Studying the Ecology and Distribution of the Invasive Treefrog

Studying the Ecology and Distribution of the Invasive Treefrog

Studying the ecology and distribution of the invasive treefrog Scinax quinquefasciatus

This project is currently Active

Fowler’s Snouted Treefrog (Scinax quinquefasciatus) is a relatively recent invader of the Galapagos Islands, having been introduced from mainland Ecuador, most likely during the wet El Niño season of 1997/1998.

Little is known about the biology and ecology of this frog in Galapagos. To close this knowledge gap and to gain information for potential management, CDF is carrying out a study of the diet, distribution, habitat use and potential dispersal of this species.

The CDF works on this project in collaboration with the Galapagos National Park Directorate and the Escuela Superior Politecnica del Litoral (ESPOL).

Our Research Team

Heinke Jäger

Principal Investigator

Heinke started working at CDRS in 1998, first on the introduced quinine tree ( Cinchona pubescens ) and then on rare and endangered plant species. After receiving her PhD from Technical University...

Read More

Jacqueline has been working at Charles Darwin Research Station as an entomologist since 2014. She is involved in several entomology projects in Galapagos and collaborated in the management of the...

Read More

Carolina Carrión Klier is a geospatial specialist at the Charles Darwin Foundation, where she started working in 2016. She received her M.Sc. in Environmental Sciences and Hydrology from the...

Read More

Other collaborators:

Marcelo Loyola (Project Assistant).

Project Details

The Fowler’s Snouted treefrog Scinax quinquefasciatus is a medium sized (33 – 38 mm) very adaptable frog species, native to western mainland Ecuador. It was probably introduced to the Galapagos Islands by means of cargo transfer in 1997/1998 during an exceptionally wet El Niño event. The unusual wet conditions during that period were thought to have facilitated the establishment of the species in the archipelago. The islands generally provide unfavorable environmental conditions for amphibians due to the lack of freshwater reservoirs or vast humid forest patches that are important for reproduction.

Fowler’s Snouted treefrog Scinax quinquefasciatus.
Fowler’s Snouted treefrog Scinax quinquefasciatus. Photo by: Raffael Ernst, Senckenberg Museum.

Presently, the treefrog has been reported from the islands of Santa Cruz and Isabela, and in the past, from San Cristóbal. While an attempt was made to control the species on Isabela, no updated information is available for Santa Cruz. It is important to know the distribution of this frog, its invasion potential and impact on native species in the islands to be able to formulate recommendations for management and quarantine decisions.

Our main goal is to improve the knowledge on the ecology and distribution of the invasive treefrog Scinax quinquefasciatus in an integrative approach, combining field-based assessments, lab-based dietary analyses and population genetic analyses.

The specific objectives of our project are:

  1. Knowledge about the distribution and abundance of the frog on Santa Cruz and Isabela (and possibly in San Cristóbal).
  2. Knowledge of the impact of the frog on the native fauna through depredation.
  3. Determine the origin of frog populations in Galapagos through genetic analysis.
  4. Determine the possible dispersion of the frog within the island and between islands.

Our results

Preliminary results show that the treefrog is widely distributed in the agricultural zone of Santa Cruz. Frog records outside the agricultural zone so far are located in Puerto Ayora and in transitional habitats towards the National Park are. The few records within the National Park area come from popular tourist sites, like Los Gemelos and Media Luna. Specimen obtained from the farm ‘Rancho Manzanillo’ were used for dietary analysis by means of gut content assessments. Preliminary results indicate that butterflies and moths (Lepidoptera) was the most frequently recorded insects. This is in line with field observations of frogs that aggregate at night around artificial light sources to feed on moths and other nocturnal insects attracted by the light.

The analysis is still in progress and is part of a thesis project linked to our collaborators from the ESPOL (Escuela Superior Politécnica del Litoral, Ecuador). Results about the dispersal risk between islands will be inform to quarantine efforts. We will also give management recommendations to the Galapagos National Park Directorate.

Keywords: Invasive frog, invasive species impacts, invasion potential, quarantine, dispersal potential

Bibliographical References

  • Döring, B., Mecke, S., Mader, F., Kaiser, H. (2016) A proposed optimal incision method to obtain gut contents from preserved anurans. Amphibia-Reptilia 37: 437-44.
  • Ernst, R., Massemin, D., Kowarik, I. (2011) Non-invasive invaders from the Caribbean: The status of Johnstone's Whistling frog (Eleutherodactylus johnstonei) ten years after its introduction to Western French Guiana. Biological Invasions 13: 1767–1777.
  • Hyslop J. 1980. Stomach contents analysis. A review of methods and their application. Journal of Fish Biology 17: 411-429.
  • Mieles, A., Bersoza, F. (2005) Composición de la dieta de Scinax quinquefasciatus (Fowler, 1913) (Anura: Hylidae) en la Isla Isabela: Laguna las Diablas. Estación Científica Charles Darwin, Área de Invertebrados, Puerto Ayora – Galápagos.
  • Phillips, B.L., Shine, R. (2004) Adapting to an invasive species: Toxic cane toads induce morphological change in Australian snakes. PNAS 101: 17150–17155
  • Phillips, R.B., Wiedenfeld, D.A., Snell, H.L. (2012) Current status of alien vertebrates in the Galápagos Islands: invasion history, distribution, and potential impacts. Biological Invasions, 14(2), 461-480.
  • Rödel, M.-O., Ernst, R. (2004) Measuring and monitoring amphibian diversity in tropical forests. I. An evaluation of methods with recommendations for standardization. Ecotropica 10: 1-14.
  • Snell, H.L., Rea, S. (1999) The 1997-98 El Niño in Galápagos: can 34 years of data estimate 120 years of pattern? Noticias de Galápagos 60: 11-20.
  • Vintimilla, J.E. (2005) Estudios para el control y disminución de ranas Scinax quinquefasciatus, con impactos mínimos en los Humedales de Isabela Sur (Islas Galápagos). Tesis previa la obtención del título de Ingeniero Agrónomo. Universidad de Cuenca. Cuenca, Ecuador, 71pp.
  • Zug, G. R. (2013). Reptiles and amphibians of the Pacific Islands: a comprehensive guide. University of California Press.
  • Zurita, L. (2004) Estudios para el control de la rana S. quinquefasciatus en las pozas de Isabela Sur por incremento de salinidad. Tesis de pregrado, Fundación Charles Darwin, Galápagos.

Current Donors

Galapagos ConservancyLindblad Expeditions-National Geographic Fund, Basler Stiftung für biologische Forschung.

The “Charles Darwin Foundation for the Galapagos Islands”, in French “Fondation Charles Darwin pour les îles Galapagos”, Association International sans but lucratif (“AISBL”), has its registered office located at Drève du Pieuré 19, 1160 Brussels, and is registered under the trade registry of Brussels under the number 0409.359.103.

© 2019 Charles Darwin Foundation. All rights reserved.