Science and Research, Volunteers and Visitors

Golfo Dulce Poison Dart Frogs

Submitted by Steven Waldron; Seattle, WA

Twenty years ago, I backpacked and hiked along the wild beaches and coastal rainforests of the Osa peninsula and became acquainted with some of the fantastic wildlife that the region is well-known for. Near the Sirena station at Corcovado National Park, I became intimate with the loud squawks of Scarlet Macaws sailing overhead, the crash of surprised tapirs bolting through the forest, and the pre-dawn chorus of Howler monkeys. One of the sensory aspects I appreciate most about exploring this region is the rich array of sounds that greets the rainforest naturalist. The forests of the Osa are alive with every kind of exotic screech, hoot, cry, whistle and howl. However, there was one voice that alluded me during that first trip many years ago; that of a little poison dart frog unique to the region, Phyllobates vittatus, the Golfo Dulce poison dart frog. Though the call of Phyllobates vittatus was certainly in the mix of the rainforest cacophony that greeted me back then, I just didn’t know how to identify it and discover its secrets within the complex mystery of the jungle matrix. On a recent trip to the Cabo Matapalo region, I was focused on encountering this beautiful red/black/green jewel of a frog and to document some of its natural history and beauty in photos.

From my research, I knew that Phyllobates vittatus is endemic to southwestern Costa Rica and found from Domincal in the north to (likely) the Boruca peninsula in the south. Due to its limited distribution, P. vittatus is listed by the IUCN as an endangered species. P. vittatus is known to inhabit primary forest microhabitats near streams; it’s diurnal and dwells in the leaf litter of the forest understory. Phyllobates vittatus is one of the true poison dart frogs with another sister species found in the Caribbean slope of Costa Rica and Panama (Phyllobates lugubris) and three other known relative species in the Chocó rainforest of Colombia (Phyllobates aurotaenia, Phyllobates bicolor and Phyllobates terribilis). The evolutionary links to the Chocó appear to be a common theme in Osa natural history.

19881843978_7859cdbac4_oDuring our first day in the Matapalo forest, my wife and I went for a late afternoon walk along a perennial creek with a rocky stream bed covered in fallen leaves. It seemed like the ideal habitat for Phyllobates vitiates, and it was! My wife found our first Phyllobates vittatus hanging out in a sheltered spot below a fallen log. Interestingly, I found this very frog in the same spot during my informal surveys over the course of the next week. P. vittatus appears to be fairly territorial in its habits. As the night was approaching quickly, my wife and I decided to resume our Phyllobates search for the following morning. A few hours after the next dawn, we were rewarded with the discovery of several vocalizing males singing from the creek banks. Luckily, I was able to photograph the frogs in their microhabitat and witnessed several courting male/female pairs.

Despite their toxic nature and bold coloration, P. vittatus is a fairly shy frog that is more often heard than seen. Once you learn the song of this frog, you realize that they are locally abundant in the Osa forests. However, the calling males will usually quickly fall silent and retreat into rock crevices or leaf litter when they feel threatened or discovered. Without this interruption, the typical reproduction process would proceed as follow:

The male P. vittatus serenades the female as she looks on. If all goes well, and both parties are mutually interested, the pair will retire to a sheltered spot in the fallen leaves where they will lay 7 to 21 eggs. The eggs will hatch in a couple of weeks; during that time period the male will periodically return to the developing embryos and moisten them with water shed from a specialized patch of vascularized tissue on his posterior. When the tadpoles hatch, they will then be visited by their father, climb onto his back and he will hop off into the forest to find a small pool of water for them to complete their development into little frogs some forty-five days later.

As our days of birding, botanizing and frogging unfolded during our relaxing week in Cabo Matapalo, the song of Phyllobates vittatus was a constant companion as it greeted us cheerfully from nearly every creek, spring and stream bed along the forest trails we visited. I came to look forward to hearing it as much as I enjoyed the raucous call of the macaws, the screech of the parakeets, the complaints of monkeys and the crashing of waves along the wild beaches. I realized that Phyllobates vittatus presence in these forests is a small but critical voice in the rich tapestry of biodiversity that gives southwestern Costa Rica its unique and charming character.

Marine Conservation, Science and Research

Osa Conservation Supports Research in Golfo Dulce: A Humpback Whale Hotspot

These three photos show a baby Humpback whale next to its resting mama – TOP: nursing; MIDDLE: breathing; and BOTTOM: spyhopping

A variety of whale species may be found in the eastern Pacific Ocean off the coast of Costa Rica, including Byrde’s whale (Balaenoptera edeni), Fin whale (Balaenoptera physalus), Sperm whale (Physeter macrocephalus) and Killer whale (Orcinus orca). But the most commonly seen whale inside the Golfo Dulce is the Humpback whale (Megaptera novaeangliae), a species that annually migrates from colder feeding grounds near the magnetic poles to warmer equatorial breeding and birthing grounds.

In fact, the area around the Osa Peninsula is a really special place for Humpbacks — it is the only known place in the world where the migration paths of whales from both the northern and southern hemispheres cross over. Because the Arctic and Antarctic seasons are opposing, Humpbacks from the North Pacific Ocean spend time inside the Golfo Dulce during January and February while Humpbacks from the Southern Ocean normally arrive during July and August. That means whales are coming and going from the gulf throughout much of the year.

We logged 25 Humpbacks during our surveys, mostly mothers with young calves. The whales were often seen traveling up into the embayment, possibly seeking sanctuary from the open sea. We even witnessed a baby Humpback nursing — an experience Jorge and I will never forget! That sighting plus birthing events reported to us during both seasons suggest that embayment may even be a haven for Humpback nativity. Isn’t that remarkable? Indeed, the more we learn about the role the Golfo Dulce plays in the whales’ ecology, the more important it appears.

It is incredible to think how far Humpback whales travel to visit the Golfo Dulce and we can only hope the calm gulf waters will always offer those gentle titans safe retreat at the end of their long journey.

Brooke Bessesen conducted Marine research at the Osa in 2010 and 2011 as a recipient of the Greg Gund Memorial Fellowship. Check out her Golfo Dulce report on our website.

Community Outreach, Environmental Education

Water Workshops on the Osa Peninsula Protect Aquatic Ecosystems

In October, Friends of the Osa’s Environmental Education program, working with ACEPESA (Central American Association for the Economy, Health and Environment), started conducting workshops in the community of La Palma, Costa Rica.  These workshops are designed to raise awareness about appropriate water management and are part of a larger project, “Capacity building in coastal communities of the Golfo Dulce to improve sanitation conditions.”

The objective of this project is to contribute to community awareness about the responsible use of water resources and the proper management of wastewater through the construction of bio-boxes as a mechanism for treatment of gray water.

Workshop topics are: 1. Water and its importance to human life and ecosystems, 2. Water and watersheds, 3. Mangrove ecosystems, 4. Golfo Dulce ecosystem, 5. Global warming and its impacts, 6. Water and its effect on health and the environment, and 7. Alternative sanitation and rainwater harvesting.

This project is relevant to the conservation of the Osa Peninsula’s aquatic resources including rivers, mangroves and the Golfo Dulce, helping to mitigate pollution and deterioration of these vital ecosystems.

Find out more about Friends of the Osa and our other conservation work on the Osa Peninsula by visiting our website, or plan a trip to the Osa Biodiversity Center.

Environmental Education, Marine Conservation, Sea Turtles

Raising Awareness About Sea Turtle Conservation and Marine Ecosystems of the Osa

Friends of the Osa’s Environmental Education program is carrying out educational activities on the conservation of sea turtles and marine ecosystems in the schools of the Osa Peninsula.

The objectives are for students to learn the importance of sea turtle conservation, why Golfo Dulce is a tropical fjord, and the ecological and scientific implications of this designation.

Students learn about the four sea turtle species that nest every year on the beaches of the Osa Peninsula: Olive Ridley (Lepidochelys olivacea), East Pacific Green or black turtle (Chelonia mydas agassizii), Hawksbill (Eretmochelys imbricata) and Leatherback (Dermochelys coriacea). They also learn about the nesting process, migration, life cycle, threats and efforts being made in the conservation of these species.

Marine Ecosystems Section of the Environmental Education Program
Students learn about the Osa Peninsula’s marine ecosystems

The topographical features of the Golfo Dulce, major ecosystems, both resident and non-resident species, such as humpback whales and the environmental impacts on ecosystems, are topics that are treated within the marine ecosystems program.

This section of the Environmental Education program seeks to foster student interest in understanding this unexplored area within the school curriculum, which has traditionally focused only on terrestrial ecosystems.

It’s really interesting for students to learn about species previously unknown to them, such as marine plankton, species that make aquatic ecosystems sustainable and contribute between 50-90% of the oxygen to the Earth’s atmosphere.