Hand-collected seedlings in Osa Conservation's tree nursery

By Max Villalobos

The arrival of May brings heavy rain to invade the forests of the Osa Peninsula. It is a time of great change and exceptional beauty. Millions of tiny trees and leaf litter form a living carpet across the colorful forests. These seemingly insignificant small seedlings are invaluable because they represent the renewal of a healthy ecosystem and over time, they will slowly become the forest of tomorrow.

Native tree saplings ready to plant in Osa Conservation's restoration plots

Rainy season has meant a lot of activity at Cerro Osa because it is the time for one of the most rewarding tasks of our work in conservation and land management, tree planting. This year we will plant 8,000 trees of 50 different native species in our forest restoration plots. These new trees will begin the process of ecological succession that will allow us, after several decades, to recover biodiversity in these degraded areas and get a forest that serves as habitat to such important species as the Spider Monkey, the Puma, the Peccary and hundreds of birds.

So I invite all those who are interested to have fun restoring the Osa rainforest with us as volunteers in our forest restoration programs.

Contact reservations@osaconservation.org

Our executive director Manuel Ramirez and conservationist Theo Gund planting a tree in our forest restoration plot.

Our new Land Conservation Manager, Max Villalobos

Our new Stations Manager, Larry Villalobos

As with any well-oiled machine, Osa Conservation is nothing without its nuts and bolts. Our wonderful staff dedicate a tremendous amount of time and energy to helping us protect the land and wildlife of the Osa Peninsula, and today we would like to introduce our newest team members: Larry and Max Villalobos.

Born and raised in Costa Rica, Max and Larry have always been avid fans of nature. Prior to his position at Osa Conservation, Larry, a self-employed water-rappelling entrepreneur,  had been accustomed to moving around due to his work in hotels. Both Larry and Max feel a close emotional bond with the Osa Peninsula, having always known it’s significance to Costa Rica and to the world.

“The Osa peninsula has always been an icon of biodiversity in Costa Rica,” Says Max, our new Land Conservation Manager. “Personally, I think it’s one of the most impressionable places I’ve ever known.”

As Station Manager, Larry has worked closely with the rest of our staff  to start improvements around the Piro Biological Center such as drafting new maps, building new signs and stabilizing the Cerro Osa trail. Max, on the other hand, has been overseeing Osa Conservation’s land conservation program which includes our native tree nursery and forest restoration efforts.

“I really like the Osa Peninsula and being able to work surrounded by nature and wildlife is amazing for me,” says Larry. “Working in a place like this where I can help conserve the nature of Costa Rica makes me feel like a better person!”

Please join us in giving a warm welcome to Larry and Max, as we look forward to an extraordinary future with them on our team!

Top: The vibrant yellow coloring of the X sea snakes in the upper latitudes of Golfo Dulce. Bottom: the typical black/yellow coloring displayed by YB sea snakes seen near the mouth of the gulf.

A few years back, an Osa friend told me that entirely yellow sea snakes could sometimes be found in Golfo Dulce. The serpents were said to be as bright as canaries. The only sea snake found on the Pacific side of Costa Rica is the pelagic sea snake (Pelamis platurus), commonly named “Yellow-bellied Sea Snake,” because it’s black on the back and yellow underneath with black bands or spots on the tail. I finally found some scientific publications reporting rare accounts of all-yellow sea snakes along Central America — including Golfo Dulce — sprinkled in with the bi-colored snakes. Intrigued, I decided to make the pelagic sea snake one of our focus animals for the 2010 survey.

To characterize the two color varieties in my field notebook, I labeled sightings for the typical black and yellow striped specimens as YB (for Yellow-bellied) and all-yellow or predominantly yellow specimens as X (for xanthic, which means “having yellow color”). We expected to find the X snakes scattered throughout the gulf among the YB snakes, but we were in for a big surprise.

All of our YB sea snakes were documented down near the mouth of the gulf and our distribution data showed the upper half of Golfo Dulce to be populated exclusively by X sea snakes. Moreover, our GPS sighting points marked a gap of over 13 miles between the two groups. We were stunned! We had pinpointed a resident xanthic colony separated from the broader Pacific population! Despite being the most widely ranging snake in the world, a xanthic colony of Pelamis has never been documented anywhere else, so the finding was indescribably exciting! By the end of our research we had logged a total of 68 X sea snakes near the inner basin of Golfo Dulce.

For anyone interested in the full scientific data relating to our research of these snakes, a paper entitled “Geospatial and Behavioral Observations of a Unique Xanthic Colony of Pelagic Sea Snakes, Pelamis platurus, Residing in Golfo Dulce, Costa Rica” is available through the journal Herpetological Review (March 2012).

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.

Side by side, you can begin to see the characteristics that visibly differentiate the three sea turtle species we documented inside Golfo Dulce.

When we began our research, nobody expected us to find very many sea turtles inside Golfo Dulce — most sea turtle activity was thought to occur on the Pacific side of the Osa Peninsula. It turned out that chelonids were the most frequently seen family of animals, accounting for 38 percent of our total sightings. Discovering such significant numbers of sea turtles was one of our most important findings. Sadly, fishermen with many years of experience in Golfo Dulce say the sea turtles there have declined at least 30 percent in recent years.

Jorge and I documented three species: Pacific Black sea turtles, still commonly referred to as “Greens” (Chelonia mydas agassizii), Olive Ridley sea turtles (Lepidochelys olivacea) and Hawksbill sea turtles (Eretmochelys imbricata). Locals also reported seeing near-extinct Pacific Leatherback sea turtles (Dermochelys coriacea) inside Golfo Dulce. That’s four endangered species of sea turtles utilizing the embayment. Amazing!

Our biseasonal data show Golfo Dulce to be a year-round feeding and breeding area for endangered Green sea turtles. We logged over a hundred sightings of them between both surveys. This species, by far the most common, was usually observed in the upper regions of the gulf resting at the sea surface. But we also documented Green sea turtles mating in all four quadrants of the inlet, so their use of the fiord waters appears widespread.

Although some amount of nesting may occur throughout the year, the primary nesting period for Olive Ridley sea turtles in Costa Rica is from July to December — the rainy season. Although we did see a couple Olive Ridleys in January/February, we weren’t surprised that the numbers and frequency of sightings rose dramatically in July/August. During the rainy season survey, nineteen Olive Ridley sea turtles were documented, including a pair mating just off-shore from Puerto Jiménez. Every lora, as the Olive Ridley is called in Spanish, was observed in the lower half of the gulf, suggesting that is the primary sector for them

Between 2010 and 2011, we saw only ten Hawksbill sea turtles. They were found in various locations around the gulf, although all close to the shoreline. The small population of Hawksbills in Golfo Dulce is particularly important because this species is critically endangered. In fact, until recently Hawksbills were considered functionally extinct in the eastern Pacific! Called carey in Spanish, this species is often locally described as “the little turtle”, something that was confusing to me at first, since the Olive Ridley is published as the smallest species inhabiting Costa Rican waters. But of course the locals were right. The Hawksbills seen during our surveys were unquestionably the tiniest.

Since sea turtles nest along the shores of Golfo Dulce, people who find their tracks are often curious which species left them. While Olive Ridleys and Hawksbills crawl one front flipper over the other, leaving an asymmetrical track in the sand, Greens pull with both flippers—like dual canoe oars—creating a more balanced print. The size of the tracks can also help determine the species.

Anyone with interest in learning more about sea turtles or working with them on the Osa Peninsula should check out the Osa Conservation’s Sea Turtle Conservation Program.

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.

Dolphin B43 shown alongside a rendered outline of its dorsal fin. We saw this individual five times.

An unexpected but delightful result of our survey work in Golfo Dulce was the identification of about 80 individual Bottlenose dolphins (Turciops truncatus), some of which can be seen in the Appendix of my 2010 report.

How does one go about identifying dolphins? Well, pioneering biologists studying various species discovered ingenious ways to distinguish individuals. Jaguars have unique spots. Gorillas have unique nose prints. Dolphins have unique dorsal fins. By examining the shape, natural markings, scars and trailing edge, a dorsal may appear as distinct as a fingerprint. Of course dolphins don’t sit quietly at the surface while you study the intricacies of their dorsal patterns, so ID work is best done through photos. Luckily, we managed to get photographs for almost 90 percent of our dolphin sightings.

A good close-up photo allows us to visualize, even trace, the dorsal outline. Once we “know” a dolphin, we can often recognize it from a distance. Then we can go back and look for it in other sighting photos and thus begin tracking its movements, as well as associations with fellow dolphins. It’s a tedious task, yet also exciting. Suddenly a sea of dorsal fins becomes an intriguing puzzle of “who’s who”.

Photo-ID catalogs and databases are created to expand scientific understanding of dolphin populations and their habitats. But good science is only part of it. I also hope our photo-ID images will serve as outreach material. Familiarity breeds a sense of responsibility — we are more likely to help those we know — so by introducing the Osa community to their dolphin neighbors, people may be even more inspired to protect them.

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.

They have a saying in Costa Rica: “Pura vida.”

It literally translates as “pure life,” but to Costa Ricans, it can be inserted into many contexts and applications: “Thank you,” “You’re welcome,” “So it goes,” “Wonderful.” It is used so freely here I wouldn’t be surprised if it meant, “Pass the papaya, por favor.”

I’d dreamed of visiting Costa Rica since I was 12, and recently for two glorious weeks I got to sample the “pure life” – visiting the southernmost quarter of this West Virginia-sized nation – from San Jose down nearly to Panama.

My introduction to the Pacific rain forest lowlands began with Roy Orozco, a soft-spoken, gracious naturalist out of Quepos. First light for birding in the tropics is 5:30 a.m., so Roy picked me up at 4 a.m. at the Costa Verde II parking lot near Quepos to drive an hour and a half up the coast to Carara National Park, west of San Jose.

Carara, one of Costa Rica’s marquee ecotourism destinations, is a unique mix of “life zones,” where the drier habitat of the north meets the wet lowlands of the south.

A day in the field with Roy – a whirlwind of activity from pre-dawn to post-sunset – netted us 110 bird species, lounging crocodiles, great conversation, much learning, and casados for lunch – Costa Rican “comfort” meals typically composed of salad, beans, rice, potatoes, fried plantains and a meat side.

The special of the day was pollo sudado – “sweaty chicken,” traditionally enjoyed with a cold beer and a splash of Lizano salsa – the national condiment of choice.

The heady blend of Costa Rican highlights rendered me emotionally and intellectually lightheaded. We decided to do it again the next day.

At 4 a.m. the next morning, we barreled – a generously mild description of Costa Rican driving style – up the highway to San Isidro and beyond, rising 8,500 feet into the cloud forest at Mirador de Quetzales, a rustic Costa Rican-run resort where the quetzal is king.

If you don’t know about the resplendent quetzal, you haven’t been paying attention in life. The male quetzal is a 2-foot-long (more than half of which is tail) beauty decked in iridescent red and green. The female, even without the tail, could star in her own TV series.

The quetzal is the Holy Grail bird. Nature lovers everywhere seek it, and when they do, they pilgrimage to Costa Rica.

So here too was I. It was 41 degrees in the dawn, and because of poor planning, I was wearing sandals. But the adrenaline rush of seeing birds such as the fiery-throated hummingbird, the flame-colored tanager and the flame-throated warbler kept me warm.

We located six quetzals feeding in the fruiting moss-draped avocado trees, plus a dizzying assortment of other high-altitude wonders such as the yellow-thighed finch, long-tailed silky-flycatcher, slaty flowerpiercer and wrenthrush.

From there we traveled down a long valley to Savegre Mountain Lodge, where a leisurely mountain hike provided birding highlights such as the black-faced solitaire, the sulphur-winged parakeet and spangle-cheeked tanagers – eight in one tree.

A quick stop before dark descended like a velvet curtain at 5:30 p.m. rewarded us with the green-crowned brilliant hummingbird, silver-throated tanager and a total of 70 bird species for the day – a full half of which I had never seen before.

Back in my room the phone rang. It was Roy calling to joke that “he missed me already.” I thanked him again for the thrill ride. It had been a fantastic two days exploring southwestern Costa Rica, but the biggest part of my adventure was yet to come.

The next day I returned to San Jose to meet up with a contingent heading down the Pacific Coast to the Osa Peninsula.

The tour was led by Craig Thompson, a Wisconsin Department of Natural Resources West Central District land program manager based in La Crosse, in conjunction with Osa Conservation, a Costa Rican nongovernmental, nonprofit conservation organization.

The rest of the group consisted of Mary, Craig’s wife; Carole Schneider-Phillips of La Crosse; Sarah Hole and Eileen Mershart of Madison; Mary Jo and Tom Clark of Melrose; and Rory Cameron of Chippewa Falls. Rory and I had decided to team up with the tour back in June.

After an hourlong flight, we deplaned at the jungle airstrip in Puerto Jimenez. For the next six and a half days, it would be just us and the rain forest, but the rain forest has got a lot of personality.

Five percent of the world’s bird diversity – more than 800 species – lives in Costa Rica, half of them in the Osa Peninsula. Fifty-five of those bird species breed in Wisconsin and winter in the Osa Peninsula – the “Wisconsin-Costa Rican connection” that is at the root of the tour’s origins. (Among those birds are the Tennessee warbler, golden-winged warbler and Baltimore oriole.)

The Bell Family Foundation, a private charitable foundation, donates annually to the DNR’s Bureau of Endangered Resources. Of that, $25,000 is passed on to Osa Conservation to help preserve rain forest habitat. A $500 portion of the trip cost each of us had paid also went directly to the cause.

“You try to protect as much forest as possible,” Thompson said. “There is a real urgency associated with this kind of work.

“This is such a beautiful place that a lot of people from Europe, Canada and the United States are coming down and building second homes, and as a result, land prices are skyrocketing.”

In the 1970s Costa Rica experienced one of the highest deforestation rates in the world. By the ’80s, national parks like Carara and Corcovado, in the Osa Peninsula, were being created.

Costa Rica faces a bit of an irony. The beautiful parks that support the country’s No. 1 “product” – ecotourism – are still threatened.

Gold miners that work the parks poach freely, sometimes bragging of killing off hundreds of wild peccaries, or pigs.

There is talk of building an international airport in the mangrove forest where the endangered yellow-billed cotinga lives.

But the real indicator of habitat health lies not in bird populations, but with cats. As the jaguar goes, so go the birds.

“The jaguar is the umbrella species, so if you protect enough for them, everything else falls in place. Their primary prey is peccaries so you need the big forest to keep everything stitched together,” Thompson said.

Even the grand idea of pristine forested parks isn’t enough. “Islands” of good habitat do not ensure viable gene pools.

“What we want to do is create a corridor that extends from the tip of the peninsula all the way up to Corcovado’s southern boundary,” Thompson said. “You’ve got a swath of protected lands that extend from Corcovado, so you’re not going to get isolated patches of forest that result in isolated populations and the host of problems associated with that.”

Studies have shown birds forced into subprime habitat arrive later and have smaller clutches of eggs, while birds that come from healthy habitat are more successful breeders.

“If tropical forests cease to exist, the birds are gone. It’s really very basic,” Thompson said.

So, why not invest in Costa Rica?

“(U.S. citizens are) currently sending $180,000 a year to Canada to support wetlands conservation – supported mainly by waterfowl stamps. This is a chance for birders to step up to the plate. It’s a really big deal.”

Our bird guide for the week, Nito Castro, was one of sharpest naturalists I’ve ever met. Not only was he a step ahead of me on all the birds, but he could line them up in the scope before most of us could get them in our binoculars.

He did it all on a gallon of gallo pinto a day – a Costa Rican staple consisting of black beans and rice – well … maybe two gallons.

The “jungla” isn’t for everyone, and I think that is a good thing. This is not a place for the tiny hawk of heart. Paltry tyrannulets need not apply.

You are going to tramp for miles in clunky knee-high boots meant to guard your shins from venomous snakes and you are going to sweat.

You also will pass beneath “cicada showers.” So many of the insects are feeding in the treetops that their bodily waste sometimes falls down like rain from the canopy.

And the spiders here eat small birds.

But I survived each day supremely, thank you. My only complaint was a serious case of “binocular shoulder” from watching all the birds high in the trees.

From the veranda at supper, we admired the coastline tailing off to the northwest. Bunking down for the evening, we were lulled to sleep by the sound of the surf broken by the tremulous wails of great tinamous and the purring of crested owls.

Once again we rose before light for a bite to eat before hiking. Nito pointed out not just the slaty-tailed trogons and the charming hummingbirds, but also tent-making bats; ajo – or “garlic trees”; and a parrot snake.

The group paused faithfully at every scarlet macaw crossing. The bright red, gold and blue birds – more populous here than anywhere else on Earth – are always paired. With their long tails, they appeared to be 4 feet long in the air.

After all the hiking I was one “sweaty chicken.” It was time for a rinse.

But in the Osa Peninsula, they run a tight green ship. They conserve everything – especially hot water. I must confess I emitted an unmanly whimper the first time I ducked under the shower head – shifting from 88 degrees to 40 in one pass. Now that’s invigorating. It felt good to be clean again, however, and I no longer smelled like an ajo.

After two nights at Cerro Osa, we hiked to to Piro Research Station, where we would spend the next three nights catching whatever sleep we could between the raucous barking of howler monkeys.

From there, Playa Piro – the longest stretch of undeveloped beach in Central America – was an easy stroll. We got a monkey “grand slam” along the way, seeing all four of Costa Rica’s primate species: spider, squirrel, white-faced capuchin (aka Taco John ads) and the incredible howler.

The mantled howler monkey is widely considered to be the loudest land animal on the planet. (Funny … I thought the title belonged to us humans).

My first encounter with them – in the deadest, darkest middle of the night – was one of those “What the hell was that?” moments. Like everyone else, I quickly became enamored of the wild and spectacular sound.

I topped every day of hiking off with a cold Imperial, the cerveza (beer) of choice in Costa Rica, and great food, whether I was ready to eat or not. In fact, upon returning to the States, I was briefly rendered confounded and helpless when no one volunteered to step forward and slide a heaping plate of food in front of me.

Dinner at Piro is by candlelight in the high-ceilinged open veranda, with pauraques – the common Costa Rican nightjar – strafing the airspace between the supper table and the high thatched roof in pursuit of bugs.

After supper one night fellow traveler Sarah Hole had an announcement to make:

“The bathroom around the corner is temporarily closed; the army ants are cleaning it.”

That, of course, brought Nito and me at a run. The entire floor of the tiled bathroom, and halfway up the walls, was crisscrossed with lines of ants. Nito, flashlight in hand, pointed out the vanquished black ants, crickets and spiders being carried back to the invaders’ bivouacked nest, while a tiny cockroach dashed madly through the lines, escaping with its life.

For the last two days of the tour, we said goodbye to Nito and loaded into taxis for the bumpy ride to the Golfo Dulce region and Bosque del Rio Tigre Lodge near Dos Brazos.

“BRT,” as it is called for short, is a lovely, compact, two-storied resort operated by Liz Jones and Abraham Gallo. Abraham and his nephew, Ulysses, serve as expert bird guides.

Short forays into the wild got us up close and personal with a dozen species of hummingbirds and a shy uniform crake.

Lounging in hammocks, we were treated to a “mixed flock” of birds including bay-headed Tanagers, endangered black-cheeked ant-tanagers, a squirrel cuckoo and red-legged honeycreepers.

Little tinamous, blue ground-doves, and gray-necked wood-rails congregated at the feeding station to peck at rice before it was carted off by leafcutter ants.

When we did the “bird roundup” at days’ end, we were delighted to tally 141 species.

Each night, unfailingly, I lay in bed, with bats passing in and out the open windows, thinking, “I’m sleeping in the jungle” and wondering what was going on in the “outside world.”

But the “outside world” is here inside the rain forest.

What we call jungle is really life turned on high – a rain forest buzzing with diversity and drenched in cicada pee and filled with 1,500 kinds of trees – that is more raw and more real than anything you ever will see on television or read about in a newspaper. Nothing on earth substitutes for deep immersion.

Pura vida.

Steve Betchkal is a freelance writer for the Leader-Telegram based in Eau Claire, WI.

Diseases aren’t supposed to be the first thing you think about when visiting a new place, especially one as beautiful as the Osa. However, when you’re a disease ecologist like my colleague Peter and me, it’s sometimes hard to keep parasites out of your head. Figuratively, that is! So, even before our first trip to Cerro Osa in January 2011, as part of a tropical ecology course with Princeton University, we had begun thinking of ways we could tie in the unique ecology of the Osa with our own research.

Trawling through the wonderfully informative Osa Conservation website, we had eagerly devoured information on the landscape and ecosystem we would be exploring. We found out how Osa Conservation was working to create a biological corridor of rainforest habitat between Cabo Matapalo at one end of the peninsula and Corcovado National Park at the other. That intrigued us. Both of us also have conservation backgrounds, and so we were well aware of the positive benefits of connecting patches of habitat, such as giving predators larger areas to hunt in, and decreasing the chance of inbreeding, which can occur if animals are squished into too small an area. However, we also knew of some theoretical work that our boss, Professor Andy Dobson, had done looking at how corridors, by increasing connectivity between animal populations, might affect disease transmission. Could the Osa peninsula provide us with a natural laboratory for testing some of these ideas?

Our first sunset at the Greg Gund Conservation Center at Cerro Osa, January 2011 (© Claire Standley)

As soon as we piled out of the dusty taxi at the top of Cerro Osa and took in the spectacular view of the landscape, we knew the answer was yes. Straight away we could see how the proposed Osa Biological Corridor, stretching out before us, would provide a crucial habitat link to the rich jungle fastness of Corcovado. However, looking down toward the Pacific we could also see the thin line of the Carate road following along the edge of the corridor, with large tracts of fields and cattle ranches on either side. While the south-eastern side of Corcovado is bordered mainly by beach and mountains, with some ecolodges in between, the corridor would allow for a long boundary of forest with farmland, increasing the amount of geographic area for potential contact between wild and domestic animals. This greater contact could also lead to more opportunities for disease transmission.

Now, a year and three trips to the Osa later, we are well on our way toward testing this hypothesis. At this point, we are focusing on parasites, since they are relatively easily detected and non-invasively diagnosed. For example, simply by collecting fecal samples, we can look for a wide variety of intestinal parasites, such as amoebas and worms. Since it’s easier to get samples, so far we have focused on surveying the domestic animals, and specifically the dogs and cats, living at the various farms and lodges between Matapalo and Carate. However, whenever we walk the trails around Piro and Cerro Osa, we always keep an eye on the ground ahead of us; several times now we have been lucky enough to come across an ocelot or puma scat, which we eagerly scoop up! A key objective for our future research plans is to increase the number of scat samples from wild carnivores, and in order to achieve this, we have started working with a number of the lodges in the Matapalo and Carate area. Since the lodges also have trails through their land, which are used for tours, we have asked the owners to let us know if their guides find scats during their walks, and they have agreed to let us then take the samples away for analysis at Piro. We are very grateful to Kim, Phil, Daniel, Adriana and Andres for their support!

Large puma scat, complete with agouti fur, which we found at one of the eco-lodges near Matapalo in May, 2011 (© Claire Standley)

During our visit to the Osa in May last year, we visited one of these lodges mere hours after a puma had been sighted on the lawn, snatching an agouti as it foraged! Though we were obviously disappointed not to see the cat, finding a large, steaming scat (complete with agouti bones!) on the edge of the forest almost made up for it. And then, just a few weeks ago in January, our patience finally paid off – as we drove back up towards Cerro Osa from visiting the station at Piro, Peter slammed down the brakes of the car, and pointed ahead. There, bounding across the road, was an ocelot! It was the middle of the afternoon, and the cat was kind enough to pause for a moment by the side of the road, staring up at us, as we stood motionless, not daring to breathe, admiring its glossy patterned coat and beautiful face. Then, a few seconds later, it was gone, silently slipping away through the undergrowth.

We know how lucky we were to have such a great view of this elusive species. It also made us realize how much wild animals do need the corridor between Matapalo and Corcovado; a road through an ocelot or jaguar territory leaves the cat vulnerable to being hit by a vehicle, and prey can be more scarce with people and cars around. Our overall aim is to reduce this potential conflict between humans and wildlife, and also protect species from the potentially harmful consequences of parasites. Hopefully, our research will go some way toward understanding disease dynamics in the Osa as it is now, and then be used to minimize transmission in the future, for the improved health of all animals, both domestic and wild.

Claire Standley is a researcher from Princeton University conducting ongoing wildcat research at the Piro Biological Station and surrounding areas in the Osa Peninsula.

If you’re interested in conducting scientific research with Osa Conservation, please contact guidosaborio@osaconservation.org.

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.

Mapping our sighting points from both surveys (Red = dry season, 2010; Purple = rainy season, 2011) shows high-use areas for marine fauna inside the gulf, especially near Puerto Jimenez, the upper coastline of Piedras Blancas National Park and the large river outlets.

As one of only four tropical fiords in the world, the Golfo Dulce is worthy of both exploration and preservation. Much like its terrestrial counterpart, the surrounding Osa Peninsula, the unique oceanic inlet supports an abundance of critical wildlife. Despite this diversity scientific publications about the gulf’s extensive marine life remain limited. So when a proposed tuna farm near the mouth of the gulf gained footing in 2009, I proposed a research project to Osa Conservation to collect baseline data about what marine species utilize the embayment and which areas they frequent.

In 2010 and 2011, with vital support from Osa community members and funding from a Greg Gund Memorial Fellowship, two multi-species sighting surveys were conducted in the Golfo Dulce from a small boat — one during the dry season, and another in the rainy season. I was the principal investigator, but the work could not have been done without the expertise of research assistant and boat captain Jorge Largaespada. Jorge has almost 40 years of experience living in the Osa and working and fishing in the Golfo Dulce. He is a masterful guide on land and by sea and can spot wildlife, especially dolphins, from an astonishing distance.

Throughout both surveys, Jorge and I logged a total of 424 systematic observation hours during 55 days on the water. We recorded 458 sightings for over 38 species of fauna, and our study revealed some interesting things.* What were the highlights? Well, here we begin a blog series to help distill some of our most important findings. In the coming posts I will cover a variety of species from whales and dolphins to sea turtles and sea snakes, and share a few photos along the way. I hope you enjoy this peek at some of the amazing wildlife we observed in the Golfo Dulce.

By Brooke Bessesen

*Should you prefer to read a more detailed account of our study, there are two papers available on the website of Osa Conservation: Project Report and Summary of Multi-Species Marine Sighting Survey in Golfo Dulce, Costa Rica, January–February 2010 and the Rainy Season Extension of The Multi-Species Marine Sighting Survey in Golfo Dulce, Costa Rica, July–August 2011.