Ara ambiguus, the Great Green Macaw, is the largest parrot in Central America and one of the most threatened parrots in the Americas. The IUCN listed it as Critically Endangered following its 2021 assessment, with a global population estimated at between 500 and 1,000 mature individuals and still declining. Its historic range covered six countries, from Honduras through Nicaragua, Costa Rica and Panama into Colombia and western Ecuador. Across most of that range it is now functionally absent.
Costa Rica holds a meaningful share of what remains. Estimates for the country sit below 300 wild individuals, with something in the order of 25 to 35 breeding pairs. For a bird this large and this loud, those are very small numbers.
A species built around one tree
The Great Green Macaw’s decline is unusually easy to explain, because so much of it reduces to a single tree. The almendro, or mountain almond, Dipteryx oleifera, provides both the nesting cavities the macaws require and a seed that dominates their diet through much of the year. The relationship is close enough that the macaw’s distribution in Costa Rica and Nicaragua largely tracks the distribution of mature almendro.
The scale of those trees is the problem. Nesting almendro average around 32 metres and can exceed 50, and the youngest trees in use as primary nest sites have been estimated at close to 300 years old. A cavity suitable for a macaw is not a feature that regenerates on a management timescale. It is the product of centuries.
Almendro is also a valuable hardwood, dense and durable, and decades of logging removed it from lowland forest across the region before its role in the macaw’s life cycle was widely understood. When a nesting tree comes down, the pair that used it does not simply move next door. There is very often nowhere to move to.
The pet trade and the cost of nest fidelity
Habitat loss did the structural damage, but capture for the pet trade accelerated it. A single chick was worth enough to make nest raiding routine, and the macaws’ own biology worked against them. Pairs return to the same cavity year after year, so a nest, once located, could be harvested repeatedly across seasons. Low reproductive output compounds the effect: these are long-lived birds that raise few young, and a population losing chicks faster than it replaces them declines quietly for years before anyone notices.
What the corridor was meant to do
Costa Rica’s response has centred on connectivity. The San Juan-La Selva Biological Corridor covers roughly 246,000 hectares and was designed to link the Indio Maiz Biological Reserve in southeastern Nicaragua with La Selva Biological Station in northern Costa Rica, and onward to Barra del Colorado and Tortuguero on the Caribbean coast. The intention was to stop the remaining forest from fragmenting into isolated blocks too small to hold a viable macaw population.
Maquenque National Wildlife Refuge, created in 2005, sits at the heart of that plan and protects some of the densest remaining stands of almendro. Alongside the land protection, the practical conservation work has been unglamorous and long-running: legal protection for the almendro itself, reforestation with a tree that will not produce nest cavities for generations, artificial nest boxes as a stopgap, and sustained nest monitoring through the breeding season.
It is worth being honest about what this has and has not achieved. It has not produced a recovery. What it has done is keep nesting habitat standing and keep the monitoring running, which for a population of this size is not a trivial outcome. Conservation for a slow-reproducing bird dependent on 300-year-old trees does not generate quick wins.
Counting a bird that resists counting
Assessing progress is harder than it sounds. Coordinated counts run by the Macaw Recovery Network recorded 653 individuals across five countries in 2022 and 328 in 2023, a swing that reflects survey effort and coverage as much as any real change in the population. Researchers have increasingly turned to passive acoustic monitoring, using recorders to detect the birds’ calls across large areas of forest, precisely because visual censuses of a wide-ranging bird in dense canopy are so difficult to standardise.
The uncertainty is itself a finding. When the plausible range for a species runs from a few hundred to a thousand, the margin for management error is very narrow.
What remains at risk
The core threats have not gone away. Pressure on remaining almendro continues at the edges of protected areas, and illegal capture persists at a lower level. Because the population is small and concentrated, a run of poor breeding seasons or the loss of a cluster of nesting trees could undo a decade of work quickly. Climate shifts affecting almendro fruiting are a further unknown.
Where they can still be seen
Great Green Macaws are loud, conspicuous and considerably easier to locate than their numbers suggest, provided you are in the right forest at the right time. The Sarapiqui region and the lowlands running toward the Nicaraguan border are the strongholds, and the birds are most visible when almendro is in fruit. Local naturalist guides working these sites usually know which trees are producing in a given month, which matters far more than luck. Species accounts published in the Costa Rica Focus bird guide set out where and when the birds are typically encountered, alongside the rest of the country’s lowland avifauna.
Responsible visits are not incidental to the conservation picture. The economics that make standing forest more valuable than timber depend in part on people travelling to see what lives in it, and that revenue reaches the communities inside the corridor.
Why visibility matters
For a species reduced this far, public attention is a resource in its own right. Great Green Macaws have no charismatic megafauna advantage and no obvious economic constituency beyond the forest they need. What they do have is that they are enormous, emerald green and impossible to ignore when they fly overhead. A bird that people can still travel to see is a bird with defenders. That is not a small thing when the alternative is a species that disappears before most people learn its name.
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