Volunteers and Visitors

Treefrog Breeding Frenzy!

Cesar Barrio-Amoros holds a PhD in biology and is a notable taxonomist, herpetologist, author, and photographer. Following his experience in the Osa, reflected below, Cesar has planned to lead a reptile and amphibian workshop at Piro Biological Station next May or June, the beginning of the wet season.

I have traveled throughout most of Latin America in search of amazing herping spectacles. In the Galapagos, I saw marine iguanas (Amblyrhynchus cristatus) and Galapagos giant tortoises (Chelonoidis nigra). I witnessed an astonishing diversity of poison frogs in Peru and made some interesting scientific discoveries on the Tepuis of Venezuela. My curiosity has now led me to one of the tiniest countries: Costa Rica. Here, the herpetological diversity is bewildering and vibrant. Due to Costa Rica’s intense biodiversity, it is not difficult for a photographer to capture nearly all of the herping species in a matter of years.

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The gliding treefrog (Agalychnis spurrelli) was on the top of my herping list after learning about it on a BBC documentary. I have actually seen the individual species in the Caribbean and Pacific lowlands. However, I never saw one of those impressive reproductive aggregations where thousands of frogs gather in a pond and lay millions of eggs in just a few nights.

I was envious of the photographs my colleague, Manuel Sanchez, captured while working at Osa Conservation’s Piro Biological Station in the Osa Peninsula. I immediately scheduled a visit to see the event. When I arrived, Manuel informed me that the area was full of frogs, thousands were laying eggs in amplexus (amplectant pairs).

Around 6:00AM the next morning, we left for our journey along with herpetologist intern and researcher, Michelle Thompson. At the site, we noticed some bushes moving and, upon further investigation, realized there were a few frogs still laying eggs. The great wave was the previous night so only about 10% frogs remained.

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Still, it was a breathtaking sight because they were completely surrounded by millions of eggs! Michelle and I were amazed — this was quite an experience for a herpetologist. Next time, I need to arrive a few days in advance in order to catch the whole spectacle!

Science and Research, Volunteers and Visitors

Visitors at the Osa Biodiversity Center in 2009

Three different student groups visited the OBC last year: The Herpetology classes of the University of Costa Rica and Universidad Nacional led by professors Federico Bolaños and Marco Barquero, plus the Natural History and Zoology classes of the Universidad Latina, led by professor Luis Sandoval.


visitors02The Guides and Scouts of Puerto Jiménez, joined by a troop from Pérez Zeledón, went to the OBC to put in practice their camping skills for the first time, in an improvised camp set up by the children.


A group of forestry engineers from the Cartago Technological Institute, in partnership with CATIE and the University of Connecticut, established a series of plots in the surroundings of the OBC to determine forest structure at different stages of succession and document carbon sequestration.


Adrián García, working with bioacoustics in amphibians, has visited the OBC several times to record the songs of various species. His research is part of a project funded by an Evergreen grant.


Stuart Jeckel, of the University of North Carolina, was in the OBC in search of the Túngara frog Engystomops pustulosus, as he is studying their breeding behavior at the neural level.


Guido Saborio keeps impressing volunteers at OBC. He received this message from one of them who spent three weeks at the center:

Dear Guido,
Thank you so much for everything. Our time at the OBC was an absolutely amazing experience; we learned so much and met so many new, interesting people. It also was very helpful to me in realizing what I want to study in college, because I remembered how much I like plants and how interesting botany is for me. Thanks so much for everything you taught us!

-Brook Theis


Karen Masters brought a student group to Cerro Osa for their Sustainability and the Environment course.  They inaugurated the new camping platforms and composting latrines.visitors03