The Galápagos Giant TortoiseA Conservation Conundrum

By: Ellie de Cent, Daniel Callan and George Hancock

Group: 72

Chelonoidis nigara:

Endemic to the Galápagos islands – an archipelago off the west coast of Ecuador

10 extant subspecies/ races, divided into two categories:

The Largest living tortoise

1. Domed-shells

2. Saddleback shells

C. n. chathamensisC. n. abingdonii

Reference: Burnie, D. (2001) Animal. Dorling Kindersley, London

Evolution and Ecology:

Reference: Blake, S., Wikelski, M., Cabrera, F., Guezou, A., Silva, M., Sadeghayobi, E., Yackulic, C. B. and Jaramillo, P. (2012), Seed dispersal by Galápagos tortoises. Journal of Biogeography, 39: 1961–1972.

Example of gigantism in response to absence of other herbivorous competitors

Evolved in absence of large predators

Mega fauna, act as ecosystem engineers equivalent in function to large mammals such as elephants

Prodigious seed dispersers, regularly moving large quantities of seeds over long distances.

Biology:

Reference: http://www.galapagosonline.com/Galapagos_Natural_History/Birds_and_Animals/Animals/Tortoises.html

Majority of time spent grazing in small groups

Migratory, between wet and dry season

The females dig nests in the ground for their eggs

A Species Under Threat:

References: http://www.cites.org/ http://www.iucnredlist.org/

Classified as Vulnerable (VU) on the IUCN Red List

Listed on Appendix I of CITES

Why is the Galápagos giant tortoise classified as vulnerable?

Over Exploitation:

Mariners and whalers in the 1600-1900s hunted them for meat and oil

Easy to catch due to lack of flight response

Took on board as many as 700 live animals – one tortoise could provide 200 pounds of meat.

Invasive Species:

Reference: http://www.galapagos.org/conservation/conservation/project-areas/ecosystem-restoration/

Invasive animals• Introduced livestock

• Introduced predators

In addition….

Invasive Plants• Invasive trees such as quinine have

transformed once treeless areas

Protection of Tortoises:

Hunting Ban:

Reference: http://www.galapagos.org/conservation/conservation/project-areas/ecosystem-restoration/

1936 international trade of tortoises was put under strict regulation

1970 capture and removal of any species from the Galápagos was banned

Entirety of the inhabited sections of the islands declared national parks

Captive Breeding:

Since 1965 tortoise eggs have been collected and raised in captivity

Provides protection from invasive predators

Eradication of Invasive Species:

Eradication of invasive goats: Use of tagged Judas Goats to locate herds Airborne gunners used to mass

exterminate goats

Reference: http://www.galapagos.org/conservation/conservation/conservationchallenges/invasive-species//

Eradication of invasive black rats: Removal of rats by deploying toxic bait via

helicopter Successful removal from multiple islands

including Pinzón 2014 1st successful wild reared tortoises

on Pinzón island in over 100 years

A Never Ending Battle:

Reference: Ehrenfeld, D. (2006), Transgenics and Vertebrate Cloning as Tools for Species Conservation. Conservation Biology, 20: 723–732

Further Protection from Invasive Species: New invasive species are still appearing e.g. Achatinidae sp.

Use of new Molecular Techniques: Consolidation of races of Galápagos tortoises as

subspecies / species

Restoring extinct races e.g. Chelonoidis nigra abingdonii – aka Lonesome George

C. n. abingdonii – Extinct as of 2012

1) Use in Biological Research:

Parent, C.E., Caccone, A., Petren, K., 2008. Colonization and diversification of Galápagos terrestrial fauna: a phylogenetic and biogeographical synthesis.

Played a major role in the origin of Charles Darwin's theory of evolution

Still used today as a model for island evolution

Continued Research into speciation in tortoises

Reference:

2) Ecological Function:

Largest native grazing species

Vital for maintaining plant communities

Produce depressions transforming the landscape

Reference: Blake, S., Wikelski, M., Cabrera, F., Guezou, A., Silva, M., Sadeghayobi, E., Yackulic, C. B. and Jaramillo, P. (2012), Seed dispersal by Galápagos tortoises. Journal of Biogeography, 39: 1961–1972.

3) Ecotourism:

References: Benitez-Capistros, F., Huge, J., Dahdouh-Guebas, F., Koedam, N., 2016. Exploring conservation discourses in the Galapagos Islands: A case study of the Galapagos giant tortoises

The Galápagos giant tortoise is a icon of ecotourism within the Galápagos

Over 90% of all the Galápagos’ income is from ecotourism

However ecotourism doesn’t benefit all local people

Conflicts heavily with agriculture

Any Questions?