Eradication project of invasive alien mongooses in Japan - Okinawa and Amami-oshima Island-Masato Morikawa
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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
Ryukyu Archipelago
- one of biodiversity hot spots of the world
Tokyo Amami-oshima
Island (712 km2)
Population: 70,000
Kagoshima
Amami-oshima
Okinawa
Okinawa Island (1,208 km2)
Taiwan Population: 1,200,000
2
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
Korea
Kyusyu
Watase line
Taiwan
Islands of poisonous snake, habu 3
Native wildlife in the Ryukyus evolved in the
absence of predatory mammals
Amami-group
Amami-oshima Is.
Tokunoshima Is.
Iriomote cat Amami rabbit
(Prionailurus bengalensis (Pentalagus furnessi)
iriomotensis) Okinawa-group
Crested Serpent Eagle Amami woodcock
(Spilornis cheela perplexus) Okinawa Is. (Scolopax mira)
Yaeyama-group
Miyako-group
Miyako Is.
Ishigaki Is.
Iriomote Is.
Yambaru long-armed
Okinawa woodpecker Okinawa rail Amami thrush
scarab beetle
(Dendrocopos noguchii) (Gallirallus okinawae) (Zoothera dauma major)
(Cheirotonus jambar)
4
Small Indian Mongoose
(Herpestes auropunctatus)
• A small, slim-bodied predator native
to areas from Iran, through India to
Myanmar, VietNam. Small Indian mongoose
• 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.
5
100 of the worst invasive alien species by ISSG, IUCN
More than 70 islands/areas introduced
(Hays & Conant, 2007)
6
1910: First introduction to Japan
(300km2)
• Dr. Watase, the famous biologist
（2004年）
2004
in Japan was advised by foreign
scientists to import mongooses
to control poisonous snake Habu
and harmful black rat
（1978年）
1978
• Released around southern part 1990
of Okinawa and settled and
spread gradually
• 1990s: Expand to Yamabaru
region(northern Okinawa) , the O kinaw a Is.
(1,206km2)
hotspot of wildlife
• Mongoose Control measure
launched by Okinawa Prefectural
Government & MOE launched
from 2000
released in 1910 7
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.
SF line
FY 2000 FY 2003 FY 2006 8
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.
2000 2001 2002 2003 2004 2005 2006 2007 2008 2009 2010 2011 2012 2013
Live trap
Forest work
Kill trap
Sensor cameras
Sniffer dogs
Native species monitoring 9
Preventing damage of indiscriminate capture
• Kill traps were first introduced in 2003
• Deploy endemic rats are absent and/or
in low density.
Amami spiny rat
（Tokudaia
■ Live trap osimensis）
…Everyday checking is necessary
…Used in habitat of endangered native species Ryukyu long-
haired rat
（Diplothrix legata）
■ Kill trap (Pipe- trap)
…Efficient (Lightweight, Set for 2-4 weeks)
…Birds : discriminable
Rats : indiscriminable
Okinawa rail
trigger
Simulation and trial to decide trap shape
Amami 10
jay
for preventing endemic birdsChanges in capture status
Distribution of mongooses have decreased
Capture number of mongooses Capture number of mongooses Capture number of mongooses Capture number of mongooses
2006 2007 2008 2009
Location of trap installation Location of trap installation Location of trap installation Location of trap installation
Capture number of Capture number of Capture number of
mongooses mongooses mongooses
2010 2011 2012
Location of trap installation Location of trap installation Location of trap installation
11Changes in capture status
Mongooses have steadily decreased
1,000 2,500,000 0.500
0.43
Mongooses CPUE(Mongooses/100Trap-days)
CPUE (C/100TD)
800 2,000,000 0.400
Trap-days
619
573 0.29
600 549 560 1,500,000 0.27
520 543 0.300
396
0.20
0.19
Okinawa
400 1,000,000 0.200 0.16 0.17
284
255
208 230 202
200 500,000 0.100 0.06
0.03 0.014
0.02 0.016
0 0 0.000
• 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.
121979: Introduction into Amami
from Okinawa Island
• There are few records about
introduction into Amami
• Mongooses were brought in from
Okinawa Island (Sekiguchi released in 1979
（2004年）
et.al.,2001)
• Mongooses successfully settled on （1990年）
Amami and expanded their （2004年）
distribution
• Damages on farming and poultry
gradually appeared from 1983
• Some research by Amami
Mammalogical Society from 1989
A m am i-oshim a Is.
• Pest control by local government (712 km2)
began from 1993
14Strong negative impacts on native vertebrates
Partial extinction of mammals and amphibians in range of mongooses
：distribution of native vertebrates ：core area of range of mongooses
Amami rabbit Amami Ishikawa s frog
Ryukyu long-haired rat
Otton frog
Amami spiny rat Amami tip-nosed frog
15
Amami Wildlife Conservation Center from 2000 to 20061993-: 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 ⒸAmami city
seven years (1993-1999)
• Most of them captured around the
center of distribution, high density
area
162000-2004: Control program by bounty trapper
Live trap
• 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)
Seminar for
and JPY 5,000 (2003-04) bounty trapper
• 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 120 Bounty trapper
• 14,558 mongooses were caught in this five 100
Full time trapper
year trapping 2000-2004 80
60
40
20 12
4 6
1
0
17
2000 2001 2002 2003 2004 20052005- 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)”.
120
Bounty trapper
100
Full time trapper, AMB
80
60
40
20
0
182013: AMB and trained sniffer dogs
1932,357 mongooses caught in 20 years
4,500
Project by MOE
Pest control
4,000
Trapping data set
3,500
3,000
AMB
2,500
2,000
1,500
1,000
500
0
1992
1993
1994
1995
1996
1997
1998
1999
2000
2001
2002
2003
2004
2005
2006
2007
2008
2009
2010
2011
2012
10,351 mongooses by pest control
22,006 mongooses by MOE project
20CPUE (Capture/1000trap-days) distribution
FY2001
21CPUE (Capture/1000trap-days) distribution
2001 2002 2003
2004 2005 2006
2007 2008 2009
222012
2010
Log_CPUE (C/1000TD)
10.00
100.00
0.01
0.10
1.00
2001
2002
2003
2004
2005
2011
2006
Year
2007
2008
2009
2010
2011
2012
23FY2012: 197 mongooses captured
In37,000
FY2012, 179are
traps mongooses
deployed were caught
with 2.26 million trap-days. 18 mongooses
were caught with sniffer dogs and handler.
Live trap
Kill trap
Modified kill trap
24Abundance dynamics of mongooses
10000
Estimated
推定個体数 population
Number
捕獲数 of capture
(Population size)
1000
Log10個体数
100
Hierarchical Bayes Model
1980 1990 2000 2010
year 25(B) Black rat
10
10
ycpue.rat.dis
ycpue.rat.dis
2002:2009 2002:2009
Fukasawa et al., 2013a
Recovery of native species 1 Proc. R. Soc. B
5
5
0 Alien Native
0
(A) Amami
(C) Small Indian
Spinymongoose
rat (C) Amami Spiny rat
15
10 15
15
ycpue.toge.nat
ycpue.toge.nat
2002:2009
ycpue.mon
2002:2009
CPUE(animals /1000trap-days)
10
10
55
5
00
0
(D) Ryukyu
(B) Black ratlong-haired rat (D) Ryukyu long-haired rat
ycpue.kenaga.nat
ycpue.kenaga.nat
10
2
2
ycpue.rat.dis
2002:2009
2002:2009 2002:2009
51
1
00
0
(C) Amami
2002 2004 Spiny
2006rat 2008 2002 2004 2006 2008
15
cpue.toge.nat
Figure 2. Temporal changes in catch2002:2009
per unit effort .
For the rat species, the solid and dashed lines indicate Year
10
the areas of mild (habitat alteration index, HAI0) habitat alteration, respectively.Watari et al., 2013
Recovery of native species 2 Ecology and Evolution
Scientists surveyed the population densities along logging road of four endangered
species threatened by the mongoose.
Amami rabbit Amami tip-
nosed frog
Otton frog
Amami
Ishikawa’s
frog
Figure 3. Temporal changes in numbers of four species 27
observed per site per survey (mean SE).Probability of eradication success
• 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.
Fukasawa et al., 2013b
J. Applied Ecology
The eradication feasibility of
1.0 mongooses was estimated
0.8 using trapping data. (see
0.6 black circle which indicate
0.4
0.2
eradication feasibility.)
0.0
7.0 2050
6.5 2040
6.0 2030
5.5 0.0 0.2 0.4 0.6 0.8 1.0
5.0 2020
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4.5Eradication action plan by 2022
• New ten year mongoose Monitoring area
eradication plan was
settled on from FY2013 Priority area
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.
http://kyushu.env.go.jp/naha/wildlife/data/gairai/boujyo/130425b.html 29Education & Awareness
Pamphlet for the mongoose eradication measure
30
http://kyushu.env.go.jp/naha/wildlife/data/gairai/boujyo/131017a.pdfThank you for your attention
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