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

Habitat Restoration

Osa Birds partnered with Tropical Wings and the Biological Monitoring Group of Rancho Quemado to restore fragmented and degraded habitat.

Citizen Science

Osa Birds monitors bird population tendencies through citizen science and research, and we collaborate with partners to develop conservation management strategies for species protection.

Community Outreach

Education is woven into everything we do!  We work to raise awareness of bird conservation and habitat protection within the local rural schools and communities through workshops and community events.

Taxonomic Redux 2021

In the last several years we have seen many changes to the taxonomy of the birds of the world, and 2021 is no exception! This year the American Ornithological Society’s committee on Classification and Nomenclature of North and Middle American Birds (the NACC) published its new 62nd supplement.

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.


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

Taxonomic Changes to Birds 2019

Taxonomic Changes to Birds 2019

Ver la Traducción al Español Abajo. 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...

Featured Bird: Chestnut-sided Warbler

Featured Bird: Chestnut-sided Warbler

See English Below Simplemente porque es de la famila Parulidae, la familia con más representantes de aves migratorias en la Península de Osa, les traigo la Reinita de costados castaños (Setophaga pensylvanica), la reinita y ave migratoria más común en Osa.  De solo 10...

Recuperando el bosque en el corazón de Osa

Recuperando el bosque en el corazón de Osa

En el proyecto “Estrategias de conservación de bosques y fortalecimiento de emprendimientos verdes en la comunidad de Rancho Quemado, en el área de amortiguamiento del Parque Nacional Corcovado”, actualmente ejecutado por Aves de Osa y financiado por el Canje I de...

2019 International Migratory Bird Day Festival

2019 International Migratory Bird Day Festival

At Osa Birds fifth-annual International Migratory Bird Day Festival, children danced in the streets dressed as flamboyant, richly colored birds, holding feathered wings aloft.  An integral piece that gives flight to this event is the Tropical Wings annual Birdathon,...

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...