Who We Are

Photograph by: Catalina Mora


Photograph by: Manuel Sanchez

World Migratory Bird Festival

Photograph by: Minor Hidalgo


Conserving Birds And Their Habitats On The Osa Peninsula Through Research And Education

Who We Are

Osa Birds is a charitable non-profit organization dedicated to conserving birds and their habitats on the Osa Peninsula and the southern Pacific coastal slope of Costa Rica through innovative science, education, conservation initiatives and key partnerships that will facilitate species protection.


Osa Birds monitors bird population tendencies to detect possible species declines over time.  We collaborate with public agencies,  non-governmental organizations working to achieve similar objectives, and interested parties to develop conservation management strategies for species protection over the long term.


This is where Education lives, within the communities of the Osa, and it is woven into everything we do!  Osa Birds works to raise awareness of bird conservation and habitat protection within the local rural schools and communities.  Activities include…

Taxonomic Changes 

The new common and or scientific names are highlighted in Bold below for birds found either on the Osa Peninsula or in the southern Pacific region of Costa Rica. For other taxonomic order changes or merges/splits, please refer to the American Ornithological Society (AOS) checklist of North and Middle American birds currently in its 7th edition and its supplements.

Checklist of Birds

Here you will find the newest updated Checklist of Birds for the Osa Conservation Area (ACOSA). The list is long this year as it includes not only the Osa Peninsula but all the ACOSA region including Bahia Ballena, Terraba-Sierpe, Golfito down to Punta Burica.

MoSI has come to the Osa!

Monitoring the overwinter survival of Neotropical migratory birds (MoSI) is an Institute for Bird Populations (IBP) collaborative network of bird monitoring stations across the Americas.  Read on to find out how the US Fish and Wildlife Service is partnering with Osa Birds and IBP to make Osa part of this integral international network in two strategic areas.

Osa Birds Gallery


News and Updates

Featured Bird: Golden-winged Warbler

Featured Bird: Golden-winged Warbler

The Golden-winged Warbler (Vermivora chrysoptera) is a North American Neotropical migratory bird in the family Parulidae that breeds primarily in the United States and overwinters on the Osa Peninsula from approximately October through April.  It is a priority bird...

Featured Bird: Black-cheeked Ant-Tanager

Featured Bird: Black-cheeked Ant-Tanager

This months highlighted bird is very special in two ways because not only is it the bird that launches Osa Birds organizational website, but because it is also the only bird species endemic to the Osa Peninsula.  No other bird carries with it this auspicious...

Welcome Neotrops

Welcome Neotrops

NEOTROPICAL MIGRANTS ARRIVE! The Costa Rican rainy season marks the time of year when a large majority of Neotropical migratory birds arrive to the Osa.  Some birds arrive as early as August such as the Yellow Warbler (Setophaga petechia), and the Black-and-white...