3

Values and Challenges of the Ogasawara Islands
in Comparison with Other Island World Heritages
Masahito YOSHIDAWorld Heritage Studies, Graduate School of Comprehensive Human Sciences, University of Tsukuba
1-1-1 Tennodai, Tsukuba, Ibaraki 305-8571, Japan

Abstract
The Ogasawara Islands were inscribed in the World Heritage List in 2011, recognized for their
Outstanding Universal Value of the on-going process of biological evolution in remote oceanic islands. In a
comparative study with other island World Heritage sites, the Ogasawara Islands showed characteristics ofboth island World Heritage sites with human settlements and island World Heritage sites without humansettlements. To address the invasive alien species issue that threatens the Outstanding Universal Values of the
Ogasawara Islands, strict biosafety measures are essential to safeguard the endemic species. To address theissue of infrastructure development, vigorous prior environmental impact assessments are required.
Key words :	environmental impact assessment, invasive alien species, island World Heritage,
Outstanding Universal Value

1. Introduction
The Ogasawara Islands are a chain of oceanic islands
located 1,000 km south of the main islands of theJapanese archipelago. The Ogasawara Islands consist of
more than 30 islands, extending 400 km from north tosouth. These islands are divided into four island groups,
namely, the Muko-Jima Islands, Chichi-Jima Islands,
Haha-Jima Islands, Kazan Islands and Nishino-Shima
Island, an active volcano (Yoshida, 2018).
Geologically, the Ogasawara islands are unique inthe world for allowing us to witness how an oceanicisland arc has been created from the beginning of theoceanic tectonic plate subduction around 48 million years
ago. Biologically and ecologically, the islands provide
evidence of ongoing biological evolution in remoteoceanic islands that have formed unique endemic species,
especially those of land snails, insects and vascular plants(Government of Japan, 2010).
Recognizing the Outstanding Universal Value of ongoing processes of biological evolution, UNESCO’s
World Heritage Committee decided to inscribe theOgasawara Islands in the World Heritage List in June
2011. The world heritage area covers 6,358 ha ofterrestrial area and 1,581 ha of surrounding marine area
(Government of Japan, 2010).
This paper analyzes the conservation measures takenin the Ogasawara Islands after its World Heritage
inscription in comparison with other island World
Heritage sites and proposes future challenges.

Global Environmental Research
23/2019: 003-008
printed in Japan

2.	Outstanding Universal Values of the
Ogasawara Islands
The Ogasawara Islands exhibit significant scientificvalue not only with regard to their biological andecological aspects but also the geological aspects of theseislands. The Ogasawara Islands are part of the IzuOgasawara Arc that was created by subduction of the
Pacific plate beneath the Philippines Sea plate starting
around 48 million years ago. The Izu-Ogasawara Arc is
one of the most studied island groups in terms ofgeophysics, geology and petrology because of itsscientific importance as a typical example of an oceanicisland arc. A continuous history of the island arc’s
growth, from its birth to the present date, is recorded in
the form of changes in magma chemical composition andvolcanic activity (Government of Japan, 2010).
The geological value of the Ogasawara Islands,
however, was not recognized as an Outstanding Universal
Value at the World Heritage Committee meeting held in
2011, though the ongoing ecological and biologicalevolution process of endemic species was recognized(World Heritage Committee, 2011).
Since the Ogasawara Islands have never beenconnected to any continental landmass, plants andanimals of the Ogasawara Islands are descendants ofpioneer species that arrived by flight, were blown in by
the wind or floated over on sea currents. For example, theBonin flying fox (Pteropus pselaphon) is the only nonintroduced terrestrial mammal that inhabits the
Ogasawara Islands. The Ogasawara snake-eyed skink©2019 AIRES

4

M. YOSHIDA

Fig. 1 
The Ogasawara Islands were inscribed on the World
Heritage List at the 35th World Heritage Committee meeting
held in Paris.

(Cryptpblepharus nigropunctatus) and Gunther’s tropical
gecko (Perochirus ateles) are the only two reptile species
that inhabit the Ogasawara Islands. No amphibious
species have successfully migrated to the Ogasawara
Islands except for the introduced bullfrog (Lithobates
catesbeiana), which was eradicated on Ototo-Jima in
2008.
Among 104 land snail species in these islands, 98
species (94%) are endemic to the Ogasawara Islands.
Recent DNA studies of land snails tell a distinctive storyof adaptive radiation of land snails in the Ogasawara
Islands. Adaptive radiation of land snails was considered
to show evidence of significant biological value thatmeets criterion (ix) on-going ecological and biologicalprocesses regarding the Outstanding Universal Value of
the Ogasawara Islands as a Natural World Heritage.
In 2011, the Ogasawara Islands were inscribed in theWorld Heritage List at the 35th World Heritage Committee
meeting held by UNESCO in Paris (Fig. 1).

3.	Comparison with Other Island World
Heritage Sites
Among 1,121 World Heritage sites, 213 are natural
World Heritage sites and 39 are mixed cultural and natural
World Heritage sites as of 2019. Among the 252 naturaland mixed World Heritages, around 40 sites are locatedon islands and can be classified as island World Heritage
sites (Table 1). However, large terrestrial heritage sites
located in island countries such as Te Wahipounamu andTongariro National Park in New Zealand, TasmanianWilderness World Heritage in Australia and Lorentz
National Park in Indonesia are excluded because thesesites represent terrestrial ecosystems of larger islands
rather than island ecosystems of smaller ones.
Among 40 island World Heritage sites, 19 arelocated in the Pacific Ocean and 11 in the Atlantic Ocean(including the Baltic and Caribbean seas). Three are in

the Indian Ocean, two in the Mediterranean, one in the
Arctic Ocean and four in the Antarctic Ocean. At least, 13
island World Heritage sites are volcanic islands and eight
are atolls or islands fringed by coral reef.
Looking at the criteria for nomination, 24 island
World Heritage sites meet criterion (vii) natural beauty,
23 meet criterion (ix) ecosystem, 22 meet criterion (x)biodiversity and 13 satisfy criterion (viii) Earth’s history.
Taking examples from Japan, Yaku-Shima meets criterion(vii) natural beauty of the Yakusugi cedar forest and (ix)horizontal zoning of vegetation, while the Ogasawara
Islands meet criterion (ix) on-going biological evolutionof endemic species.
Four island World Heritage sites, St.Kilda of UK,
Papahanaumokuakea of the USA, Rock Island Southern
Lagoon of Palau and Blue and John Crow Mountains ofJamaica, are mixed World Heritage sites that meet bothnatural and cultural criteria.
The largest island World Heritage site is French
Austral Lands and Seas located in the Antarctic Ocean
that covers 67,296,900 ha (1.8 times larger than the landarea of Japan), inscribed in 2019. The second largest is
Phoenix Island of Kiribati, covering 40,825,000 ha. The
third largest is Papahanaumokuakea of Hawaii, covering
36,207,499 ha, and the fourth largest is the Galapagos
Islands of Ecuador, covering 14,066,514 ha. Thoseislands comprise both terrestrial and marine areas thatsurround the islands and contribute to achievement of the
Aichi Biodiversity Targets, in which State Parties to theConvention on Biological Diversity are required todesignate at least 17% of their land and 10% of theirmarine areas as protected areas by 2020.
The unique ecosystems of the Ogasawara Islands
have been threatened by the introduction of invasive alien
species. All listed island World Heritage sites are facing
the same problem. Island World Heritages inscribed in
the World Heritage List in the 1970s to 1980s, such as theGalapagos Islands of Ecuador, Aldabra Atol of
Seychelles, Lord Howe Island of Australia, St. Kilda andHenderson Island of the UK, Grajonay National Park of
Spain and Hawaii Volcanoes National Park of the USA
have suffered from invasive alien species. Intentionallyintroduced animals such as goats (Galapagos Islands),
sheep (St. Kilda), rats and cats (Aldabra Atol, Garajonay
National Park and Henderson Island), boars (Lord Howe
Island) and pigs (Hawaii Volcanoes) are traditional
introduced species that threaten endemic species,
especially avifauna.
Island World Heritage sites inscribed after the 1990s,
such as Macquire Island, Heard and McDonald Islands ofAustralia, Surtsey of Iceland, French Austral Lands andSeas of France, Archipiélago de Revillagigedo of Mexico,
the Sub-Antarctic Islands of New Zealand andPapahanaumokuakea of the USA are islands that once
experienced human settlement and introduction of alien
species, but intensive invasive species control measures

Values and Challenges of the Ogasawara Islands

5

Table 1 Island World Heritages within Natural and Mixed Heritages.
Year of
Inscription
1978
1982
1982
1986
1986
1987
1987
1988
1991
1991
1992
1993
1993
1995
1996
1997
1997
1997

Name of Poperty

State Party

Galapagos Islands
Aldabra Atol
Lord Howe Islnd
St.Kilda
Garajonay NP
Gros Morne NP
Hawaii Volcanoes NP
Henderson Island
Komodo NP
Ujung Kulon NP
Frazer IslandYaku-Shima
Tubbataha Reefs NP
Gough and Inaccessible
IslandBelize Barrier Reef
Cocos Island NP
Macquire Island
Heard and McDonald
Islands

Equator
Seychelles
Australia
UK
Spain
CanadaUSA
UK
Indonesia
Indonesia
Australia
Japan
Phillipines

2004
2006
2007
2007
2008
2008
2010
2010
2010
2011
2012
2013
2015
2016
2016
2019
Total

1
1
1
1

iii, v

1
1
1
1
1
1

1
1

Australia

1

1
1
1
1

1
1
1
1
1
1

1
1
1

1

Place of the Island(s)Topography
Area ofIndianCoral Property (ha)Pacific Atlantic MediteranianArctic Antarctic Volcanoe
Sea
Reef
1
1
14,066,514
1
1
35,0001
114,3001
24,201
13,984
1180,500
1
1
92,934
1
1
3,700
1
1
219,3221
1
123,100
1
184,000
1
10,7471
196,800

1
1
1

1
1

1

1

1

1

1
1

1

1
1
1

1
1

1

1

1

1

1

1

iii, v

140,700
1,915,600
857,500

1
1

1

1

1

1

1

1

1
1
1

1

1

1
1
1

1

1

1

1

1
1

1

1

1

1

1

24 13 23 22

were undertaken before inscription on the World Heritage
List.
Macquire Island, located 1,500 km south of Tasmania,
suffered from various invasive species such as rabbits,

9,522

1
1

18,99033,700410,460

1

105,83811

1

1

36,207,499
40,825,000
7,939

1iii, vi

1,216

1
1

1

1

1

1

1

100,200
19,237

1

26,252

1

146

1

1

636,685

1
19

5,753
336,900

1
1

37,00076,4581

196,300199,790557,280
658,903

1

1
1

1

1

1

1

iii, vi

1
1

1
1

1

1

397,900

1

SolomonIslands
NewZealand

Sub-Antarctic Islands
Puerto-Princesa
Phillipines
Subterranean River NP
High Coast/Kvarken
Finland/
Archipelago
SwedenIsole Eolie
Italy
Brazilian Atlantic
BrazilIslands
Wrangel Island
RussiaMalpelo Fauna andColombia
Flora Sancturay
Jeju Volcanic Island andKorea
Lava Tubes
Teide National Park
Spain
Surtsey
Iceland
Socotra Archipelago
Yemen
Pitons cirques andremparts of Reunion
FranceIslands
Papahanaumokuakea
USA
Phoenix Islands
Kiribati
Ogasawara Islands
Japan
Rock Islands Southern
Palau
LagoonMt.Etna
Italy
Blue and John Crow
JamaicaMountains
Mistaken Point
CanadaArchipiélago de
MexicoRevillagigedo
French Austral Lands
Franceand Seas

2001

1
1
1
1
1
1

BelizeCosta Rica
Australia

1998

2000

x

1

East Rennell

2000

i〜vi vii viii ix

UK

1998

1999

Criteria for Inscription

11

2

3

1

4

67,296,900
13

8

166,034,770

cats, rats and mice. However, an intensive invasive species
control program eradicated feral cats before its inscription
and rabbits, rats and mice were eradicated by 2016. In
New Zealand’s Subantarctic Islands, eradication programs

6

M. YOSHIDA

for pigs, cats and mice on Auckland Island and an
eradication program for mice on Antipodes Island werecarried out under their management plan. In Gough andInaccessible Islands of the UK located in the southern
Atlantic and Archipiélago de Revillagigedo of Mexico in
the eastern Pacific, eradication of introduced species has
been addressed by the authorities in charge of their
management.
Created by eruptions in 1963-1967, Surtsey Island of
Iceland is the best place in the world to observe theprimary succession of plants and colonization of animals
after a volcanic eruption. To prevent the introduction of
non-native species by human beings, the Ministry of theEnvironment of Iceland strictly prohibits access to theisland. In the case of Heard Island and McDonald Islandsof Australia, only limited numbers of visitors can receive
permission to enter these islands from the Australian
Antarctic Division of the Department of the Environment
and Energy, Australian Government.
The Ogasawara Islands have characteristics of bothisland World Heritage sites inscribed in the World
Heritage List in the 1970s to 1980s and island World
Heritage sites inscribed after the 1990s. In terms ofhuman settlement, Chichi-Jima and Haha-Jima islands,
inhabited by 2,500 people, are in a condition similar toisland World Heritage sites with human settlements thatwere inscribed in the 1970s to 1980s. On the other hand,the small isolated islands, home to endemic plants andanimals, are under similar circumstances to island World
Heritage sites that had once experienced humansettlement but had their invasive species controlled after
their inscription. To preserve the remaining habitat ofendemic species, it will be necessary to control access tothese remote islands and prevent unintentional invasionof invasive alien species.

4. Future Challenges in the Ogasawara Islands
Conservation of the Ogasawara Islands faces many
challenges. The World Heritage Committee, however,focused on two challenges, namely prevention of alien
species’ invasions and control of human impact on naturewhen the Ogasawara Islands were inscribed on the World
Heritage List in 2011. The World Heritage Committee
adopted a decision to request the State Party (Governmentof Japan) to continue its efforts to address invasive alien
species and to ensure all significant infrastructuredevelopment, including tourism and access to the islands,
was subject to rigorous prior environmental impact
assessment (World Heritage Committee, 2011).
As to the first request on invasive alien species, theMinistry of the Environment, together with the Forestry
Agency, Tokyo Metropolitan Government and Ogasawara
Village, has been involved in the eradication of
established alien species populations and prevention of
introduction of new invasive species since the Ogasawara

Fig. 2 The red-headed wood pigeon population has increased since
the feral cat program started.

Islands were listed as a candidate for natural World
Heritage in 2003.
Eradication of goats, pigs, rats and bullfrogs was
successfully completed in the remote islands before
inscription, but eradication of goats, cats and rats has not
yet been completed on the inhabited islands of ChichiJima and Haha-Jima. The eradication program for cats on
Chichi-Jima Island has been highly evaluated by the
IUCN as an eradication program that considered both theconservation of endemic species, red-headed wood
pigeon (Columba janthina nitens: a critically endangered
species in the Ministry of the Environment’s Red List)(Fig. 2) and humane treatment of feral cats. To reach aconsensus, the Institute of Boninology, together with
IUCN’s Conservation Breeding Specialist Group of theSpecies Surviving Commission (CBSG/SSC), held aninternational workshop on conservation planning for thewood pigeon on Chichi-Jima Island in 2008 (Horikoshi etal., 2010). The feral cat eradication program has been
conducted in a careful manner on Chichi-Jima Island
since 2008. Captive feral cats are not killed but
transferred to a clinic of the Tokyo Veterinary Medical
Association where they are trained as companion animals
to find another host. The wood pigeon population has
increased since 2011, bearing testimony to the success of
this program (Sasaki, 2014).
The green anole (Anolis Carolinensis) (Fig. 3) is analien lizard that was introduced from North America, via
Guam, during the era of US occupation after World War
II. Anoles are voracious predators of endemic insect
fauna in the Ogasawara Islands and were listed as a
Designated Invasive Alien Species under the Invasive
Alien Species Act in 2005. The distribution of green
anole was limited to human-inhabited islands, but a new
population was found on Ani-Jima Island, home to rareendemic insects of the Ogasawara Islands, in 2013. The
Ministry of the Environment launched an eradication
program for the green anole on Ani-Jima Island. They set
up a long fence to prevent further invasion of green anoleValues and Challenges of the Ogasawara Islands

7Fig. 3 The green anole extended its distribution from Chichi-Jima
Island to Ani-Jima Island in 2013.

Fig. 5 Tourists are encouraged to clean the soles of their shoes
with brushes and vinegar spray.

Fig. 4 Long fences built to prevent the green anole from extending
its distribution on Ani-Jima Island.

Fig. 6 Electric fences built to prevent the New Guinea flatworm
from extending its distribution.

(Fig. 4), but the anole population has not yet been
eradicated.
The New Guinea flatworm (Platydemus manokwari)
is a carnivorous flatworm introduced as a predator of East
African land snail (Achatina fulica), a wide-ranging alien
species in the Pacific islands. While the East African landsnail population has decreased, the New Guinea flatworm
has become a major predator of endemic land snails in
the Ogasawara Islands. The flatworm was listed as a
Designated Invasive Alien Species under the Invasive
Alien Species Act in 2005. Since the distribution of the
New Guinea flatworm is restricted to Chichi-Jima Island,
the Ministry of the Environment is focusing its efforts on
preventing expansion of the flatworm’s distribution toother islands. Tourists are encouraged to clean the solesof their shoes with brushes and spray them with vinegar
before landing on other islands or entering important
habitats of endemic species (Fig. 5). The Ministry of theEnvironment set up an electric fence to prevent expansionof flatworms into endemic land snail habitat on ChichiJima Island in 2014 (Fig. 6). It was reported, however,that the flatworm had expanded its distribution despite
the electric fence in 2018. Further efforts will be required

to prevent their further invasion by cleaning equipment,
construction vehicles and scaffolding pipes before
transferring them from Chichi-Jima Island to otherislands.
A potential pathway for the flatworm to invade otherislands is through soil associated with imported mango
saplings pots introduced from the Okinawa Islands. Soilin the sapling pots may include carnivorous flatworms
and another invertebrates that are harmful to bothendemic species and farm products. In fact, alien ants,
diplopods and carnivorous flatworms were found in thesoil of mango sapling pots introduced from the Okinawa
Islands in 2016 (Working Group on Prevention ofIntroduction of New Alien Species, 2016). The Ministryof the Environment introduced a measure to clean up thesoil using hot water at the port of Haha-Jima Island in
2019.
The big-headed ant (Pheidole megacephala) (Fig. 7)
is one of the alien species that pose a significant threat,along with the Argentine ant (Linepithema humile), crazyant (Anoplopsis gracilipes), red imported fire ant(Solenopsis invivta), and little fire ant (Wasmannia
auropunctata). These species are listed on the 100 of the8

M. YOSHIDA
Government, was to clear-cut the sclerophyll scrub on
Ani-Jima Island (Fig. 8). Scientific studies, however,revealed that the sclerophyll scrub is an important habitatfor endemic land snails. The Tokyo Metropolitan
Government finally gave up its plan to construct a
commercial airport in 2001 (Nature Conservation Societyof Japan, 2002; Shimizu, 2003). Ogasawara Village,
however, has not given up its plan to construct a small
airport for the villagers, and it may be detrimental to theenvironment in the light of fact that the World Heritage
Committee has requested the Government of Japan toundertake a rigorous environmental impact assessment
prior to the construction of an airport.

Fig. 7 B
 ig-headed ants attracted by bait at Futami Port, Chichi-Jima
Island.

Fig. 8 Ani-Jima Island, where the Tokyo Metropolitan Government
was planning an airport in the 1990s.

World’s Worst Invasive Alien Species list compiled by
IUCN (Lowe et al., 2000). The big-headed ant hasestablished a population at Futami Port on Chichi-Jima
Island and was discovered in an important habitat forland snails on Haha-Jima Island in 2014. The Ministry of
the Environment successfully eradicated this incidental
population in 2016. The Argentine ant established apopulation in the western part of Japan, but was
discovered and successfully eradicated in Tokyo in 2017.
The crazy ant was first discovered in Tokyo Bay in acontainer of a container ship from southern China in2017. The red imported ant had already established apopulation on Iwo-Jima Island in the Ogasawara Islands
before, but it was discovered in Tokyo Bay in 2018. Strict
biosafety measures will be essential to prevent
introduction and expansion of invasive alien species andsafeguard the endemic species that represent the
Outstanding Universal Values of the Ogasawara Islands.
As to the second request of the World Heritage
Committee, during their field mission to the Ogasawara
Islands in 2010, the IUCN expressed their concern thatthe airport construction plan could increase the number oftourists to the Ogasawara Islands. The original airport
construction plan, developed by the Tokyo Metropolitan

References
Government of Japan (2010) Nomination of the Ogasawara Islands
for inscription on the World Heritage List. Retrieved from http://
www.ogasawara-info.jp/pdf/isan/recommendation_en.pdf
Horikoshi, K., Itoh, K., Hayama, S., Maruyama, A., Suzuki, H.,
Traylor-Holzer, K., Ballou, J. and Miller, P. (eds.) (2010) Readheaded wood pigeon population and habitat viability assessment
workshop final report, Conservation Breeding Specialist Group,
IUCN/SSC, Apple Valley, MN.
Lowe, S., Browne, M., Boudjelas, S. and De Pooter, M. (2000) 100of the World’s Worst Invasive Alien Species: A selection of the
global invasive species database, Invasive Species Specialist
Group, SSC, IUCN.
Nature Conservation Society of Japan (2002) Fifty years record ofnature conservation NGO, Heibonsha, Tokyo. (in Japanese)
Sasaki, T. (2014) Cat control in Ogasawara Islands : current stage.
Veterinary Medical Association Journal, 564, 18–19. (in Japanese)
Shimizu, Y. (2003) The nature of Ogasawara and its conservation.
Chikyu Kankyo, 7(1), 3–13. (in Japanese)
World Heritage Committee (2011) Decision 35 COM8B.11 Natural
Properties : Ogasawara Islands (Japan). Retrieved from http://
whc.unesco.org/en/decisions/4282
Working Group on Prevention of Introduction of New Alien
Species (2016) Strategy to Prevent Introduction and Expansionof Alien Species in Ogasawara Islands Natural World Heritage
area, Ministry of the Environment, Japan. (in Japanese)
Yoshida, M. (2018) Ogasawara Islands World Heritage Area: An
outstanding ecological heritage. In: Chakraborty et al. (eds.)
Natural Heritage of Japan. Geoheritage, Geoparks andGeotourism, 61–72, Springer International.

Masahito YOSHIDA
Masahito Yoshida is a Professor of World
Heritage Studies at the Graduate School of the
University of Tsukuba. He is a member of IUCN’s
World Commission on Protected Areas (WCPA)
and Vice-Chair of WCPA Japan. He is also serves
as Executive Director of the Nature Conservation
Society of Japan. Papers he has authored include“World Natural Heritage and the Conservation of Biological Diversity,”“Sekai Isan wo Toinaosu (Reconsidering the World Heritage Convention),”and “Shizen Hogo—Sono Seitaigaku to Shakaigaku (Nature Conservation –its Ecology and Sociology).” Prof. Yoshida also co-translated the World
Resources Institute’s Conserving the World’s Biological Diversity.
(Received 16 October 2019, Accepted 13 December 2019)