limestone frogs and geckoes of gigantes islands: status of population and habitat

Limestone Frogs and Geckoes of Gigantes Islands

Status of Population and HabitatArvin C. Diesmos

Scientist 3National Museum of the Philippines

Chair, Amphibian Specialist Group PhilippinesIUCN Species Survival Commission

Thank You!• Foundation for the Philippine Environment • West Visayas Caving Association • Local Government Units (Carles, Estancia, Iloilo City) • DENR • Biodiversity Management Bureau • Fauna & Flora International • National Museum of the Philippines • Prof. Angel Alcala • Dr. Rafe Brown • Dr. Aldrin Mallari • Marlynn Mendoza • James Lewis (IUCN)

Outline

• What is a limestone karst ecosystem • History of research in the Philippines • Biodiversity in limestone karst ecosystems • Gigantes Islands • Initial Results • Recommendations

Limestone Karst

Limestone karst formations

Limestone Karst

Occupies 10% of land area

Threats

Intensive and extensive kaingin farming.Image by AC Diesmos, San Mariano, Isabela Province, Luzon, 2006.

Threats

Image from flickr.com/photos/storm-crypt/.

Destructive mining is the greatest threat to limestone karst habitats.

Initial Results

Gigantes Island Group

Gigantes Island Group

Mallari et al., 2001; Conservation International, Haribon Foundation, DENR, 2010

• Comprised of nine islands in central Philippines• Almost all islands are limestone karst• Largest: 599 ha• Almost all islands are limestone karst• Key biodiversity area; with endemic species

Brown and Alcala., 1976; IUCN, 2014; Diesmos et al., 2014; image by A.C. Diesmos (2014)

Gigantes Limestone Gecko Gekko gigante.This species is considered Vulnerable.

Brown and Alcala., 1970; IUCN, 2014; Diesmos et al., 2014; image by A.C. Diesmos (2014)

Gigantes Limestone Frog Platymantis insulatus.This species is Critically Endangered.

Field Surveys• Surveyed nine islands, total of 16 sites• 13 limestone caves• Survey of herpetofauna• Performed cave assessments• Established strip transects (10 meters wide x 100 meters long)• General survey were under taken by visual

and aural method

Field surveys include herpetofaunal surveys and cave assessments.

image by A.C. Diesmos (2014)

Field surveys include herpetofaunal surveys and cave assessments.

image by A.C. Diesmos (2014)

• Treasure hunting• Collection of speleothems

Threats to Caves of Gigantes

• Graffiti or vandalism• High human foot traffic or tourism

• Presence of garbage/litter• Mining of guano

Treasure hunting is the greatest threat to the cave systems of Gigantes.

image by A.C. Diesmos (2014)

Half of the caves bore high levels of vandalism.image by A.C. Diesmos (2014)

Initial Results• Platymantis insulatus and Gekko gigante still

found in several areas in GIG. • Populations appear secure for both species.• Both species more widely distributed than previously thought.• Both species maybe tolerant to disturbance.

Recommendations

• Long term ecological studies are needed: let us monitor subpopulations• Cave management and action plan!

• Community based management!