World Heritage Identification Number: 928
World Heritage since: 1999
Category: Natural Heritage
WHE Type: Protected Areas & National Parks
Transboundary Heritage: No
Endangered Heritage: No
Country: 🇨🇷 Costa Rica
Continent: Americas
UNESCO World Region: Latin America and the Caribbean
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Area de Conservación Guanacaste: A Biodiverse Haven in Costa Rica
The Area de Conservación Guanacaste (ACG) is a remarkable testament to Costa Rica's commitment to preserving its rich biodiversity. Inscribed as a UNESCO World Heritage Site in 1999, this expansive network of protected areas spans over 238,000 hectares in the northwestern province of Guanacaste.
More to come…UNESCO Description of the World Heritage Site
The Area de Conservación Guanacaste (inscribed in 1999), was extended with the addition of a 15,000 ha private property, St Elena. It contains important natural habitats for the conservation of biological diversity, including the best dry forest habitats from Central America to northern Mexico and key habitats for endangered or rare plant and animal species. The site demonstrates significant ecological processes in both its terrestrial and marine-coastal environments.
UNESCO Justification of the World Heritage Site
Criterion (ix): A striking feature of Area de Conservación Guanacaste is the wealth of ecosystem and habitat diversity, all connected through an uninterrupted gradient from the Pacific Ocean across the highest peaks to the lowlands on the Caribbean side. Beyond the distinction into land and sea, the many landscape and forest types comprise mangroves, lowland rainforest, premontane and montane humid forest, cloud forest, as well as oak forests and savannahs with evergreen gallery forests along the many water courses. Along the extraordinary transect the property allows migration, genetic exchange and complex ecological processes and interactions at all levels of biodiversity, including between land and sea. The vast dry forest is a rare feature of enormous conservation value, as most dry forests elsewhere in the region are fragmented remnants only. Conservation has permitted the natural restoration of the previously degraded forest ecosystem, today serving again as a safe haven for the many species depending on this acutely threatened ecosystem. Major nutrient-rich cold upwelling currents offshore result in a high marine productivity and are the foundation of a diverse coastal-marine ecosystem containing important coral reefs, algal beds, estuaries, mangroves, sandy and cobble beaches, shore dunes and wetlands.
Criterion (x): The property is globally important for the conservation of tropical biological diversity as one of the finest examples of a continuous and well-protected altitudinal transect in the Neotropics along a series of marine and terrestrial ecosystems. The enormous variation in environmental conditions favours a high diversity, with two thirds of all species described for Costa Rica occurring within the relatively compact area. Coexisting in the property, there are more than 7,000 species of plants, as diverse as Mahogany in the lush forests and several species of agaves and cacti in drier areas. Over 900 vertebrates have been confirmed. Some notable mammals include the endangered Central American Tapir, at least 40 species of bat, Jaguar, Margay, Jaguarundi and Ocelot, as well as numerous primate species. Among some 500 bird species are the endangered Mangrove Hummingbird and Great Green Macaw, and the vulnerable Military Macaw. Charismatic representatives of reptiles include the vulnerable American Crocodile and the Spectacled Caiman. Several species of sea turtles occur in the property, with the critically endangered Leatherback nesting and a massive breeding population of the vulnerable Olive Ridley. Invertebrate diversity is extraordinary with an estimated 20,000 species of beetles, 13,000 species of ants, bees and wasps and 8,000 species of butterflies and moths.
Encyclopedia Record: Area de Conservación Guanacaste World Heritage Site
The Area de Conservación Guanacaste is a network of protected areas and a World Heritage Site in Guanacaste Province, in northwestern Costa Rica. The World Heritage Site contains an unbroken tract of tropical dry forest and important habitat for several vulnerable species, including the Central American tapir, mangrove hummingbird, and the great green macaw. Over 7,000 plant species and 900 vertebrate species have been located in the park.Additional Site Details
Area: 147,000 hectares
Number of Components: 1
(x) — Contains most important habitats for biodiversity
Coordinates: 10.85 , -85.61666667
IUCN World Heritage Outlook
The 2025 Conservation Outlook on Area de Conservación Guanacaste reports the following assessment:
Source: International Union for Conservation of Nature (IUCN) · View assessment
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© cyph3r [2], CC BY-SA 2.0 Resized from original. (This derivative is under the same CC BY-SA license.)
World Heritage Research
Discover scientific research and academic studies that deepen our understanding of Area de Conservación Guanacaste from its history and significance to its conservation, management, and contemporary challenges.
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Caterpillar diet breadth in Área de Conservación Guanacaste, a large and diverse Neotropical wildland in northwestern Costa Rica: toxins, silica, aluminum, and sclerophylly
A comprehensive analysis of caterpillar–food plant interactions over nearly four decades in the Área de Conservación Guanacaste (ACG), Costa Rica, reveals that dietary specialization is strongly influenced by plant defenses. The study, based on 431,212 rearing records spanning 7,160 Lepidoptera and 2,489 plant species, found that unpalatable, aposematic herbivores tend to be specialists while highly toxic plant families, such as Aristolochiaceae and Zamiaceae, host many monophagous caterpillars. Biochemical and structural defenses in plants appear to mediate herbivore diet breadth, with defended plant families hosting fewer polyphagous species compared to less-defended ones. The research also highlights that while plant species composition remained relatively stable, caterpillar communities showed significant changes over time, particularly in rainforest and dry forest habitats.
Quicke, D. L. J., Brown, A., Hajibabaei, M., Manjunath, R., Naik, S., Ratnasingham, S., Sones, J., Jacques, B. St., Smith, M. A., Zamora, N., Brown, J. W., Matson, T. A., Miller, S. E., Burns, J. M., Goldstein, P. Z., Metz, M. A., Robbins, R., Solis, M. A., Chacon, I., et al. (2025). Caterpillar diet breadth in Área de Conservación Guanacaste, a large and diverse Neotropical wildland in northwestern Costa Rica: toxins, silica, aluminum, and sclerophylly. Frontiers in Ecology and Evolution, 13. https://doi.org/10.3389/fevo.2025.1647436
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A new genus and a new species in the tribe Eryciini (Diptera, Tachinidae) from Area de Conservación Guanacaste in north-western Costa Rica
Researchers have identified a new genus and species of tachinid flies (Diptera, Tachinidae) within the tribe Eryciini from the Area de Conservación Guanacaste (ACG) in northwestern Costa Rica. The discovery, Santarosamyia woodorum, was made using an integrative taxonomic approach combining morphological analysis, life history data, and DNA barcoding. Additionally, two new species combinations were proposed: Santarosamyia erecta and Santarosamyia unipilum. A lectotype was designated for Exorista loxostegae, and an identification key for the new genus was provided. The study contributes to the understanding of tachinid diversity in Costa Rica, highlighting the importance of comprehensive biodiversity inventories in protected areas like ACG.
Fleming, A. J., Smith, M. A., Hallwachs, W., & Janzen, D. (2025). A new genus and a new species in the tribe Eryciini (Diptera, Tachinidae) from Area de Conservación Guanacaste in north-western Costa Rica. Biodiversity Data Journal, 13. https://doi.org/10.3897/bdj.13.e161853
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Cryptic diversity of Leurus wasps (Hymenoptera: Ichneumonidae: Metopiinae), parasitoids of caterpillars in Area de Conservación Guanacaste, Costa Rica
Researchers uncovered significant cryptic diversity among Leurus wasps, revealing ten new sympatric species within the Area de Conservación Guanacaste, Costa Rica. Initially assumed to be a single species, L. caeruliventris, these wasps were identified through COI barcoding and morphological analysis of hundreds of specimens, each matched with their host caterpillars from the Crambidae family. The study, led by Zuñiga & Valerio, describes these new species—L. billeberhardi, L. henrytownesi, L. hugokonsi, L. iangauldi, L. jesusugaldei, L. marjorietownesae, L. maryjanewestae, L. pammitchellae, L. sondrawardae, and L. wahli—along with an illustrated key to distinguish them. This discovery sheds light on the ecological complexity of these parasitoids, challenging previous assumptions about their species boundaries.
ZUÑIGA, R., VALERIO, A. A., HANSON, P., SMITH, M. A., HALLWACHS, W., & JANZEN, D. H. (2024). Cryptic diversity of Leurus wasps (Hymenoptera: Ichneumonidae: Metopiinae), parasitoids of caterpillars in Area de Conservación Guanacaste, Costa Rica. Zootaxa, 5529(3), 511–531. https://doi.org/10.11646/zootaxa.5529.3.5
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Forty-Five Years of Caterpillar Rearing in Area de Conservación Guanacaste (ACG) Northwestern Costa Rica: DNA Barcodes, BINs, and a First Description of Plant–Caterpillar–Ichneumonoid Interactions Detected
A groundbreaking 45-year study at Area de Conservación Guanacaste (ACG) in Costa Rica reveals unprecedented insights into tropical insect community ecology, documenting over 2,400 caterpillar species and their interactions with 1,352 host plants and 26,000 parasitoid rearings, including ichneumonoid wasps. The research, leveraging DNA barcoding and Barcode Index Numbers (BINs), found no asymptotic trends in bi- or tritrophic interactions after 1983 due to climate change impacts on caterpillar densities. Notably, ichneumonoid parasitoids show a preference for larger-bodied hosts, and introduced plant species are utilized by endemic parasitoids. The study highlights the complexity of tropical food webs and suggests new avenues for ecological research.
Quicke, D. L. J., Janzen, D. H., Hallwachs, W., Sharkey, M. J., Hebert, P. D. N., & Butcher, B. A. (2024). Forty-Five Years of Caterpillar Rearing in Area de Conservación Guanacaste (ACG) Northwestern Costa Rica: DNA Barcodes, BINs, and a First Description of Plant–Caterpillar–Ichneumonoid Interactions Detected. Diversity, 16(11), 683. https://doi.org/10.3390/d16110683
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Revision of Belvosia Robineau-Desvoidy (Diptera, Tachinidae) and 33 new species from Area de Conservación Guanacaste in northwestern Costa Rica with a key to known North and Mesoamerican species
A groundbreaking revision of the fly genus Belvosia (Diptera: Tachinidae) from Costa Rica's Area de Conservación Guanacaste reveals 33 new species, significantly expanding our understanding of this diverse group. This work, part of an ongoing inventory of wild-caught caterpillars across multiple lepidopteran families, provides detailed morphological descriptions, molecular data, and photographic documentation for each species. The study also redefines the genus Belvosia with a comprehensive identification key for North and Mesoamerican species, while proposing new synonyms and combinations that clarify taxonomic relationships. Notably, it records Belvosia canalis from the region and provides updated host information. This research underscores the biodiversity of tropical ecosystems and contributes critical data to conservation efforts in UNESCO World Heritage Sites.
Fleming, A., Woodley, N., Smith, M. A., Hallwachs, W., & Janzen, D. (2023). Revision of Belvosia Robineau-Desvoidy (Diptera, Tachinidae) and 33 new species from Area de Conservación Guanacaste in northwestern Costa Rica with a key to known North and Mesoamerican species. Biodiversity Data Journal, 11. https://doi.org/10.3897/bdj.11.e103667
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Amphibian diversity across three adjacent ecosystems in Área de Conservación Guanacaste, Costa Rica
Amphibian species richness in the Área de Conservación Guanacaste (ACG), Costa Rica, has declined by 45% since the late 1980s, coinciding with global amphibian population declines. Rainforest ecosystems within ACG exhibit significantly higher amphibian diversity than dry forests, with up to three times more species. This study compared contemporary data from five sites—Murciélago, Santa Rosa, Maritza, San Gerardo, and Cacao—to historic records from 1987-88, revealing stark differences in biodiversity. ACG's unique compression of tropical ecosystems into a small protected area offers an unprecedented opportunity to study the resilience—or lack thereof—of these habitats to climate change and disease. The findings underscore the urgent need for conservation efforts to address ecosystem-level vulnerabilities.
Edwards, A. W., Harrison, X. A., Smith, M. A., Chavarría Díaz, M. M., Sasa, M., Janzen, D. H., Hallwachs, W., Chaves, G., Fernández, R., Palmer, C., Wilson, C., North, A., & Puschendorf, R. (2023). Amphibian diversity across three adjacent ecosystems in Área de Conservación Guanacaste, Costa Rica. PeerJ, 11, e16185. Portico. https://doi.org/10.7717/peerj.16185
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Revison of Metaplagia Coquillett (Diptera: Tachinidae) with description of five new species from Area de Conservación Guanacaste in northwestern Costa Rica
A taxonomic revision of the tachinid fly genus Metaplagia reveals five new species from Costa Rica's Area de Conservación Guanacaste (ACG). These discoveries, derived from an ongoing inventory of Sphingidae caterpillars, integrate morphological, molecular, and life history data to redefine the genus and provide a revised identification key for Metaplagia species. Additionally, the study proposes a new combination for Plagiomima latifrons, expanding our understanding of this fly group's biodiversity in ACG.
Fleming, A., Wood, D. M., Smith, M. A., Hallwachs, W., & Janzen, D. (2021). Revison of Metaplagia Coquillett (Diptera: Tachinidae) with description of five new species from Area de Conservación Guanacaste in northwestern Costa Rica. Biodiversity Data Journal, 9. https://doi.org/10.3897/bdj.9.e68598
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