La Gomera giant lizard (Gallotia bravoana)

Description

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La Gomera giant lizard fact file

• Description
• Biology
• Range
• Habitat
• Status
• Threats
• Conservation
• Find out more
• Glossary
• References
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La Gomera giant lizard description

Historically known only from partially fossilised bones, the fascinating La Gomera giant lizard (Gallotia bravoana) was thought to be extinct until the discovery of a number of living specimens in 1999 ^{(1) (2)}. All members of the genus Gallotia are endemic to the Canary Islands, with a number of species in this genus having only been discovered in recent years ⁽⁴⁾.

As with other species of giant lizard from the Canary Islands, the La Gomera giant lizard is a large and robust species ⁽⁵⁾. The adult is blackish-brown along the back, with two rows of blue eye-like spots along its sides ⁽²⁾. Its underside, including the legs and tail, are ivory white ⁽²⁾. The scales of the legs are black, smooth and irregular. The female La Gomera giant lizard differs from the male in being browner on the back and legs, and also generally smaller ⁽²⁾. Additionally, the male has a larger head and a white throat ⁽³⁾. The La Gomera giant lizard has yellowish-orange eyes with black pupils ⁽²⁾.

The juvenile La Gomera giant lizard is generally brownish-grey, with the underside usually cream with some green tones. Its back and sides are patterned with a mixture of black spots, cream lines and multiple rows of blue spots, which vary in shade ⁽²⁾.

Synonyms

Gallotia gomerana.

Spanish

Lagarto Gigante de La Gomera.

Size

Snout-vent length: 13.5 - 19 cm ⁽²⁾

Total length: 29.5 - 49 cm ⁽²⁾

Weight

up to 500 g ⁽³⁾

La Gomera giant lizard biology

An extremely rare species, what little is known of the biology of the La Gomera giant lizard has been learned from the small, captive populations. It is known to be diurnal, with activity beginning around mid-morning and ending in the late afternoon ^{(1) (6)}. This species will spend its day basking and foraging for food, with activity levels becoming reduced in the hottest months of the summer. It is mainly herbivorous, although sub-adults are known to include a greater portion of insects and insect larvae in their diets than adults ⁽⁶⁾.

Courtship behaviour of the male La Gomera giant lizard consists of a head-bob display, where the male will inflate its throat and move its head up and down in the presence of a female. Courtship in captive animals typically occurs during July, but has also been observed between the end of June and mid-September ⁽⁶⁾.

The La Gomera giant lizard is an egg-laying species, with the female excavating a nest site in which between three and seven eggs are laid ^{(1) (3)}. A single clutch is produced each year ⁽¹⁾.

La Gomera giant lizard range

As with all other members of the genus Gallotia, the La Gomera giant lizard is endemic to the Canary Islands, with this species only occuring on the island of La Gomera ⁽¹⁾.

Although this species is thought to have had a much larger range in the past, it is now restricted to just two inaccessible cliffs close to Valle Gran Rey, on the west of the island ^{(1) (2)}. The total range of the La Gomera giant lizard is thought to total less than one hectare ⁽¹⁾. 

La Gomera giant lizard habitat

Historically, the La Gomera giant lizard is thought to have occupied a number of habitat types across the island of La Gomera. However, this species is now restricted to dry cliffs with sparse vegetation ⁽¹⁾. Fallen volcanic boulders make up the substrate of the area and the vegetation is the typical xeric (dry) shrub of the Canary Islands ⁽²⁾.

La Gomera giant lizard status

The La Gomera giant lizard is classified as Critically Endangered (CR) on the IUCN Red List ⁽¹⁾.

La Gomera giant lizard threats

As with many island-dwelling species, the La Gomera giant lizard is threatened by predators introduced to its habitat by humans, such as rats and cats ⁽²⁾. Hunting by humans and overgrazing of its habitat by domestic livestock have also exacerbated this species’ decline ⁽¹⁾. Due to the small, fragmented nature of the remaining La Gomera giant lizard population, it also at risk from chance natural events such as rock falls ⁽¹⁾.

La Gomera giant lizard conservation

The remaining population of the La Gomera giant lizard is thought to number only around 90 wild individuals ⁽¹⁾. This species is currently protected by international legislation, and the majority of its range occurs within the protected rural park of Valle Gran Rey ^{(1) (7)}.

A species recovery plan for the La Gomera giant lizard has been implemented, which aims to increase the population size and ensure its viability in the wild by removing its major threats ⁽⁸⁾. The captive breeding of this species has so far proved successful, more than doubling the population. Measures have also been taken to remove predators, such as feral cats, from the remaining La Gomera giant lizard habitat ⁽⁸⁾.

Ongoing conservation efforts for the La Gomera giant lizard include a public awareness campaign and the search for other isolated, remnant populations. The final aim of conservationists is the release and reestablishment of this species in its natural habitat ⁽⁸⁾.

View information on this species at the UNEP World Conservation Monitoring Centre.

Find out more

Find out more on the conservation of the La Gomera giant lizard:

• Recovery Plan for the Giant Lizard of La Gomera:
  http://ec.europa.eu/environment/life/project/Projects/files/laymanReport/LIFE02_NAT_E_008614_LAYMAN.pdf

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Glossary

Diurnal

Active during the day.

Endemic

A species or taxonomic group that is only found in one particular country or geographic area.

Genus

A category used in taxonomy, which is below ‘family’ and above ‘species’. A genus tends to contain species that have characteristics in common. The genus forms the first part of a ‘binomial’ Latin species name; the second part is the specific name.

Herbivorous

Having a diet that comprises only vegetable matter.

Larva

Immature stage in an animal’s lifecycle, after it hatches from an egg and before it changes into the adult form. Larvae are typically very different in appearance to adults; they are able to feed and move around but are usually unable to reproduce.

References

1. IUCN Red List (October, 2011)
   http://www.iucnredlist.org/
2. Nogales, M., Rando, J.C., Valido, A. and Martín, A. (2001) Discovery of a living giant lizard, genus Gallotia (Reptilia: Lacertidae), from a Gomera, Canary Islands. Herpetologica, 57(2): 169-179.
3. Hernandez-Divers, S.J., Lafortune, M., Martinez-Silvestre, A. and Pether, J. (2003) Assessment and conservation of the giant gomeran lizard (Gallotia bravoana). Veterinary Record, 152(13): 395-399.
4. Afonso, O.M. and Mateo, J.A. (2003) Los lagartos gigantes canarios: conservación creativa de poblaciones mínimas. In: Jiménez, I. and Delibes, M. (Eds) Al Borde de la Extinción: Integrando Ciencia, Política y Sociedad en la Recuperación de Especies Amenazadas. Evren, Valencia. Available at:
   http://www.sehumed.es/banco/archivos/bordeextincion.pdf
5. Mateo, J.A. (2009) Lagarto gigante de La Palma – Gallotia auaritae. In: Enciclopedia Virtual de los Vertebrados Españoles. Carrascal, L.M. and Salvador, A. (Eds.) Museo Nacional de Ciencias Naturales, Madrid. Available at:
   http://www.vertebradosibericos.org/reptiles/pdf/galaua.pdf
6. Mesa-Avila, G. and Molina-Borja, M. (2007) Behaviour as a tool for welfare improvement and conservation management in the endangered lizard (Gallotia bravoana). Journal of Applied Animal Welfare Science.  10(3): 193-206.
7. Recovery Plan for the giant lizard of La Gomera: Informative Report (Action E.9) (October, 2011)
   http://ec.europa.eu/environment/life/project/Projects/files/laymanReport/LIFE02_NAT_E_008614_LAYMAN.pdf
8. Lagarto Gomera - Recovery plan for the giant lizard of La Gomera (October, 2011)
   http://ec.europa.eu/environment/life/project/Projects/index.cfm?fuseaction=search.dspPage&n_proj_id=2001&docType=pdf