Birds, Volunteers and Visitors

It's not too late to sign up for the Holiday Birding Tour!



Space is still available on our Holiday Birding Trip, so join us for spectacular birding through the tropical forests of the Osa Peninsula! This five-day trip includes extensive birding, forest hikes, and nightly talks and excursions with our staff of biologists and conservation professionals.  The trip culminates in the National Audubon Society’s Christmas Bird Count—where you, along with thousands of other citizen scientists throughout the Americas, can participate in the longest running wildlife census to assess the health of bird populations.

The Osa Peninsula is the wildest, yet most under-birded, corner of the country.  It is home to over 460 species of birds, including the healthiest population of Scarlet Macaws in Central America, Red-capped Manakins, Yellow-billed and Turquoise Contingas, and even the Harpy Eagle.  Osa Conservation’s birding trips are led by resident ornithologist, Karen Leavelle, as well as trained naturalist guides who are intimately familiar with the bird species and tropical ecosystems of the Osa.

Your participation in the Holiday Birding Tour directly supports OC’s avian conservation and education programs. We invite you to be part of our mission to conserve the Peninsula’s globally significant biodiversity and we hope to see you on one of these fantastic trips!

For more information on our Holiday Birding Tour, or to see a trip itinerary, please visit our website at For trip registration or questions please contact Emily Angell at or Karen Leavelle at


Yellow-billed Cotinga Conservation and Research

By Karen Leavelle

Female Yellow-billed Cotinga on the day of her tagging Feb. 15, 2011

It really is like no other bird that I have seen. These birds are truly beautiful with movements and behavioral characteristics unique to its species.   These big black eyes belong to a male Yellow-billed Cotinga (Carpodectes antoniae), a highly endangered Costa Rican resident bird species.  It is also know locally as the Cotinga Piquiamarillo.

He is just one of a dwindling number remaining here in the southern pacific coastal slope of Costa Rica and hopefully the north pacific coast of Panama.  I say hopefully because historically this species was found on both sides of the border inhabiting coastal mangroves and adjacent mixed rainforest.  Loss and degradation of habitat for this regional endemic bird is the main cause of its decline with a population estimated to only be somewhere between 250 – 799 birds remaining.  Because of the several intact mangroves that are found around the Golfo Dulce and up around Térraba-Sierpe National Wetlands of Costa Rica, the Osa Peninsula and its environs now appears to be this species one and only remaining stronghold.

The male and the female look quite different; the female sporting a mottling of gray, white and black on her wings and back while the male is a stunning pure white with slight hints of soft light gray all over.  Its signature yellow beak with its central black stripe is what sets it apart from the Snowy Cotinga, its closest relative found on the Caribbean slope of Costa Rica.  You won’t find much yellow in the females’ beak however except along the base of the bill.  The fledglings look like mom while the sub-adult males, probably not much older than one year, have that in-between look going on.   As far as vocalizations are concerned any form of communication that may be used between individuals is not readily apparent to those of us on the ground.

Now picture about 6 male Yellow-billed Cotingas in a single tree snag branching out in all directions each male swooping down and back up into an adjacent tree, mostly leafless or semi-leafless, all in an effort to gain the attention of a nearby female.  Just imagine a gymnast on parallel bars.  This is the courtship display and is also a movement that is seen by males throughout the breeding season.   Once the female has made her choice it is thought that she then takes on 100% of all parental duties.  The males spend their time feeding and returning to their core areas to make their territorial rounds day in and day out.

So let’s go back for a second and let me reiterate something before moving on.  There may be as few as 250 Yellow-billed Cotingas remaining on the planet, not found anywhere else!

Because of this, Friends of the Osa in partnership with the American Bird Conservancy took on the task of investigating this species actual distribution in a study completed in 2009, and a more specifically aimed study currently looking at its habitat use patterns and its spatial and temporal movements during the reproductive and non-reproductive times of the year.

Male Yellow-billed Cotinga 2011

We are able to determine the birds movements via radio telemetry.  We have placed small radio transmitters on three cotingas, one adult female and two adult males from a small population which breeds in the mangroves of Rincon de Osa located on the north end of the Osa Peninsula along the Golfo Dulce.  We have been able to follow all three birds around their breeding grounds via their radio frequency signals since their capture in mid February.

Essentially what we have done is take geographic satellite positions (waypoints) of birds locations throughout the day using a hand held GPS unit.  With an accumulation of waypoints we are now able to determine each individual’s home range which is basically the size and configuration of the area the bird occupies or uses.  As the birds disperse into other areas of the peninsula during the winter months between June and December we will track their movements and map the areas used in order to more precisely determine which areas are in need of protection and possible conservation measures.

Not only will results from this study reveal important patterns of movements throughout the year of the Yellow-billed Cotinga, it will also serve to safeguard sensitive mangrove habitats and better protect other species which also rely on the mangrove and rainforest ecosystems unique to this part of the world.

YBCO with his unique black bill stripe

Other species to keep an eye on that specifically rely on mangroves are the Mangrove Hummingbird which is a Costa Rica endemic species and the Prothonotary Warbler, a North American  migratory songbird.

We would like to take this opportunity to thank George and Luke Powell for their tireless assistance in capture techniques (including net construction and radio harness placement) as well as home range data analysis, and to Luis Vargas for his energy and tenacity during many weeks of work towards what ended up being a successful capture and beyond- high tides and all! Thanks to Manuel, Courtney and Christina for all the long hours climbing mangroves and wading through rivers.  We would also like to thank the owners of El Chontal Cabinas, and ADEPAS for providing us lodging and the staff of Friends of the Osa for constant support and feedback.  Thanks also goes out to Optics for the Tropics for their donation of binoculars for field staff and to Andrew Judd Pruter of Psycho Tours for supporting this project with climbing equipment used during the cotinga capture.   And this list is growing…

Please keep your eye out for more information on the Yellow-billed Cotinga project…


Featured Bird: White-crested Coquette

Male White-crested Coquette

Of all the hummingbird species, the coquette males that are most highly adorned with ornate feathers that are there to likely help in territorial defense and enhance species recognition.  The White-crested Coquette (Lophornis adorabilis) is the only coquette found here on the Osa Peninsula and is regionally endemic to south western Costa Rica and Western Panama.

The male of this species, which is also sometimes called Adorable Coquette, is known for its white crest and long green cheek tufts and may be arguably one of the most sought after birds to see when one visits this region.  They wander through forests high in the canopy and low along forest edges feeding on the nectar of flowering Inga, Vochysia, Stachytarpheta and Lonchocarpus plants and will also take small spiders and insects.  They hover with their tales cocked upward while feeding.

Male White-crested Coquette showing cheek tufts.

While courting a female the male will make short arcs side to side not much more than about a foot in either direction in front of the female.  He uses his colorful good looks to defend his flowers within his territory and the female takes on all nest duties with no help from the male.  The small lichen covered nest holding two minute white eggs is placed on the fork of a branch along the forest edge or a clearing and is not very well concealed.

They are said to be found from 300 meters up to 1220 meters but we have seen them here at the Piro Research Center which is near sea level as well as up along the Greg Gund Conservation Center’s northern border at Cerro Osa which sits at about 300 meters all within the last month.  At the moment they are engaged in reproductive behavior which takes place during the rainy season from December to February with courtship seen as early as October.   The male will lose his ornate regalia when the breeding season is over.


Featured Bird: Turquoise Cotinga

Male Turquoise Cotinga. Photo by Ulises Quintero

This week as promised I am bringing you the Turquoise Cotinga (Cotinga ridgwayi).  This is definitely one of those species of bird that makes you go “WOW” when you see it.  This is also one of Costa Rica’s most sensitive species to loss of forest habitat.  BirdLife International has this Cotinga species listed as Vulnerable which puts it one step away from be considered Endangered.  It is a regional endemic only found on the Pacific slope of central and southern Costa Rica and western Panama.  Its population is estimated to be between 2,500 – 10,000 birds and declining.

So why the decline?  As with many species, the Turquoise Cotinga is faced with deforestation and severe habitat fragmentation.  This coupled with an already naturally small range makes it difficult for the Cotinga population to remain stable.  This is also true for its closest relative the Yellow-billed Cotinga also found here on the Osa Peninsula whose population is estimated to be much smaller between 250 – 1,000 birds (more on this species in the weeks to come!).

Because of the Turquoise Cotinga’s conservation concern and its rarity, it is a special occasion when we see one.  Now you must know there are certain areas on the Osa Peninsula where this bird is quite common such as Carate and Corcovado National Park and folks flock to these areas to see them.  Since we at Friends of the Osa are in the middle of our seasonal avian monitoring we have had the distinct pleasure to have encountered several Turquoise Cotingas in the last two weeks within our monitoring points and just up the road from the Greg Gund Conservation Center on Cerro Osa.  It is possible that Turquoise Cotingas are more common than once thought on Friends of the Osa property especially outside of the breeding season when they are seasonally migrating in search of food resources.

This passerine species is found mainly in the canopy of humid rainforest and secondary growth and can also be seen along forest edges and in tall trees within shade grown coffee plantations.  They will wander throughout the canopy of wet forests and are known to rest on high exposed perches.  They consume the fruits of fig trees, Cecropia and parasitic mistletoe Psittacanthus and will go down low to gather pokeweed berries Phytolacca in clearings on occasion.  In case you were wondering it weighs in at about 50 grams, just under the size of a Red-winged Blackbird.

The males and females apparently do not form pair bonds.  The males gather in group display leks to attract females.  The female then builds the nest and rears the two young all on her own.  Nesting takes place between January and May.

Conservation measures are to investigate current distribution and discourage the conversion of shade coffee to full sun grown coffee.  Unfortunately very little information is available on the behavioral ecology of this species so the more we learn the more we will bring to you.


Birder's Challenge Response

Riverside Wren Nest. Photo by Jim Tamarack and Cheryl Chip

A few weeks ago I posted a birder’s challenge question where I asked you to tell me how the Riverside Wren (Thryothorus semibadius) was positioned in its nest (go to the archived story here).  Here is the recap and your responses.

Since Riverside Wrens are known at times for roosting inside their nests during all seasons of the year with sometimes two or three individuals at a time we wondered about this particular wren when our neighbors Jim Tamarack and Cheryl Chip showed us this photo.  It was taken at night during the month of December.  Its position wasn’t immediately obvious so I thought I would pose the question to you.  What is this bird doing and how is it positioned in the nest?

Everyone agreed that the black-and-white striped feathers are the breast feathers and that the rufous part at the top is the head facing back and to the side while keeping an eye on, well…Jim and Cheryl’s camera for starters.  It was also the general consensus that, due to the photo session taking place, this posture was a likely a defensive one as well as a protective camouflage while in the vulnerable place it was in inside the nest.  One person commented that they could actually see the feet perching on the branch and that the bird is standing up (sort of) with its belly facing the door.  If you zoom in you can see the feet.

Riverside Wren. Photo by Gianfranco Gomez

On a lighter note someone suggested that it was either a defensive posture or the bird practicing some yoga.  For many people who visit the Osa Peninsula on vacation this wouldn’t be out of the question, but Riverside Wrens…?

I think that everybody had it right but it also begs the question; how many species build roosting nests or use old breeding nests to roost in later?  It is not uncommon for cavity nesting birds to also roost in the cavity during the non-breeding part of the year. For birds that build covered nests here in the tropics it could actually be a good way to shelter from the often times torrential downpours we have here in the winter rainy season.  It is an interesting question and one to look into a bit further.

Keep an eye out next week for a little bit about the Turquoise Cotinga.


International Migratory Bird Day & The Power of Partnerships

Have you ever sat and marveled at the wonder of bird migration; the journey that birds undertake between their winter and summer homes?  Well if so, you’re not alone, and it is a cause for celebration!  Each year hundreds of thousands of people gather to celebrate International Migratory Bird Day (IMBD) in support of migratory bird conservation.

You may be asking yourself, why a post on a day normally held in May.  Aha, that all depends on where you are in the hemisphere.  Because there is more than one officially recognized date, everyday, including today, is Migratory Bird Day.  Read on as I explain…

International Migratory Bird Day is officially recognized on the second Saturday in May in the US and Canada in celebration of migrants coming home to breed, while in Mexico, Central and South America and the Caribbean IMBD is celebrated on the second Saturday in October when migrants are returning home for the winter.   Here in Costa Rica IMBD is actually celebrated on the second Saturday in April.  But because migratory birds have been arriving on the Osa for the past several weeks we thought it important to pay homage now as well!

There are almost 350 species of birds that migrate between their nesting grounds in the north to their wintering grounds in more favorable climates somewhere south.  Of course not all birds make such dramatic journeys.  Many species migrate locally, regionally and elevationally such as many do here in the tropics, and so this day is for them as well.

Wood Thrush.  Photo by DH Freriks 2009

Migratory birds are important to us in many ways.  Many of them are the songsters that fill our northern forests and backyards with their melodious song every spring marking the change of the new season and the new life that it brings.  Migrants are important ecologically as they are the consumers of insects, many of which are pests, and they are also important to the tourism industry of many economies both temperate and tropical.  Here in their tropical wintering grounds, places like the Osa Peninsula provide an important home during the non breeding months of the year.

Unfortunately many migrant bird species are declining facing many threats on their wintering and breeding grounds as well as on their migratory routes.  International Migratory Bird Day was thus created as not only a day to celebrate migrant birds but as a call to action in their conservation through partnerships.

American Redstart. Photo by Karen Leavelle 2004

Since 1993 the Smithsonian Migratory Bird Center, Partners in Flight, the National Fish and Wildlife Foundation, the US Fish and Wildlife Service amongst many others have come together in science and conservation for the protection of migratory birds.  Each year hundreds of organizations hold activities and celebrations all focused around a particular theme.  This year’s theme is The Power of Partnerships giving attention to the fact that avian conservation can only happen through strong partnerships across the globe.   Twenty species are highlighted this year to include the Wood Thrush (Hylocichla mustelina), the Golden-winged Warbler (Vermivora chrysoptera) and the American Redstart (Setophaga ruticilla), all species in decline found here on the Osa and shown here as well thanks to the artwork of Bob Petty.  Visit for a list of each species and more information on each species’ conservation status and the partnerships formed to help protect them.

We here at Friends of the Osa are celebrating now in our own way by conducting an avian monitoring program set up specifically to follow US Fish and Wildlife Service protocols in order to monitor the population status of both resident and migratory birds and to make our data available to all organizations interested in targeting conservation measures for specific birds in decline.   We are also working with Partners in Flight in data analysis and dissemination of results to the bird community.

The three species shown here are only a few of those suffering from population declines but it is our hope that through a strong monitoring program and strong partnerships we can protect those species that count on Costa Rica’s Osa Peninsula for their safe winter harbor.

Orioles and Ocelots: Wisconsin’s Costa Rica Connection, authored by Craig Thompson who organizes conservation birding trips to the Osa Peninsula, provides a great explanation of how these north-south partnerships are strengthening bird conservation.

Stay tuned April 9th 2011 for official Costa Rican International Migratory Bird Day science and educational activities.  IMBD is coordinated by Environment for the Americas.  More information can be found at


Featured Bird: Pale-billed Woodpecker

Pale-billed Woodpecker Male. Photograph by Alan Dahl

Of the eight woodpecker species that are found on the Osa Peninsula, the Pale-billed Woodpecker (Campephilus guatemalensis) is the largest with a length of 35 cm (14 inches) rivaling only the superficially similar, and range overlapping Lineated Woodpecker (Dryocopus lineatus).  In fact, the Pale-billed Woodpecker is most closely related to the extremely elusive north temperate species the Ivory-billed Woodpecker, both belonging to the same genus, Campephilus.  This species ranges from southern Mexico to Western Panama.

The Pale-billed is distinguished from the Lineated by its fully red head.  Only the female, pictured here, has a black center crown, neck and throat while the male’s head is completely red.  When their bright red crest stands up on end they look like the punk hoodlums of the bird world.

These birds are actually quite common here on the Osa and can be found right here at the Osa Biodiversity Center anywhere between the Greg Gund Conservation Center and Piro Research Center.  There is a pair that is excavating a nest right now in the month of September in our NRDC forest restoration plot located approximately 6 meters up in a snag.

Pale-billed Woodpecker Female. Photograph by Gianfranco Gomez

The nesting period typically ranges from August to December.  Pale-billed Woodpeckers excavate their own nests, but are sometimes taken over by Araçaris while under construction.  Both parents incubate the two eggs typically layed and also care for their young.  They roost in large cavities similar to those used for nests and can use the same cavity for roosting for several months.

They commonly eat the large larvae of wood boring beetles excavated from the trunks and limbs of large trees and dead and decaying wood.  When not eating beetle larvae they have been known to take fruit from Melastome trees.

Sounds include the vocal “bleating” sound and the non-vocal drumming “double-rap” similar to that of other Campephilus species such as the Ivory-billed Woodpecker.  The NRDC pair is in the habit at the moment of counter-rapping with its nearest neighbor who is only about 100 meters away.

We would like to thank Alan Dahl from Focused on Nature photography and Gianfranco Gomez from the Drake Bay Rainforest Chalet for allowing us to show off their amazing photographs of the Pale-billed Woodpecker.


Featured Bird: Chestnut-backed Antbird

Chestnut-backed Antbird. Photo by Alan Dahl

Chestnut-backed Antbirds (Myrmeciza exsul) are common residents of the Osa Peninsula and one of the most abundant species found here.  It is difficult to walk outside here at Friends of the Osa’s Osa Biodiversity Center and not hear two or three individuals counter-singing.  Often times when the rest of the forest has become fairly quiet you can always count on a Chestnut-backed Antbird to let you know that all is as it should be.

The signature look of three species of Antbird found on the Osa Peninsula of Costa Rica is the blue orbital skin (the skin surrounding the eye).  The Chestnut-backed Antbird is one of these species and is distinguished from the others by its slate colored head and chestnut back.  The other antbird that you are likely to see here with the blue orbital skin is the Bicolored Antbird, but it is distinguished by its white neck and belly.

As you can tell by the name, Chestnut-backed Antbirds follow army ant swarms; however, they only do this occasionally and are not considered obligate, or professional, army ant followers.  They are strongly associated with the dark undergrowth of wet tropical forests within dense vegetation especially near overgrown treefalls or dense thickets.  They often join mixed species flocks but won’t necessarily move along the forest with the flock, but will rather join them while ant swarms are moving through the dense thickets in which the Chestnut-backed Antbirds are found.  Once the army ant swarm or the mixed species flock is gone, they will remain in the undergrowth found in their territory.  Many tropical birds follow army ant swarms to pick up insects flushed by the ants, not to eat the ants themselves.  Chestnut-backed Antbirds mainly hop along very low lying perches or along the ground and peck their prey, which mainly consists of insects and spiders from the ground or near the ground vegetation.

Chestnut-backed Antbird. Photo by Gianfranco Gomez

They are territorial throughout the entire year and both the male and female sing duets back and forth to each other and in response to their nearest neighbors.  When disturbed, they will pump their tail downward, droop their wings, and fluff up their feathers.  They nest low in small bushes or debris during the rainy season from April to October.  They usually lay two eggs and both parents incubate and tend to their young.

We would like to thank both Alan Dahl from Focused on Nature and Gianfranco Gomez from the Drake Bay Rainforest Chalet for allowing us to showcase their photographs.


Birder's Challenge

Riverside Wren nest by Cheryl Chip & Jim Tamarack

For those of you who may remember, I posted a feature on the Riverside Wren (Thryothorus semibadius) back in April.  It was one of my first postings for the then new Friends of the Osa’s blog The Osa Chronicles and a few of you commented on both the nature history and photography by Gianfranco Gomez.

One of the species ecological behaviors I wrote about was of reproduction and nesting.  When I spoke about the nest of the Riverside Wren this is what I said:  “Nests are bulky globe structures with a roof and a vestibule (so to speak) not only used for raising young but also for sleeping at night any time of the year by either one individual or as many as possibly 3.  This species can be found nesting from December to August, nine months out of the year!”

Not long after this posting some friends and residents of the Osa Peninsula Jim Tamarack & Cheryl Chip saw the posting and sent me this photo they took of a Riverside Wren roosting in its nest at night near their home.  This photograph was taken in the month of December, but it also could have been taken any time of the year.

Riverside Wren at Drake Bay

Now, the position of this bird has had many of us puzzled for some time so I am inviting commentary from you all.  It looks like the bird is camouflaging itself in the nest, but how?  The Riverside Wren has barred black-and-white stripes only on the breast and belly while the back is solid rufous.   It’s as if it were laying on its back.  Are there two birds here?  Is this the Riverside Wren?

OK birders, its time to chime in.  I am waiting for your opinions and comments.

Birds, Community Outreach

Ornithological Union of Costa Rica Conference

Karen Leavelle presenting the Yellow-billed Cotinga spatial distribution project

The Costa Rican Ornithological Union’s second annual conference was held July 28 – 30th 2010 in the school of biology at the University of Costa Rica in the capital of San Jose.  The conference was dedicated to Daniel Janzen and his pioneering work in the field of conservation and reforestation in Costa Rica over the last several decades.  Attendees present represented national and international organizations working hard at avian science and conservation throughout the country coming together to share common interests in the more than 830 resident and migrant bird species found in this tropical landscape.

Friends of the Osa’s avian ecologist Karen Leavelle was in attendance to present a poster outlining the upcoming Yellow-billed Cotinga radio telemetry project slated to begin at the end of this year.  Also in attendance were Liz Jones and Abraham Gallo to present their findings from a two year study looking at the current distribution of the Yellow-billed Cotinga, Black-cheeked Ant-Tanager and the Mangrove Hummingbird all of which are endemic species considered to be endangered by BirdLife International.  This project was supported by Friends of the Osa, the American Bird Conservancy and the Evergreen Foundation producing vital information highlighting the conservation status of each species and the importance of the rainforest and mangrove habitats to species survival remaining on the Osa Peninsula and surrounding areas.

Elizabeth Jones presenting Yellow-billed Cotinga project results

The Yellow-billed Cotinga project was born out of Liz and Abrahams results on the species current distribution.  This project will focus on tracking Cotingas throughout the Osa Peninsula in order to determine the spatial and temporal distribution of a population of Cotingas from the Rincon area.  Essentially this project will show temporal habitat use and the spatial movements of the birds between feeding, nesting and roosting areas.  Information gained will indicate forested areas in need of protection for this species and others that also depend on the same habitats for their survival.  Keep your eye for more information on this project as its December date approaches.

The conference itself and Friends of the Osa’s participation proved to be important as a manner of disseminating information to a national and international ornithological audience on project results, upcoming studies and our role on the Osa Peninsula in avian science and conservation.

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