A botanical walk for all 5 senses

Blogpost written by Marina Garrido, Research Field Assistant

A few days ago, part of the staff and some researchers went for a walk with Osa Conservation’s botanist, Reinaldo Aguilar, from the biological station to the wildlife-friendly farm. All along the way, Reinaldo showed everyone different kinds of plants that grow in the Osa Peninsula, and shared his knowledge about the flora. We all had a lot of fun and enjoyed each plant we saw with all five senses. Since the staff is comprised of both Spanish and English speakers, we got to learn the plant names in both languages. Now, we want to share everything we learned with all of you.


We started by learning about the Bromelia, from the family Bromeliaceae. The flower blooms during the night, and signals the plant to begin growing a new branch. Once the flower has been pollinated by bats and the flower is ready to become a fruit, some of the petals are eaten by crabs. We also learned that palm trees are characteristic of the primary forest, eventhough some species, like the royal palm, can be found in different habitats.


Along the way, we met some capuchin monkeys eating the fruits of a tree called Cow tongue, or Lengua de vaca (Liconia argentia). It is not uncommon to see capuchin monkeys, spider monkeys, and white-nosed coatis snacking on the fruit of this native tree on a morning walk around the station.


Once we were inside the wildlife-friendly farm, Reinaldo introduced us to the marvelous Anacardiaceae family. Within this family, there are some of  Osa’s tastiest fruits: mangos, jocotes, pistachios, and cashews. The genus Pistacia used to have its own family, but was recently added to the Anacardiaceae family. One of the defining characteristics of this family is the resin canals visible on the pith of the plants.


We had some fun with our confusion between the Guava and Inga trees. The Guava tree is called Guayaba in Spanish (Psidium guajaba). Its leaves are opposite and simple, and the flowers are white and very smelly. Its sweet fruit is a favorite of many monkeys and the leaves possess glands that excrete oil to protect themselves from larvae. When backlit, these glands look like tiny cells surrounding the leaf. On the other hand, a species of the Inga tree is called Guaba in Spanish (Inga edulis).  Its fruit grows in a pod, which can easily be opened by hand. The seeds are found inside the pod along with the characteristic white pulp. These fruits can be found all around the peninsula and are a sweet and delicious snack for every wanderer in the Osa.

An additional tree that we all enjoyed was the Pochote tree (Bombacopsis quinata). This tree is common on the Pacific coast of Costa Rica. Its thorns cover the entire trunk and its white flowers turn red once they fall. These two unique characteristics make this tree quite easy to identify. Its leaves are edible and, according to some of our assistants, very tasty!


Celebrating Biodiversity!

Blogpost written by Eleanor Flatt, Biodiversity Research Field Assistant


In the Osa, “biodiversity” is an  understatement…

In the human world, we select people to represent our countries, our towns, our villages, our communities; it is similar in the animal kingdom. A flagship species is an ambassador for a specific habitat and normally conservation of that species or the area they inhabit has benefits for other species. Here in the Osa Peninsula, we are home to a staggering 2.5% of the planets biodiversity, living on a mere 0.00000085% of the earth’s total surface area. Now that’s impressive! This biodiversity includes many iconic, endemic, and endangered species, which are ecologically important to this region. Here are 7 of the most interesting and exciting examples you might find during your visit to the Osa.


Yellow-bellied sea snake (Pelamis platurus)

Photo by www.golfodulce.org/pelamis-en.html

Photo by www.golfodulce.org/pelamis-en.html

This beautiful yellow-bellied sea snake can be found in the temperate waters of the Golfo Dulce. Its physiological adaptations allows this species to become boat-like, with a tapered belly similar to the keel of a boat providing stability in water, along with a flattened and broadened tail, which performs like a paddle for swimming…this is the Michael Phelps of the snake world!



Yellow-Billed Cotinga (Carpodectes antoniae)

Photo by Glen Bartley

Photo by Glen Bartley

The Yellow-billed cotinga is an endangered bird whose small population occupies only a tiny area. There are estimated to be 250-999 individuals, and only 150-700 of them are mature. They occur in mangroves, lowland forest, scrub, and occasionally in isolated trees in nearby clearings. After completing a radio-tracking study to understand their habitat uses for breeding and feeding, Osa Conservation is now focusing on protecting this land through the creation of a reserve.



Mangrove Humming bird (Amazilia boucardi)

Photo by Nick Hawkins

Photo by Nick Hawkins

Mangrove hummingbirds are another vital species in the mangrove habitat. They feed mainly on the flowers of the tea mangrove and are the only birds that have adapted to collect nectar with a specialized tongue. Their diet of carbohydrate-rich sugar nectar is necessary to support the hummingbird’s significant energy demands, as their wings beat 200 times per second. They will feed on between 1,000 and 2,000 flowers each day, allowing the tea-mangrove flowers to maintain high pollination rates. We are in the midst of starting a new project to protect the mangrove habitats here in the Osa.



The White Lipped Peccaries (Tayassu pecari)


Populations of White-lipped peccaries are decreasing due to hunting and habitat degradation and fragmentation. Consequently, this species is now listed as vulnerable. Records indicate that they can form groups of as few as 5 to as many as 200 individuals. In conjunction with the wildcat program, Osa Conservation will be radio-collaring and  monitoring the  peccary population, as they are essential prey for large cat populations.



Green Turtle (Chelonia mydas)

Manuel Sanchez

Photo by Manuel Sanchez

Green turtles, listed as endangered by the ICUN, are one of the many sea turtle species that come to nest here. It is hypothesised that the hatchlings leave the nesting beach and begin an oceanic phase by floating passively in major current systems, which serve as developmental grounds, after several years. They then proceed to seagrass and algae-rich areas where they forage until maturity. In the Osa, we have the Golfo Dulce, which is rich in these foods, and we monitor Playa Peje Perro, which is considered an important beach because  of its high population of nesting female green sea turtles.



The Spider Monkey (Ateles geoffroyi)

Photo by Manuel Sanchez

Photo by Manuel Sanchez

Spider monkeys are energetic and agile movers found high in the canopy. Recorded as endangered on the IUCN Red list due to hunting, pet trafficking and habitat fragmentation, spider monkeys are in dire need of protection. Osa Conservation works hard to protect their areas of habitat, including important corridor routes surrounding national parks, and restore other aspects of their habitat. Spider monkeys are typically found in groups of 20-30 individuals, but often split up during the day to forage. In the evening, they all return to a specific “sleeping tree” to be together as a big family.



Golfo Dulce Poison Dart Frog (Phyllobates vittatus)

Photo by Manuel Sanchez

Photo by Manuel Sanchez

The Golfo Dulce poison dart frog is yet another species affected by habitat fragmentation and degradation, both of which have caused it to become endangered. As an endemic species here in the Osa (meaning it is only found in this region), this species is all the more special! Females deposit eggs on leaves above the ground, then the males carry the hatched larvae to small pools where they complete their development – a true team effort.


These are just a few of the many wonderful and magnificent species you can find here in the Osa Peninsula that we are working to conserve by protecting and restoring their habitats.  These are just a few of the amazing species we can appreciate as we celebrate World Biodiversity Day!










Celebrating Endangered Species Day! Endemic and Endangered: Stories of a frog and a tanager.

Blogpost written by Alejandra Rojas, Naturalist Guide and Avian Program Coordinator


     black-cheeked-ant-tanager-_low-qualityPhoto 1:  The endemic & endangered Golfodulcean Poison-arrow Frog  and Black-cheeked Ant Tanager (Photo credit: Manuel Sanchez Mendoza)


What does a Golfodulcean Poison-arrow Frog and a Black-cheeked Ant-tanager have in common?

Not only are they endemic to the Osa Peninsula in Costa Rica, but they are also endangered – a term used to describe when there are so few individuals surviving that the species is at risk of no longer existing in the wild.  There are many reasons that could drive a species to this status, including: habitat loss, illegal pet trade, introduction of exotic species, diseases, illegal hunting or overfishing.


Why does the Osa have so many endemic species?

Because of its geological formation where it evolved as an island before merging with the Costa Rica mainland (nearly 2 million years ago), the Osa Peninsula harbors a high level of endemic species. Endemic species are those which are found exclusively in one location in the world. This endemism, together with the immense concentration of life forms found in this region, is the reason why the Osa is globally known as a biodiversity hotspot and has such an important conservation value.


Why are these endemic species endangered?

Although the Golfodulcean Poison-arrow Frog and the Black-cheeked Ant-tanager can be found in areas close to the Osa Peninsula, populations are isolated, and in the case of the frogs, are considered a rarity. According to the IUCN Red List of Threatened Species (2017) both species are endangered because of their small distribution range, confined to protected areas, where logging and continuously habitat loss around these areas  are the major threats to both species nowadays. In the case of the frog, water pollution due to gold mining in the Osa is also a huge threat.


What is it like to experience these endemic & endangered species?

If you have never had the chance to explore nature in the Osa and see these animals, I invite you to go on an imaginary hike: It´s 5:15 am and we embrace an early morning hike into the rainforest. Binoculars in hand, a nice flute-like sound indulge our senses: it is the Black-cheeked Ant-tanager, but we have not seen it yet. This bird performs this particular song only in the early morning, sometimes accompanied by the howler monkeys´ chorus.

Time passes and a chatter-like sound captures our attention. Should we look up to the canopy? No, we better focus in the understory, where this species inhabit. As all tanagers, the Black-cheeked Ant-tanager fly in family groups and forage in the lower levels of the forest in search of small arthropods and fruits- a behavior that makes them important for controlling defoliating arthropods and also for dispersing seeds. Wait! Be careful with these bunch of army ants passing through the trail; let´s find a good place to enjoy the show:  the Black-cheeked Ant-tanagers are following the “ant swarm” with a mixed flock. We watch for 10 minutes until they disappear in the vegetation, following the path of the ants.

Photo 2: Black-cheeked Ant Tanager (Photo credit: Manuel Sanchez Mendoza)

As we keep walking in the rainforest another sound captures our attention:  the Golfodulcean Poison-arrow frog-  a diurnal species (active both day and night).  We can hear two calls but they are far away; maybe if we move towards a creek we can find them. Indeed, as we approach a small creek, we spot two males calling together on top of a log! These frogs are very territorial and we are witnessing a territorial display. Their colors (known in biology as aposematic coloration) are warning us that they are highly toxic. Continuing our walk along the creek, we find another male, but this time carrying tiny larvae on his back. He will soon deposit them in the water for their next life stage. Our hike concludes and we are thrilled to have successfully found these two endangered species that can only be seen in the Osa.

Photo 3:  The endemic & endangered Golfodulcean Poison-arrow Frog (Photo credit: Manuel Sanchez Mendoz

Why are endangered species important?

Experiencing nature is one way we can understand the importance of protecting endangered species. Each species, endangered or not, has a role to play in the greater ecosystem, whether by dispersing seeds, controlling other species, or by directly helping other species maintain the ecosystem health. These two endemic species- the Golfodulcean Poison-arrow Frog and the Black-cheeked Ant-tanager- are also important because they act as umbrella species. This means that if we protect their habitat we are also protecting the habitat of other important species, including other endangered animals and plants as the Jaguar (Panthera onca), the Scarlet macaw (Ara macao) and the Nazareno or Purpleheart (Peltogyne purpurea) found in the Osa.

Is it too late? Not yet!

Do we still have time to save the Golfodulcean Poison-arrow Frog and the Black-cheeked Ant-tanager? Yes, but we need ongoing efforts to conserve the vital ecosystems that support these animals and the surrounding biodiversity. Because these species are restricted to protected areas and they know no political boundaries, it is even more important to prioritize the buffer areas, forest patches and biological corridors that connect their habitat and are the last stronghold for their survival.

Please help Osa Conservation continue to save these amazing species and so much more! 100% of your donations goes toward helping conserve the habitats and ecosystems on which these species and so many more rely! You can visit our page here to make a donation or visit here to learn about visiting the Osa and seeing these incredible creatures for yourself! Every effort counts!


Celebrating Migratory Birds! Migratory birds, wetlands and people in the Osa Peninsula

Blogpost written by Alejandra Rojas, Naturalist Guide and Avian Program Coordinator

Every year, thousands of birds around the world start a long journey that is fundamental to their survival: migration. Each species has its particularity: they fly in flocks or by their own, during the day or the night, they rest or they fly restless, large distances or short distances. Despite their different migration strategies, all of these birds have something in common: they face challenges to survive their “flyway” – a term used to describe the route regularly used by large numbers of migrating birds.

One of the biggest threats to many migratory birds is habitat loss along the flyway due to fragmentation, pollution and human development. Wetlands, in particular, are especially fragile and important areas for a high diversity of migratory birds. Unfortunately, wetlands are also among the most endangered ecosystems worldwide, largely due to loss of forest coverage.



Wetlands, such as mangroves, are one of the most productive ecosystems in the world. They provide key ecosystem services such as water storage, nutrients production, protection against storms, stabilization of coastal areas, purification of water and retention of sediments. Humans also obtain other benefits directly from wetlands, such as fishing, aquaculture and tourism opportunities that provide an economic income for local communities.

Indeed, there is a special connection between birds and mangroves! Because of  their sensitivity to environmental changes and the impacts on their flyway habitats, migratory birds are important biological indicators that help us understand the ecological health of an area and can help inform conservation planning.

The Osa Peninsula has large extensions of mangroves, riparian forests and estuarine lagoons that act as a temporary home for aquatic birds that visit Costa Rica during their migration and stop sites. Ducks (Anatidae), herons and egrets (Ardeidae), plovers and sandpipers (Scolopacidae and Charadriidae), terns and gulls (Lariidae) and warblers (Parulidae) are between the most commonly seen migrants in the mangroves.



Conservation efforts like those of Osa Conservation, which include the restoration of wetlands, help ensure the sustainable restoration of migratory bird habitat on which so many species rely. Through education and local awareness efforts, Osa Conservation encourages the involvement of local communities to help mitigate the negative impacts of human activities and to share the message of the importance of migratory birds and their habitat.  Conserving wetlands for migratory birds is crucial for their survival and ours: Their Future is our Future.





Volunteering with Rios Saludables

Blogpost written by Alexander Cotnoir, Volunteer with Rios Saludables Program


Hello everybody! My name is Alexander Cotnoir, and before I share a snapshot of my work at Osa Conservation thus far along with some of the most exciting experiences I’ve had working with the Ríos Saludables Program, I’d like to introduce myself and share why I decided to join the Ríos Saludables Program as a volunteer over the course of the next few months.




I am currently a sophomore at Dartmouth College in New Hampshire, pursuing a degree in biology and environmental studies. Despite my current academic pursuits, my passion for ecology and sustainable agricultural/development practices started long before my entrance into higher education. During my childhood, I enjoyed fishing, hunting, swimming, and exploring the great outdoors along the Quebec border in northern Vermont, and later working for a local branch of the U.S.D.A. and birdwatching with my sister. My passion for the intersection between land use practices, native/local cultures, and conservation was fostered through summer jobs (as a Nutrient Management Plan Intern for the U.S.D.A.’s Natural Resources Conservation District), where I worked with farmers to minimize nutrient loading from dairy farms into local watersheds. I have also fostered an interest for conservation and land-use through conversations with my grandfather, who is a Tribal Leader of the Coosuk Band of the Abenaki Nation working to manage our tribal lands in northern Vermont. At Dartmouth, my interests expanded with courses ranging from “Writing Natural History,” to “Climate Change and Agriculture” and “Native Peoples and Environmental Change” which have allowed me to explore the socio-cultural and economic aspects of environmental problems.



(Heading to our first sampling site at a cattle ranch near Puerto Jiménez)


As I was searching for an off-term opportunity to gain field experience in biology and environmental science, the Ríos Saludables Program appeared to be the perfect opportunity. Given my previous experiences with macro-invertebrate sampling and hydrological systems, I knew the Ríos Saludables Program would be an ideal opportunity to continue exploring watershed science, as well as to gain new insights into community-oriented conservation initiatives in a foreign country. Aside from my interests in gaining field experience, becoming involved in a community-oriented conservation program, and applying my studies in biology and environmental science, I also saw volunteering with Ríos as an amazing opportunity to practice my beginning-level Spanish, and to explore the amazing flora and fauna that call Osa’s rainforests home.


(Working at the Osa Verde organic farm to plant native rainforest tree seedlings. These seedlings will be utilized in a number of reforestation plots on former cattle ranching lands)

Although I’ve only been living at Osa Conservation’s biological station for three weeks, I have already observed that the Osa Peninsula rightly deserves National Geographic’s description as the “most biologically intense place on earth.” Within my first week and a half, I spotted scarlet macaws, toucans, black-throated trogans, green and Olive Ridley sea turtles, a false coral snake, four species of monkeys, peccaries, a tamandua, and even a puma that decided to walk down one of the forest trails in front of me (I was told that this is a rare sight that many locals often don’t see in their lifetimes!). Aside from feeling an immediate sense of awe at the plethora of flora and fauna that inhabit the vibrant forests around the biological station, I’ve also found the local community’s excitement about their unique natural landscape very refreshing and conducive for fostering discussions about plants, animals, and conservation initiatives alike. Despite the many mistakes I make using my Spanish, I have never felt embarrassed because the people are all so kind and appreciate the attempts of Spanish beginners.



(Explaining nitrate test procedures to Alex, a local farm co-op employee, at the spring which supplies drinking water to his hometown)



Thus far, one of the most exciting experiences working for the Ríos Saludables Program was a trip Rachael and I recently took to sample near a springhead feeding water to a community in Venegaz. Aside from the breathtaking beauty of the Costa Rican countryside, with its winding red-dirt roads carving their way through farmsteads and massive ajo trees, I had a great time sampling macroinvertebrates with Rachael and a local community member who joined us at the stream. Almost immediately after we arrived at the sight, I spotted a green and black poison dart frog hopping in the leaves beside the brook, which the gentlemen excitedly identified for us and shared some of his expertise on the animal. The entire time we spent sampling the stream was enjoyable due to the gentleman’s enthusiasm, my attempts to explain nitrate tests in Spanish, and the tangible connection between watershed and community health that was evident as we sampled near the springhead water collection tank.

Over the course of the next two months, I hope to help standardize Ríos Saludables protocols so that the sampling data can be applied to a larger academic context. I also look forward to doing community outreach with students and local community members, and finding ways to better assess the impact of agricultural activities and road crossings near Puerto Jiménez. I am also excited to help establish watershed testing locations along several additional rivers in the area.

Hasta luego,


Interested in volunteering with Osa Conservation? Learn more here about our various volunteer opportunities!

Data Entry Services India