Hidden Treasures: The Search for Caves on the Osa Peninsula

Blog Post by Stanimira Deleva, Alvaro Ugalde Scholarship Awardee

The Osa Peninsula is a place where, even after hundreds of exploratory expeditions, there is always something to be discovered. As one of the world’s most biodiverse sites, the Osa is home to a vast variety of bats, most who use caves as a refuge, that have not yet been fully explored. I first visited the peninsula in 2015 to study the bats. Several of the bats that we caught in mist nets were cave-dwellers. I wondered where these bats live, since no caves are officially known on the peninsula. There were two options: bats have either changed their ecology, or there are caves we don’t know about. As a specialist on cave-dwelling bats, I was intrigued by this question and started to plan a cave exploration expedition on the Peninsula. I knew that discovering large cave systems in Osa was unlikely because of the lack of limestone that rock caves are generally comprised of, but my experience in Costa Rica showed me that small volcanic or sea caves can be as populated with bats as large caves and just as interesting.

In front of the entrance of Catatatas Cave near San Josecito.

This year, thanks to the strong support of Osa Conservation, I was able to search and explore caves and other underground habitats on the Peninsula. I had previously identified several sites for searching, like an interesting old gold mine near La Palma. The landowner informed us about the mine when he found out that we were looking for caves, so we paid a visit this February. We managed to create a map of the interior parts, and marked bat colonies instead of gold treasures. For several hours in the cave, we described the specific features of the relief and microclimate and discovered that the cave was over 200 meters long and branched like a maze.  We also found two species of bats and an extremely rich invertebrate fauna.

The narrow entrance of the old coal mine.


Mapping the gold mine.


Goose barnacles discovered in one of the marine caves.

Next, we searched for sea caves on the west coast of Osa. On previous trips, we had known that these sea caves existed there, but we had not mapped them. So, after a few hours of hiking from the San Josecito beach, we set out to explore three caves. The cave near the Campanario research station shelters one of the biggest colonies of mustached bats in Costa Rica with several thousands of individuals from three species!

Exploring a marine cave.


A bat colony in the marine cave.


Exploring marine caves in Isla Violin.

I found out from local people about a cave on Isla Violin. This island is hard to reach, but I managed to organize a visit, thanks to the people at Violin EcoLodge who helped me with the field expedition and took us to the cave by boat. The “cave” turned out to be an abandoned gold mine once again. And this time we were fascinated by the variety of bats we found—over 500 bats of 6 different species! Difficult access to the cave has kept the bats undisturbed from any raiders. On the floor of the cave, we noticed many invertebrates. During this expedition we found another cave on the island, located on the seashore. We rode horses to cross the island because our boat could not stand against the intense waves around the beach. After reaching the beach, we had to compete with the coming tide by jumping between waves and climb several boulders in order to reach the sea cave. Finally, we found the cave, but alas, there were no bats. We made a sketch and left, racing with the coming tide.

The boat ride through the mangroves was an adventure on its own.


Bats in the Isla Violin cave.

Crossing the island on horseback.

Our next plans are to explore the southern part of Osa around Sirena station, where we learned of another promising bat cave. We hope to find other hidden treasures!



Creating the First Conservation Action Plan for the Golfo Dulce Poison Dart Frog

Blog Post By Marina Garrido, Restoration & Rewilding Program Assistant

As one of the assistants of the Restoration & Rewilding Program, I am happy to announce a new project entitled “Creating the First Conservation Action Plan for the Endemic and Endangered Golfo Dulce Poison Dart Frog using Citizen Science and Tiny-Tech.”

Phyllobates vittatus posing perfectly for Robin Moore´s camera lens at Osa Conservation’s Biological Station. Photo taken from the book In Search of Lost Frogs by Robin Moore.

Many of you might be wondering, what makes the Golfo Dulce Frog special so as to have its own project?” Well, there are many fascinating qualities of this species. This beautiful little frog, Phyllobates vittatus, is endemic to the area and is a flagship species to the Osa. It is a unique frog from the genus Phyllobates, and is the cousin of one of the most poisonous frogs, Phyllobates terriblis. Despite how charismatic this species is, it is highly endangered, and no conservation efforts are currently underway. The Golfo Dulce Frog is threatened by habitat loss, water contamination and illegal pet trade. Limited research has been conducted on this endangered species, and a conservation action plan has never been developed, until now.

With this project, I aim to create the first conservation action plan for this tiny frog. In order to do so, the current main objectives are:

  1. Enhancing scientific knowledge of the species’ ecology.
  2. Determining the current and past distribution of the species throughout the Osa in collaboration with citizen scientists.
  3. Identifying key areas for habitat protection, habitat restoration, and population translocations.
  4. Improving long-term local conservation leadership by raising awareness about the value of this species and building the scientific skills and knowledge of local citizen scientists.

In the first phase of this project, I completed expeditions along the Peninsula, searching for populations of Golfo Dulce Frogs. I traveled to different areas of the Osa, visiting partners like Saladero Ecolodge, Los Pargos, and Lapa Ríos Ecolodge. I have also been studying a stable frog population in a known area, checking every morning for individuals and following them for some hours. In this way, I have found some  interesting and rather surprising male-male and male-female behaviors and interactions.

Female Phyllobates vittatus. Photo by Marina Garrido.

The Osa Peninsula marks where the rainforest meets sea, with streams connecting these two valuable ecosystems. The diverse tropical forests of the Osa are not only inhabited by the Golfo Dulce Frog, but many other unique species as well. Therefore, conserving forest and riparian habitats through the protection of the Golfo Dulce Frog will also provide protection for the vast array of species here.

Marina Garrido with Phyllobates vittatus. Photo by Marvin Sánchez.

Fortunately, this project is starting to catch people’s attention, and I have been grateful to receive funding from Alongside Wildlife Foundation. Little by little, it will be possible to create a suitable conservation action plan to protect the Golfo Dulce Frog for generations to come.

There will be many updates to come as the plan to preserve the Golfo Dulce Frog develops, so be sure to stay tuned to learn more about this beautiful frog, this project, and how you can lend your support!


Fresh Perspectives on Freshwater

Blog Post by Avery Kaplan, Rios Saludables Intern

One sunny day this summer, the Ríos Saludables team was wading through the rivers Agujas, La Palma, Montarey, and Sabalo, collecting shrimp traps number 122 through number 132. It was the third time in three months that we had set and collected traps all along these rivers, and we were back the second time that week to check on the traps that we had set the day before. In other words, sometimes even the best field work gets repetitive.

The Ríos Saludables team in Río Agujas, from left to right: Hilary Brumberg, Keje Nagel, and Avery Kaplan.

Out of the ordinary though, we started off the day at a sustainable farm in La Palma to pick up Alex, the coordinator of the Osa palm farmers’ cooperative and one of Ríos Saludables’ local river monitoring partners, and Brian, the Peace Corps volunteer working with him. Alex has participated in many Ríos Saludables expeditions before, and was excited to see the new multiparameter probe we were using to take water quality measurements.

Avery, an Osa Conservation intern, and Brian, a Peace Corps volunteer, using the multiparameter probe to get conductivity, salinity, dissolved oxygen, and temperature measurements at a trapping site.

As we walked through the straight rows of palm plantation down to the first collection site in Río Agujas, we explained to the new volunteer why we were trapping shrimp: Osa Conservation is conducting the first ever study of giant freshwater shrimp in the Osa Peninsula to understand whether diversity is affected by the type of land-use adjacent to the river. Shrimp are a good indicator species because they migrate throughout rivers, making their abundance a reliable measure of river health.

Walking to a river that cuts through palm plantation. Plantation is one of four land use types we are studying. The others are grassland, old growth forest, and secondary forest.

After arriving at the first site and taking water quality and canopy measurements, we pulled the shrimp trap from the river to see what we would find. As we took shrimp out of the trap, being careful to avoid their pinchers, seeing the shock on Brian’s face at the size and variety of shrimp reminded me just how extraordinary these creatures are. They range from less than a gram to more than 70 grams, can be bright blue or perfectly camouflaged, and—due to anthropogenic impacts (such as deforestation and river poisoning)—are becoming a rare sight to see.

A Macrobrachium americanum, patiently waiting to be identified. Similar to the design of a minnow trap, this homemade shrimp trap is made from upcycled wood, bottles found on the beach, and mesh.

On the walk to the next trapping site, Alex spotted a boa in a palm tree. A little later, he disappeared into the brush and returned with a cacao fruit for us to snack on. Between Alex’s keen experienced eyes, and Brian’s fresh ones, I saw more that day in the field than I ever would have expected.  Every day in the Osa is an adventure, with much to learn.

The boa hidden in a palm tree. Can you spot it?


Animal behavior: Osa’s ‘magic well’

Blog Post by Dr. Mark Laidre, Assistant Professor of Biological Sciences at Dartmouth College

Few things are more fascinating to layperson and scientist alike than animal behavior. For some, this simple fascination can ultimately fuel a lifelong passion for discovering why animals do what they do. Perhaps no better example is the Nobel Prize-winning biologist Karl von Frisch, who, as one of the founding fathers of animal behavior, spent decades studying the social behavior of bees. It may at first seem puzzling how someone could devote such prolonged study to just one critter, but von Frisch explained it quite easily, remarking: “The bee’s life is like a magic well: the more you draw from it, the more it fills with water.” And so too for countless creatures: the more we learn about their behavior, the more new and exciting questions it raises, which keeps us coming back for more.

The tropics is an unsurpassed place for such intellectual seeds to flourish. In 2008, I first stepped foot in Osa, just as Osa Conservation was opening its field station. And I’ve been coming back to the Osa nearly every year since, first as a graduate student, then a postdoc, and later a professor, with 2018 now marking a full decade of studies in the Osa (hopefully with many more visits to Osa still to come during the ensuing decades!). Each year I return to the Osa, I fall in love with its amazing wildlife once again. Most of my time is spent studying social animals, ranging from ants to birds to primates. But it is Osa’s most abundant and dominant beach denizens—the terrestrial hermit crabs (Coenobita compressus)—which have been the object of my scientific obsession since 2008.

Laidre lab at Osa Conservation’s Biological Station. From left to right: Dr. Louise Roberts (postdoc), Leah Valdes (honors thesis undergrad), Clare Doherty (PhD student), Mark Laidre (PI), Elliott Steele (PhD student), and Dr. Jakob Krieger (visiting scholar).

These ‘social hermits’ have an especially complex social life, one which revolves around a housing market of architecturally remodeled homes, passed down across generations as an extra-genetic inheritance. In contrast to social insects (e.g., the bees von Frisch studied), which mostly live among close genetic kin, social hermits live together in what is effectively a vast city of non-kin. Among these unrelated individuals, there is a constant tension between conflict and cooperation, which permeates the very core of their societies. This social drama, combined with these animals’ unusually rich behavioral repertoire and amenability to field experiments, provides a fascinating system reflecting the evolution of social life. Indeed, social hermit crabs never cease to reward curiosity and persistence with further exciting scientific discoveries.

Social group of terrestrial hermit crabs (Coenobita compressus) on Osa beach.

This past field season was no exception. From January to March 2018, myself and five members of my lab from Dartmouth continued to dig deeper into the social lives of these amazing animals. Our experiments over several months spanned the intellectual gamut from the architectural foundations of social privacy; to the evolutionary loss of displays; to ecological constraints on vision; to massive chemically-mediated funeral celebrations; to coded messages sent via substrate-borne vibration through the beach sand. During August 2018, at the International Society for Behavioral Ecology, we presented scientific talks on these studies, including:

  • ‘Scent of death: how and why is conspecific death attractive?’ (Leah Valdes)
  • ‘Evolutionary loss of a threat display: from antisocial to social living’ (Clare Doherty)
  • ‘Leaf me alone: visual constraints on the ecology of social grouping’ (Elliott Steele)
  • ‘Get off my back: vibrational assessment of resource holding potential and ownership’ (Louise Roberts)
  • ‘Exclusive social circles: the construction of privacy’ (Mark Laidre)

The many fascinating questions that can be addressed with social hermit crabs reinforces von Frisch’s important point about the ‘magic well’: the magic arises through continued focused study of a particular organism, ultimately enabling deep insights into a topic of fundamental interest. In our humble opinion, the best recipe for science is therefore simply letting an inherent pleasure in discovering new things about nature drive ever deeper exploration of one’s favorite magic well. And Osa is perhaps the most magical well one can imagine for discovering new things about nature. Hope we’ll bump into you there during our next field season.


Conserving the last populations of the Golfito Robber Frog

Blog Post by Hector Zumbado-Ulate, Alvaro Ugalde Scholarship Awardee

My name is Hector Zumbado-Ulate and I’m one of the awardees of Osa Conservation’s Alvaro Ugalde Scholarship. Currently, I am pursuing a PhD in ecology and evolutionary biology at Purdue University. Since I started my studies in biology, I felt very attached to amphibian conservation projects, especially those helping species which are currently endangered by anthropogenic causes. For that reason, I wanted to work with the critically endangered Golfito robber frog. Specifically, I want to examine why this species persists in remnant populations after going extinct in much of their historical home range. Such information is valuable to develop adequate conservation policies that can be implemented to protect these populations and encourage their expansion back into their historical habitat range throughout Costa Rica. In particular, I am studying host-parasite interactions between endangered frog populations and the fungal parasite Batrachochytrium dendrobatidis (Bd), which causes chytridiomycosis, a potentially deadly disease that threatens many amphibian communities. At least 90% of the 34 species of robber frogs have catastrophically declined or have become completely extinct since the 1980s, likely due to this taxa’s high susceptibility to this disease. I am also quantifying how environmental stress caused by climate change affects reproduction, population dynamics, and susceptibility to chytridiomycosis in remnant populations of critically endangered robber frogs.


The critically endangered Golfito robber frog (Craugastor taurus) in Punta Banco, Golfito.

In the last decade, some populations of the Golfito robber frog have been rediscovered in the peripheral areas of their historic home range. This suggests that 1) peripheral populations may have survived environmental threats that affected core populations, 2) the slow recovery has made these declined species almost undetectable across their range, and 3) there might be more cases of remnant populations that still thrive but remain undetected. Remarkably, rediscovered remnant robber frog populations coexist with B. dendrobatidis without experiencing chytridiomycosis and the proposed project aims to identify the mechanisms that allow these susceptible frog species to coexist with this lethal parasite.

With the help of volunteer field assistants, I am conducting habitat monitoring and parasite detection to evaluate the risk of extinction of remnant populations three times every dry season. Specifically, I am sampling fast-flowing stream networks in Punta Banco, which are the only known streams that sustain stable populations of the Golfito robber frog. I am also monitoring and continuously looking for the Golfito robber frog in streams in the localities of Uvita, Golfito, and Rincon de Osa (this latter location historical represents the most abundant populations of the Golfito robber frog before its decline during the 1980s and 1990s).

In every stream, we are conducting multiple linear transects. On every trip to the field, we characterize every transect by measuring several environmental variables such as air temperature, humidity, stream width and depth, and canopy cover, among others. We catch individuals of all occurring frog species and measure the snout-vent-length and body mass. We also swab the frog’s skin to collect Bd zoospores. Moreover, we analyze water samples to determine if the concentration of Bd zoospores varies across stream location.

Stream monitoring in Rincon de Osa


Stream monitoring in Uvita.


Filtering of water samples from Quebrada Agua Buena in Rincon de Osa, with the aim of detecting Bd zoospores.

I am combining my research with education and outreach activities in order to share our findings with the public and policy-makers, with the goal to create optimal conservation policies for these species. In the long term, I aim to:

  1. Propose and implement in-situ strategies to increase the survival of adult frogs and recruitment of juveniles in remnant populations.
  2. Expand the range of declined robber frogs across their original home range.
  3. Establish a long-term monitoring project in collaboration with volunteer local groups, students, and professionals.

Invited speaker at Universidad de Costa Rica, recinto de Paraiso in June, 2018. Here I presented this project to ecotourism students.



Teaching Mangrove Awareness in Térraba-Sierpe

Blog Post by Monica Espinoza, Marine Conservation Scientist

The Térraba-Sierpe Wetland presents the most productive and biodiverse mangrove ecosystem in the South Pacific of Costa Rica. However, not everyone knows the importance of this habitat in our day to day life. For this reason, we decided to celebrate World Mangrove Day with the School of Ajuntaderas, Sierpe.

Our special guests were the children of this community who learned about the importance of mangroves, fire prevention and waste management. It is important to recognize that boys and girls are carriers of information. They must be listened to and can transmit these messages to the people around them. In this way, people will be aware of the importance of the natural environment in which they live and generate a culture of protection of the wetland.

During the activities, Osa Conservation’s team taught that mangroves are tree species capable of growing and tolerating high salt concentrations in intertidal waters. In addition, they have a root system that offers a sanctuary to small fish and protect the coast from strong weather events.

Our partner ACOSA presented a captivating story to the children about the prevention of forest fires. And to the surprise of all the students, the protagonist of the story Toño Pizote (the mascot symbol of environmental conservation) made an appearance, which brought joy and excitement to everyone.

The Municipality of the Osa collaborated with a dynamic to learn to differentiate the various types of waste and management strategies in order to combat the large amounts of garbage that are produced every day (Costa Rica consumes 323 thousand tons of plastic materials per year). In addition, we taught them how to minimize the consumption of single-use plastic products that end up on beaches and in oceans (80% of marine pollution is plastic) by using reusable bottles and cloth bags and rejecting straws.

Education is an essential tool to generate change towards the conservation of marine-coastal ecosystems. This is why it is essential to get the necessary information to all those who affected, either directly or indirectly. Coastal communities are among the ones most affected by the effects of climate change, facing threats of rising sea levels rise and strong storms. Thanks to green infrastructure such as the mangrove ecosystem, these impacts are mitigated, protecting threatened communities.

It is important to continue creating these types of events for school children in order to raise awareness about the essential mangrove ecosystems and to continue protecting these habitats, not only because of their biological importance, but also because of the local community’s people who depend on them.


Plastic Prevention in Paradise

Blog Post by Noelia Hernández, Marine Programs Coordinator

When you visit Osa’s beaches of Piro and Peje Perro for the first time, it feels like a scene straight out of a movie; you can picture a shipwreck landing on one of these beautiful, untouched beaches, and the tourists becoming surrounded by nature, calm, and beauty. The trees, the mist in the background, the birds in the sky, the breaking waves, and the opportunity to see incredible species like turtles and whales all make you think that you are in a dream or in a movie. Unfortunately, a return to reality confirms that, like many other beaches, these remote paradises suffer the presence of plastics.

Plastics found on Peje Perro beach during sea turtle patrol.


A large piece of foam found on Peje Perro beach.

How is it possible that such an idyllic site has so much plastic? Yes, we already know that trash finds its way to the sea and, by currents, returns to the coast. But how have we arrived at this extreme, throwing 8 million tons of refuse into the oceans each year? To give you an idea, this amount of trash is equivalent in weight to 800 Eiffel towers. With these statistics, it is not surprising that five large trash islands have formed in the ocean. But what is surprising is the dimensions of only one of these islands in the Pacific is approximately 1.6 million km2, three time the area of France. Yes, you read that correctly: three times France! It’s hard to imagine, but you don’t have to think too much about the data to recognize the magnitude of the problem.

The amount of plastic collected in 5 hours by the sea turtle research assistants.

Thus, Osa Conservation is dedicated to keeping Osa’s beaches pristine, while finding ways to tackle the larger plastics problem. As part of a recent beach clean-up, three members of our sea turtle conservation team collected close to eight 100 liter bags of trash…in only a few hours! On separating the different types of refuse for recycling, we decided to analyze the labels and caps of the collected plastic bottles, and found that the majority of these plastics came from Asia.

Members of the marine program and Rios Saludables program separating different plastics for later recycling.


Results of analyzing the origin of the caps and labels of the found bottles. Photo: Mónica Espinoza.

Seeing all that trash in a place like Playa Piro or Peje Perro, I start to wonder if it’s true that there will be more plastics than fish in the ocean by 2050. Imagine having an ocean completely filled with trash. No thank you! The good news is that if we use all our effort, there is still time to make a change, and there are already measures that have been taken in this regard. In fact, the Osa region has been a pioneer in Costa Rica in eliminating plastic from its properties, and on the national level, all single-use plastics will be prohibited by 2021. Small daily gestures—like bringing your own bag to the supermarket, not using straws or disposable silverware, using reusable water bottles, and avoiding single use containers—will make a huge impact.

Members of the Marine Program and the Rios Saludables Program.

Will you join us in the battle against plastic? #BreakFreeFromPlastic #ForgetPlasticIsFantastic

Note: For those who are skeptical, or just curious, we invite you to read this study by Jambeck and collaborators in 2015, as well as the work done by Lebreton and collaborators that was recently published in Scientific Reports.


Silent Night Walkers

Blog by Juan Carlos Cruz Díaz, Feline Program Coordinator

It’s 5:30 am and the sun is rising above the Dry Forest of Guanacaste in northern Costa Rica. Researchers in Naranjo beach in Santa Rosa National Park in Guanacaste Conservation Area are getting ready to survey the beach. They walk along the shore looking for evidence of the presence of jaguars. Unlike in the Osa, at this beach it is common to encounter tracks left by jaguars who patrol the beach looking for prey.

Jaguar tracks along Sirena beach in Corcovado National Park.

Not many people know that sea turtles are a common prey for jaguars. Sea turtles are quite fast and agile animals in the ocean, but quite slow and clumsy on land. So when the females come to lay their eggs on shore, they are quite helpless, making them perfect prey for a jaguar.

In order to track this type of activity, researchers walk along the beach often in the mornings, documenting tracks of sea turtles who came to shore the night before. Researchers can not only tell which sea turtle species were present based on their tracks, but even more importantly, whether or not the turtle returned to the ocean. With no clear return path, it is likely the turtle was predated the night before and the researchers will then begin their search for a carcass as proof.

Sea turtle tracks in Naranjo Beach, Guanaste Conservation Area.

Guanacaste Conservation Area is one of the few places in Costa Rica where sea turtle predation by jaguars has been reported, as well as Tortuguero and Corcovado National Park. In fact, our neighbor, Corcovado National Park, was the first place where this phenomenon was reported. In the 1990s, researchers found that jaguars in the park changed their behavior, transitioning from diurnal to nocturnal during certain times of the year, which happened to coincide with the peak times for sea turtle nesting at the beaches in the area! This change suggests that sea turtles are a regular natural prey for jaguars and probably have been for thousands of years.

A camera trap picture of a jaguar with its olive sea turtle prey on Naranjo beach in Guanacaste Conservation Area.

Even though sea turtle predation is common along areas where jaguar distributions overlap with sea turtles, this natural predation does not represent a serious threat to sea turtle populations. Jaguars take about 30 turtles per year in Guanacaste and about 20 per year in Corcovado. Jaguars are also the only big cat known for this behavior, probably because they have the strongest bite among all the big cats, and crushing the turtles shell demands great strength.

It is now eight in the morning back in Guanacaste and researchers have just found a green sea turtle that was recently killed. After identifying the species, taking photographic records, and collecting shell measurements, researchers mark the shell as to not count it again in future surveys. Finally, they set up camera traps on site in hopes of identifing the jaguar that will come back to feed later that night.

Jaguar and olive ridley in Naranjo beach in Guanacaste Conservation Area (Photo credit: Alonso Sánchez).

While this specific jaguar behavior has only recently been studied, it has brought new and exciting information about variables that might explain other behaviors about jaguars, including habitat use and even tolerance of other jaguars in the same site. Such research is also helping to create awareness of the delicate balance of ecosystems and how species that may seem to be very different depend highly upon one another within the ecosystem.

Osa Conservation has collaborated with Corcovado and other national parks and partners as part of the Osa’s Camera Trap Network. Camera traps help research projects like these to collect evidence and learn more about the behaviors of Costa Rica’s wildlife and wildcats. To learn more about the Camera Trap Network and the work that Osa Conservation does to study and protect jaguars and other big cats, click here.




Never Too Old to Be a Junior Park Ranger

Blog Post by Hilary Brumberg, River Health Program Coordinator

It was a windy fall day when I joined a group of budding field researchers and nature enthusiasts to visit the Rocky Mountain National Park for the first time. As we hiked the trails, I was in constant awe of the breathtaking front-range views and the abundant wildlife, ranging from elk to butterflies to marmots to hummingbirds. But it wasn’t just the wildlife that left an impression on me.

As I was browsing the gift shop before leaving, I happened upon a Junior National Park Ranger induction ceremony that was taking place. As the middle schoolers received their badges, I could see how proud and excited they were, and imagined how happy I would have been if, at age 11, I could help protect the incredible ecosystem I had just walked through.

Flash forward, I’m at another Junior National Park Ranger induction ceremony. This time, however, the students are Costa Rican, and they are joining the Guardaparque Junior program. Modeled after the U.S. Junior National Park Ranger program, Costa Rica’s Guardaparque Juniors program teaches students to “Explore, Learn, and Protect!” national parks and reserves in Costa Rica. The program aims to form the next generation of community leaders and conservationists by educating them on the complex interactions between society and the environment. The National System of Conservation Areas (SINAC) is spearheading this pilot program with the support of local non-profits, including Osa Conservation.

Hilary teaches Guardaparque Junior students to identify macroinvertebrates, mini might-beasts whose diversity indicate river health, in the river that provides most of the water for the La Palma aqueduct system.

The first workshop for Guardaparque Juniors from La Palma High School focused on freshwater, from montane forest streams to home taps. Because freshwater conservation incorporates ecological study with social, economic and political factors, we at Osa Conservation thought it would be a good way to introduce the students to complex conversations about conservation. To illustrate how freshwater conservation affects their lives, administrators of ASADA La Palma (local aqueduct administration organization), SINAC and I took the students to the source of the stream that provides water for most of the La Palma area. I felt like a Junior Park Ranger myself as we trekked through lush old growth forest to reach where the stream fed into holding tanks and an automated chlorination system—the source of the water whenever the students turn on the taps of their kitchen sinks at home.

Guardaparque Junior students, ASADA La Palma administrators and SINAC environmental educators identify macroinvertebrates they collected from the river.


Guardaparque Junior students performed a pH test and found that the river water chemistry was neutral, which is in the healthy range.

To confirm the health of the stream, the students and I worked together to analyze the water chemistry and searched the rocks and leaf litter for macroinvertebrates, insect larvae and shrimp whose diversity indicate the health of the river. Then we followed the river downstream as it passed through cattle pasture and the bustling center of La Palma, where we repeated our mini-experiment. We found significantly lower macroinvertebrate species richness, which demonstrated how the river is adversely affected by deforestation and urbanization.

Renowned Osa botanist Reinaldo Aguilar explains that healthy forests are essential to river health because they provide nutrients, prevent erosion, regulate temperature and filters toxins.

Programs like the Guardaparques Junior and the Junior National Park Rangers are essential to nurturing the next generation of conservationists because they engage students and bring them outside. By the end of our workshop, the Guardaparque Juniors had a new perspective of how the health of the river and the health of La Palma’s residents are inextricably linked. The next time they turned on the tap, it would be with the understanding that they have a part to play in keeping their town’s water clean and preserving the health of the forest that provides it.


Mangrove Restoration Actions in the Térraba Sierpe National Wetland

Blog Post by Luis Carlos Solis, Mangrove Restoration Coordinator

The Térraba Sierpe National Wetland encompasses the largest mangrove forest in Costa Rica with an area greater than 16,000 hectares which, due to its biological importance, was declared of international importance by the International Convention on Ramsar Wetlands. In this protected area, mangrove resources have been used since pre-Columbian times when indigenous communities extracted dye from the bark of the red mangrove (Rhizophora mangle) to dye their clothing.

A section of land cleared of invasive ferns

Currently, the inhabitants of the wetland base their economy on various activities such as the extraction of the “piangua” mollusk (Anadara tuberculosa), artisanal fishing, and the isolated production of various crops and livestock; however, in the past, the local economy was based on the extraction of wood for the production of coal, firewood and construction materials, which decimated the mangrove forest. As a result of this deforestation, the “negraforra” fern (Acrostichum aureum) has dominated the wetland, which is an opportunistic species that is difficult to eradicate. Due to its high density, it acts as a barrier to the natural growth of the mangrove.

A pianguero working on planting mangroves


A pianguero in a Mangrove Nursery

As a result of this barrier in forest regeneration, Osa Conservation is carrying out mangrove restoration actions through the project “Effective strengthening of mangrove ecosystems in Costa Rica and improvement of the quality of life of the local coastal population” with funding from ALDI SÜD and KfW-DEG. Osa Conservation is pursuing this project in conjunction with the Association of Piangueros and Marine Resources of Ajuntaderas (APREMAA) in order to promote the health, integrity and sustainability of a degraded ecosystem.

The Osa Conservation Team out in the field

These restoration actions are based on active management, a technique that uses human intervention to remove the barriers that prevent the natural regeneration of the mangrove. This involves removing the fern in order create a more favorable environment for mangroves at restoration sites. The project is also establishing mangrove tree nurseries in order to accelerate the recovery processes of the ecosystem. All these tasks are carried out in conjunction by different institutions and national and international organizations such as the Osa Conservation Area, the Osa Municipality, the National University through its Applied Tropical Ecology Laboratory, Bluesensus, Shore-Rainbow Export Processing Group, ICE Group-El Diquís Hydroelectric Project, and GIZ Agency, among others.

Cutting the ferns in a restoration plot

These efforts are part of a government policy for the conservation and recovery of wetlands as a fundamental element in the sustainable development of the communities that depend on them as a way of life. For Osa Conservation, it is a privilege to be a part of these efforts and to safeguard the fundamental services the wetlands offer.

The Universidad Nacional team


The Association of Piangueros members working to plant mangroves

To find out more about our work with mangrove conservation, click here.