Journal of Threatened
Taxa | www.threatenedtaxa.org | 26 May 2025 | 17(5): 27021–27025
ISSN 0974-7907 (Online) | ISSN 0974-7893 (Print)
https://doi.org/10.11609/jott.9514.17.5.27021-27025
#9514 | Received 26 November 2024 | Final received 25 February 2025 |
Finally accepted 07 May 2025
First post-tsunami report of
Coconut Crab Birgus latro
(Linnaeus, 1767) (Malacostraca: Decapoda: Coenobitidae) in Car Nicobar Island, Nicobar Archipelago
Mayur Fulmali
1, Dhanesh Ponnu 2 &
Nehru Prabakaran 3
1,2,3 Wildlife Institute of India,
Wildlife Road, Chandrabani, Dehradun, Uttarakhand
248001, India.
1 drfulmalimayur1998@gmail.com, 2
radhadhanesh.p@gmail.com, 3 nehrumcc@gmail.com (corresponding
author)
Editor: M. Nithyanandan,
Kuwait Institute for Scientific Research (KISR), Salmiya, Kuwait. Date of publication: 26 May 2025
(online & print)
Citation: Fulmali, M., D. Ponnu & N. Prabakaran
(2025).
First post-tsunami report of Coconut Crab Birgus
latro (Linnaeus, 1767) (Malacostraca: Decapoda: Coenobitidae) in Car
Nicobar Island, Nicobar Archipelago. Journal of Threatened Taxa 17(5): 27021–27025. https://doi.org/10.11609/jott.9514.17.5.27021-27025
Copyright: © Fulmali et al. 2025. Creative Commons Attribution 4.0
International License. JoTT allows unrestricted use,
reproduction, and distribution of this article in any medium by providing
adequate credit to the author(s) and the source of publication.
Funding: This study was funded by the Ministry of Environment, Forest and Climate Change, Government of India, under the Integrated Development of Wildlife Habitats (IDWH) scheme.
Competing interests: The authors declare no competing interests.
Acknowledgements: We thank the Andaman & Nicobar Forest Department for their support. We are grateful to the Dean and Director of Wildlife Institute of India for their support and encouragement during the study. We also thank Mr. George and Nicobari Village head for their help and support during the fieldwork.
Abstract: Remote islands in the
Indo-Pacific are crucial habitats for Birgus
latro, the world’s largest terrestrial arthropod.
The 2004 tsunami severely impacted its populations in the Nicobar Archipelago,
with no sightings on Car Nicobar Island. This study documents the first
post-tsunami opportunistic record, highlighting the species’ resilience and
extending its northernmost distribution in the Nicobar group of islands.
Keywords: Andaman & Nicobar Islands, Anomura, coastal ecosystem, crustacean, distribution, habitat
loss, island biodiversity, recovery, tropical ecology.
The Coconut Crab Birgus latro
(Linnaeus, 1767) is the largest land arthropod and one of the decapod
crustaceans, most adapted to terrestrial life (Lavery
et al. 1996). With a leg span reaching up to 1 m and a weight of up to 5 kg, it
can live as long as 60 years (Sato & Yoseda 2013;
Cumberlidge et al. 2022). These crabs possess a
highly developed olfactory sense (Stensmyr et al.
2005) and are opportunistic scavengers, feeding on a wide variety of foods,
including fallen fruits & nuts of Pandanas, Barringtonia, Areca Nut, Coconut, and animal remains (Reyne
1939; Daniel & Premkumar 1968). The IUCN Red List
status of B. latro was updated from ‘Data Deficient’
to ‘Vulnerable’, based on its distribution, threats, and population trends (Cumberlidge et al. 2022). In India, it is protected under
the Schedule I–A of the Wildlife Protection Act, 1972.
Birgus latro is distributed widely across the
Indo-Pacific region, particularly inhabiting the remote rocky shores of small
oceanic islands and atolls. Within the Andaman & Nicobar Islands, it is primarily
found throughout the Nicobar Archipelago and on a few islands in the Andaman
Archipelago (Hume 1874; Alcock 1905; Daniel & Premkumar 1968; Sivaperuman et
al. 2023). In the Nicobar group of islands, it has been documented from Great
Nicobar, Little Nicobar, Kamorta, Nancowry,
Katchal, Teressa, Chowra,
Trinket, Bambokka, Tillangchong,
and several smaller islands (Alcock 1905; Daniel
& Premkumar 1968; Sankaran et al. 2005; Sivakumar
2010; Patankar & D’souza
2012; Zaibin et al. 2012; Sivaperuman
et al. 2023) (Image 1). In Car Nicobar, the northernmost island in the Nicobar
Archipelago, its presence was first documented by Hume (1874), and no further report of this
species is available (Patankar & D’souza 2012; Sivaperuman et al.
2023).
Coconut Crabs in coastal habitats are vulnerable to
habitat loss from anthropogenic activities and geological events, such as
tsunamis (Sivakumar 2010; Caro et al. 2021). The 2004 Indian Ocean tsunami
extensively devastated coastal habitats across the Andaman & Nicobar Archipelago
(Sankaran et al. 2005). A rapid post-tsunami wildlife assessment provided an
overview of the surviving coastal flora and fauna, with preliminary
observations on the distribution of B. latro
(Sankaran et al. 2005; Sivakumar 2010). Post-tsunami records from Kamorta, Menchal, and Great
Nicobar confirmed the continued presence of B. latro
in the Nicobar Islands (Patankar 2007). Although
Hume’s (1874) record is the only documented pre-tsunami report of B. latro from Car Nicobar Island, no post-tsunami records
have been documented. Efforts to locate Coconut Crabs during the post-tsunami
surveys on Car Nicobar were unsuccessful (Patankar
& D’souza 2012), which may have led to the
exclusion of this island in the subsequent study by Sivaperuman
et al. (2023).
This paper presents the first post-tsunami incidental
sighting of B. latro on Car Nicobar Island,
thereby providing an updated distributional record. On 13 April 2024, a single B.
latro specimen was observed (Geographical
coordinates: 9.1640 0N, 92.7990 0E) and photographed from
Car Nicobar Island (Images 1 & 2). The absence of pleopods identified the
specimen as male (carapace length: 121 mm; cephalothoracic
width: 52 mm), weighing approximately 1,220 g. Locally known as ‘Nyiońv’ (/njuː/) in ‘Pu’ (Car Nicobar),
a dialect of the Nicobarese language. The Coconut
Crab was found in a subsurface limestone karst, a small cave located 3.36 km
inland from the east coast of Car Nicobar (Image 1). The presence of coconut
fruit and anthropogenic litter inside (the cave is a recreation spot, resulting
in the spillover of food waste) the cave may have attracted the Coconut Crab
(Image 2). Discarded food packaging and plastic waste pose significant hazards,
as crabs can become entangled or ingest harmful materials. As adult B. latro individuals prefer residing inland or the
interior forest (Sato & Yoseda 2013), it becomes
crucial to include interior forests and inland caves in survey efforts.
Surveying these inland populations remains challenging due to the cryptic
nature and nocturnal behaviour of the species.
Moreover, B. latro appears to persist in other
areas of Nicobar Islands where earlier surveys, such as Patankar
& D’souza (2012) and Sivaperuman
et al. (2023), were unsuccessful in detecting its presence. Pre- and
post-tsunami records of B. latro from the
Andaman & Nicobar Islands have indicated the reduction in its distribution
range (Table 1). Incidental sightings like this can guide surveys in regions
such as Trinket, Kondul, and Chowra,
previously thought to be locally extirpated (Sivaperuman
et al. 2023; Patankar & D’souza
2012). These regions require additional systematic monitoring of Coconut Crabs
to better understand their distribution. Moreover, events like the tsunami may
significantly impact its home range, population recovery, genetic diversity,
and migration pattern.
For species such as Coconut Crabs, which are rare,
elusive, or in challenging environments, incidental sightings provide valuable
insights into the species’ presence, behaviour, or
habitat preferences that might otherwise remain undocumented. This record
highlights the importance of surveying interior forests, particularly areas
with geological structures like caves, for detecting coconut crabs. This study
extends the northernmost recorded distribution of B. latro
within the Nicobar Archipelago, highlighting the importance of Car Nicobar as a
key site for future survey efforts.
Table 1. Pre- and post-tsunami distributional records of Coconut Crabs Birgus latro from
the Andaman & Nicobar Islands. (+)—present as per local ecological
knowledge of Nicobari Tribe | ( )—not
been surveyed yet | (-)—surveyed but not found | *—Distribution referring to
Nicobar Islands without specifying a particular island.
|
Island |
Island subgroup |
Island |
Observations |
Reference |
|
|
Pre-tsunami records |
Post-tsunami records |
||||
|
Andaman group |
South Andaman |
South Sentinel |
1905, 1976 |
Alcock 1905; Altevogt & Davis 1976 |
( ) |
|
Little Andaman |
1905, 2015–2018 |
Alcock 1905 |
Sivaperuman et al. 2023 |
||
|
Nicobar group |
Car Nicobar |
Car Nicobar |
1874 |
Hume 1874 |
(This study) (-) Patankar & D’souza 2012 |
|
Nancowry |
Teressa |
2015–2018 |
(+) |
Sivaperuman et al. 2023 |
|
|
Chowra |
2011 |
(+) |
Zaibin et al. 2012 |
||
|
Bambokka |
2015–2018 |
(+) |
Sivaperuman et al. 2023 |
||
|
Kamorta |
2015–2018 |
(+) |
Patankar 2007; Sivaperuman et al.
2023 |
||
|
Trinket |
|
(+) |
( ) |
||
|
Katchal |
2006, 2015–2018 |
(+) |
Sivakumar 2010; Sivaperuman
et al. 2023 |
||
|
Nancowry |
2015–2018 |
(+) |
Sivaperuman et al. 2023 |
||
|
Tillangchong |
2005, 2006, 2015–2018 |
(+) |
Sankaran et al. 2005; Sivakumar 2010 |
||
|
Great Nicobar |
Little Nicobar |
2015–2018 |
(+) |
Sivaperuman et al. 2023 |
|
|
Menchal |
2005, 2006, 2008, 2015–2018 |
Altevogt & Davis 1975 |
Sankaran et al. 2005; Sivakumar 2010; Sivaperuman et al. 2023; Patankar
2007; Patankar & D’souza
2012 |
||
|
Meroe |
1975, 2015–2018 |
Altevogt & Davis 1975 |
Sivaperuman et al. 2023 |
||
|
Treis |
2005 |
(+) |
Sankaran et al. 2005 |
||
|
Trax |
2005 |
(+) |
Sankaran et al. 2005 |
||
|
Kondul |
2015–2018 |
( ) |
(-) Sivaperuman et al.
2023 |
||
|
Great Nicobar |
1966, 2007 |
Daniel & Premkumar
1968 |
Patankar 2007 |
||
|
|
1932 |
*Man 1932 |
|
||
For
images - - click here for full PDF
References
Alcock, A. (1905). Anomura. Fasc. I.
Pagurides. Catalogue of the Indian Decapod Crustacea
in the collection of the Indian Museum, Part II. Anomura.
Fasciculus I. Pagurides. Trustees of the Indian
Museum, Calcutta, 197 pp.
Altevogt, R. & T.A. Davis (1975). Birgus latro, India’s Monstrous Crab: a study and an appeal. Bulletin
of the Department of Marine Sciences 7: 11–24.
Caro, T., H. Hamad, R.S. Rashid,
U. Kloiber, V.M. Morgan, O. Nokelainen,
B. Caro, I. Pretelli, N. Cumberlidge
& M.B. Mulder (2021). A case study
of the Coconut Crab Birgus latro on Zanzibar highlights global threats and
conservation solutions. Oryx 55(4): 556–563. https://doi.org/10.1017/S0030605319000863
Cumberlidge, N., T. Caro, V.M. Watson-Zink, T. Naruse, P.K.L. Ng, P.K.M. Orchard, D.L. Rahayu,
D. Wowor, D.C.J. Yeo & T. White (2022). Troubled giants: the updated conservation status of
the Coconut Crab Birgus latro.
Raffles Bulletin of Zoology 70: 1–21. https://doi.org/10.26107/RBZ-2022-0001
Daniel, A. & V.K. Premkumar (1968). The Coconut Crab, Birgus
latro (Crustacea: Paguridae)
in the Great Nicobar Island. Journal of the Bombay Natural History Society
64: 514–580.
Hume, A.O. (1874). Contributions to the ornithology of India: the
islands of the Bay of Bengal. Stray Feathers 2: 29–324.
Lavery, S., C. Moritz & D.R. Fielder (1996). Indo-Pacific population structure and evolutionary
history of the Coconut Crab Birgus latro. Molecular Ecology 5(4): 557–570. https://doi.org/10.1046/j.1365-294X.1996.00125.x
Man, E.H. (1932). The Nicobar Islands and Their People. Printed
and published: For the Royal Anthropological Institute of Great Britain and
Ireland by Billings and Sons Ltd., Guildford, England, 109 pp.
https://dokumen.pub/the-nicobar-islands-and-their-people.html (Accessed: 3
September 2024).
Patankar, V. (2007). First post-tsunami sighting of the Coconut Crab in
the Nicobar Islands. Oryx 41(3): 287–288. https://doi.org/10.1017/S0030605307004133
Patankar, V. & E. D’souza
(2012). Conservation needs of the Coconut
Crab Birgus latro
on the Nicobar Islands, India. Oryx 46(2): 175–178. https://doi.org/10.1017/S0030605311000408
Reyne, A. (1939). On the food habits of the Coconut Crab Birgus latro L.,
with notes on its distribution. Archives Néerlandaises
de Zoologie 3(2): 283–320. https://doi.org/10.1163/036551639X00345
Sankaran, R., H. Andrews & A.
Vaughan (2005). Ground beneath the waves:
post-tsunami impact assessment of wildlife and their habitats in India, pp.
1–103. In: Kaul, R. & V. Menon (eds.). The Islands. Wildlife Trust
of India, New Delhi, 427 pp.
Sato, T. & K. Yoseda (2013).
Reproductive migration of the Coconut Crab Birgus
latro. Plankton and Benthos Research 8(1):
49–54. https://doi.org/10.3800/pbr.8.49
Sivakumar, K. (2010). Impact of tsunami on certain rare and threatened
species of Nicobar group of islands with special reference to the Nicobar
megapode Megapodius nicobariensis,
pp. 435–441. In: Raghunathan, C.R.C. & C. Sivaperuman
(eds.). Recent Trends in Biodiversity of Andaman and Nicobar Islands.
Zoological Survey of India, Kolkata, xii+542 pp.
Sivaperuman, C., C. Smitanjali & G.
Gokulakrishnan (2023). Status estimation of Coconut Crab Birgus
latro (Linnaeus, 1767) from Andaman and Nicobar
Islands, India. Proceedings of the Zoological Society 76(3):
275–287. https://doi.org/10.1007/s12595-023-00487-0
Stensmyr, M.C., S. Erland, E.
Hallberg, R. Wallén, P. Greenaway & B.S. Hansson
(2005). Insect-like olfactory adaptations
in the terrestrial Giant Robber Crab. Current Biology 15(2): 116–121. https://doi.org/10.1016/j.cub.2004.12.069
Zaibin, A.P., N. Prabakaran, P.
Pramod, L. Vijayan, R. Sankaran & P. Balasubramanian (2012). Monitoring post-tsunami coastal ecosystem recovery in
the Nicobar Islands and developing site-specific restoration measures (PR No.
104). Accessed on 22 November 2024. Technical Report. Salim Ali Centre for
Ornithology & Natural History. https://www.sacon.in/wp-content/uploads/2015/06/2012-PR104-Monitoring-Post-Tsunami-Coastal-Ecosystem-Recovery-in-the-Nicobar-Islands-to-Developing-Site-Specific-Restoration-Measures.pdf