomote cat (Prionailurus bengalensis

iriomotensis)

Crested Serpent Eagle (Spilornis cheela perplexus)

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Small Indian Mongoose (Herpestes auropunctatus)

• A small, slim-bodied predator native to areas from Iran, through India to Myanmar, VietNam.

• It has been introduced to many islands to control rats, particularly in sugar cane fields of tropics.

• The mongoose has had a major impact on native species in the areas where it has been introduced.

100 of the worst invasive alien species by ISSG, IUCN

Small Indian mongoose

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More than 70 islands/areas introduced

(Hays & Conant, 2007) 6

released in 1910

（1978年）

（2004年）

O kinaw a Is.

1910: First introduction to Japan

• Dr. Watase, the famous biologist in Japan was advised by foreign scientists to import mongooses to control poisonous snake Habu and harmful black rat

• Released around southern part of Okinawa and settled and spread gradually

• 1990s: Expand to Yamabaru region(northern Okinawa) , the hotspot of wildlife

• Mongoose Control measure launched by Okinawa Prefectural Government & MOE launched from 2000

(1,206km2)

1990 1978

2004

(300km2)

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Starting control efforts

• In 2000, the Okinawa Prefectural Government began cull efforts.

• In 2005, control efforts began with the enforcement of

the Invasive Alien Species Act.

• The mongoose population continued to expand until 2006, causing the Okinawa rail population to retreat.

• Mongoose proof fence installed in 2006 in SF line to prevent mongooses from spreading north.

FY 2003 FY 2000 FY 2006 8

SF line

Outline of control measures • Control initiatives began with cage-type live traps, which required daily

checking. Trappers installed traps along logging roads.

• The introduction of tube-type kill traps for which checking frequency can

be set as desired (usually every two to four weeks) and the use of kill traps

and live traps as required brought about a drastic increase in the number of

traps managed.

• Trappers began related work in forests in FY 2007.

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2000 2001 2002 2003 2004 2005 2006 2007 2008 2009 2010 2011 2012 2013Live trap

Forest workKill trapSensor camerasSniffer dogsNative species monitoring

Preventing damage of indiscriminate capture • Kill traps were first introduced in 2003 • Deploy endemic rats are absent and/or

in low density.

■ Live trap …Everyday checking is necessary …Used in habitat of endangered native species ■ Kill trap (Pipe- trap) …Efficient (Lightweight, Set for 2-4 weeks) …Birds : discriminable Rats : indiscriminable

Simulation and trial to decide trap shape

for preventing endemic birds

Ryukyu long-

haired rat

（Diplothrix legata）

Amami spiny rat

（Tokudaia

osimensis）

Amami jay 10

Okinawa rail trigger

Changes in capture status Distribution of mongooses have decreased

2006 2007 2008 2009 Location of trap installation Location of trap installation Location of trap installation Location of trap installation

11

2010 2011 2012 Location of trap installation Location of trap installation Location of trap installation

Capture number of mongooses Capture number of mongooses Capture number of mongooses Capture number of mongooses

Capture number of

mongooses

Capture number of

mongooses Capture number of

mongooses

12

208

284

520 543573 549

619560

396

230

255202

0

500,000

1,000,000

1,500,000

2,000,000

2,500,000

0

200

400

600

800

1,000

Mongooses

Trap-days

0.16

0.27

0.43

0.29

0.20 0.19

0.17

0.06 0.03

0.02 0.0160.014

0.000

0.100

0.200

0.300

0.400

0.500

CPUE (C/100TD)

Okinawa

CPUE(Mongooses/100Trap-days)

• Since the Yambaru Mongoose Busters started its activities, there has been a

drastic increase in the total number of traps (see the line graph). The total

number of trap days has kept around 1.5 million every year since 2011. The

number of mongooses caught (see the bar graph) has shown a declining

trend since 2008, and been a significant drop in the number in recent years.

• CPUE, an indicator of mongoose population size, has continued to decrease.

Changes in capture status Mongooses have steadily decreased

1979: Introduction into Amami from Okinawa Island

released in 1979

（2004年）

（1990年）

A m am i-oshim a Is.

（2004年）

(712 km2)

• There are few records about introduction into Amami

• Mongooses were brought in from Okinawa Island (Sekiguchi et.al.,2001)

• Mongooses successfully settled on Amami and expanded their distribution

• Damages on farming and poultry gradually appeared from 1983

• Some research by Amami Mammalogical Society from 1989

• Pest control by local government began from 1993

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Strong negative impacts on native vertebrates Partial extinction of mammals and amphibians in range of mongooses

Amami Wildlife Conservation Center from 2000 to 2006

Amami rabbit

Ryukyu long-haired rat

Amami spiny rat

Amami Ishikawa s frog

Otton frog

Amami tip-nosed frog

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：distribution of native vertebrates ：core area of range of mongooses

1993-: Pest control by local government

• Pest animal that causes harm to crops and chicks

• Local government launched control to reduce damages of crops

• Licensed trapper were paid JPY 2,200 for a mongoose

• 8,234 mongooses were captured in seven years (1993-1999)

• Most of them captured around the center of distribution, high density area

ⒸAmami city

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2000-2004: Control program by bounty trapper

• At the beginning, mongooses were live trapped by one hundred bounty trappers

• To keep incentive to trap, bounty increased from JPY 2,200 (2000) to JPY 4,000 (2001-02) and JPY 5,000 (2003-04)

• Trapping data of bounty trappers were collected with using standard grid square (about 1 km2 mesh)

• A small number of trappers were employed to set traps at low density area and in bushes. 1 trapper in 2002, 4 in 2003, and 6 in 2004

• 14,558 mongooses were caught in this five year trapping 2000-2004

Seminar for bounty trapper

Live trap

1 4 6 12

0

20

40

60

80

100

120

2000 2001 2002 2003 2004 2005

Bounty trapper

Full time trapper

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2005- Organizing Amami Mongoose Busters (AMB)

• Invasive Alien Species Act was enforced in 2005 • MOE launched a mongoose eradication project,

hiring trapping experts, “Amami Mongoose Busters (AMB)”.

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0

20

40

60

80

100

120Bounty trapper

Full time trapper, AMB

2013: AMB and trained sniffer dogs

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32,357 mongooses caught in 20 years

20

0

500

1,000

1,500

2,000

2,500

3,000

3,500

4,000

4,500

19

92

19

93

19

94

19

95

19

96

19

97

19

98

19

99

20

00

20

01

20

02

20

03

20

04

20

05

20

06

20

07

20

08

20

09

20

10

20

11

20

12

Project by MOE

Pest control

10,351 mongooses by pest control

22,006 mongooses by MOE project

Trapping data set

AMB

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CPUE (Capture/1000trap-days) distribution

FY2001

22

2001 2002 2003

2004 2005 2006

2007 2008 2009

CPUE (Capture/1000trap-days) distribution

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2010 2011

2012

0.01

0.10

1.00

10.00

100.00

20

01

20

02

20

03

20

04

20

05

20

06

20

07

20

08

20

09

20

10

20

11

20

12

Log_

CP

UE

(C/1

00

0TD

)

Year

Live trap Kill trap Modified kill trap

37,000 traps are deployed

FY2012: 197 mongooses captured

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In FY2012, 179 mongooses were caught with 2.26 million trap-days. 18 mongooses were caught with sniffer dogs and handler.

In FY2012, 179 mongooses were caught with 2.26 million trap-days. 18 mongooses were caught with sniffer dogs and handler.

1980 1990 2000 2010

個体数

100

1000

推定個体数捕獲数

10

00

0

Log 1

0 (P

op

ula

tio

n s

ize)

year

Estimated population Number of capture

Abundance dynamics of mongooses

Hierarchical Bayes Model

25

Fukasawa et al., 2013a Proc. R. Soc. B

Year

CP

UE(

anim

als

/10

00

trap

-day

s)

05

10

15

2002:2009

ycp

ue.m

on

(A) Small Indian mongoose

05

10

2002:2009

ycp

ue.r

at.

dis

(B) Black rat

05

10

15

2002:2009

ycp

ue.t

og

e.n

at

(C) Amami Spiny rat

2002 2004 2006 2008

01

2

ycp

ue.k

en

ag

a.n

at

(D) Ryukyu long-haired rat

05

10

15

2002:2009

ycp

ue.m

on

(A) Small Indian mongoose

05

10

2002:2009

ycp

ue.r

at.

dis

(B) Black rat

05

10

15

2002:2009

ycp

ue.t

og

e.n

at

(C) Amami Spiny rat

2002 2004 2006 2008

01

2

ycp

ue.k

en

ag

a.n

at

(D) Ryukyu long-haired rat

05

10

15

2002:2009

ycp

ue.m

on

(A) Small Indian mongoose

05

10

2002:2009

ycp

ue.r

at.

dis

(B) Black rat

05

10

15

2002:2009

ycp

ue.t

og

e.n

at

(C) Amami Spiny rat

2002 2004 2006 2008

01

2

ycp

ue.k

en

ag

a.n

at

(D) Ryukyu long-haired rat

Recovery of native species 1

26

Alien Native

Figure 2. Temporal changes in catch per unit effort . For the rat species, the solid and dashed lines indicate the areas of mild (habitat alteration index, HAI<0) and intensive (HAI >0) habitat alteration, respectively.

Watari et al., 2013 Ecology and Evolution Recovery of native species 2

Scientists surveyed the population densities along logging road of four endangered species threatened by the mongoose.

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Amami rabbit Amami tip-nosed frog

Otton frog

Amami Ishikawa’s frog

Figure 3. Temporal changes in numbers of four species observed per site per survey (mean SE).

Fukasawa et al., 2013b J. Applied Ecology

Probability of eradication success

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• This simulation shows the current capture efforts of 2010 is the most cost-effective way to eradicate mongooses in this island.

The eradication success might be feasible if eradication action same capture efforts of 2010 is continued over the next decade. • However, we think that the most difficult point of eradication of mongooses is one final push (Trapping final 10 mongooses ).

Therefore we are also considering alternative measure.

― ― ― ― ― ― ― ― ― ― ― ― ― ― ― ― ― ― ― ― ― ― ― ― ― ― ― ― ― ― ― ― ― ― ― ― ― ― ― ― ― ― ― ― ― ― ― ― ― ― ― ― ― ― ― ― ― ― ― ― ― ― ― ― ― ― ― ― ― ― ― ― ― ― ― ― ― ― ― ― ― ― ― ― ― ― ― ― ― ― ― ― ― ― ― ― ― ― ― ― ― ― ― ― ― ― ― ― ― ― ― ― ― ― ― ― ― ― ― ― ― ― ― ― ― ― ― ― ― ― ― ― ― ― ― ― ― ― ― ― ― ― ― ― ― ― ― ― ― ― ― ― ― ― ― ― ― ― ― ― ― ― ― ― ― ― ― ― ― ― ― ― ― ― ― ― ― ― ― ― ― ― ― ― ― ― ― ― ― ― ― ― ― ― ― ― ― ― ― ―

0.0 0.2 0.4 0.6 0.8 1.02020

2030

2040

2050

4.5

5.05.5

6.06.5

7.0

0.00.20.40.60.8

1.0

The eradication feasibility of mongooses was estimated using trapping data. (see black circle which indicate eradication feasibility.)

• New ten year mongoose eradication plan was settled on from FY2013 to 2022.

• The challenges are to eradicate small number of mongooses scattered in a large area, and to ensure that no mongoose survives in every area, with using sniffer dogs, camera traps and hair traps.

Eradication action plan by 2022

Monitoring area

Priority area

29 http://kyushu.env.go.jp/naha/wildlife/data/gairai/boujyo/130425b.html

Education & Awareness Pamphlet for the mongoose eradication measure

http://kyushu.env.go.jp/naha/wildlife/data/gairai/boujyo/131017a.pdf 30

Thank you for your attention

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