A Great Green Count

Dec 15, 2021

It’s 4:45 in the morning, still dark and a pair of Spectacled Owls (Pulsatrix perspicillata) are vocalizing from the nearby forest. A mere 10 minutes later, the dawn chorus has started, and the first lights allow us to see the six volcanoes and the Caribbean lowlands of Costa Rica. Not five minutes have passed when a number of migratory birds on the southern migration make their debut, including dozens of swallows (Bank, Barn, Cliff, Northern Rough-winged) from the many thousands we will see for the next few hours, when suddenly we hear the first raucous calls from well inside the forest.

Volcan Poás

For years I have enjoyed observing the magnificent Great Green Macaws (Ara ambiguus) across a few localities in the Caribbean lowland rainforests. But this year I had not only the privilege to observe them once again, but the aim was completely different, we were observing and counting GGM’s as part of the annual census, an effort to estimate a minimum population size across Costa Rica. And as part of my work as Bird Program Manager for MRN was to help organize this census, one where we obtained quite important results. For the last three years, MRN along with our conservation partners, the Tropical Science Center have been conducting these populations census.

The Great Green Macaws former distribution included the lowland rainforests along the Caribbean of Costa Rica, with some altitudinal migrations occurring mostly during the non-breeding season, up to around 1000m of elevation. M. A. Carriker in its Annotated List of Birds of Costa Rica (1910), encountered the species, across these lowlands, and considered it less common than the fairly common Scarlet Macaw (Ara macao). But most lowland rainforest in the Caribbean was lost due to deforestation (mainly for cattle ranching, banana, and recently pineapple monocultures), leaving only a small population, which by the 1990’s was estimated to have only 210 individuals.

Great Green Macaws fly overhead
Great Green Macaws fly overhead

Hence, a key point in the conservation of the GGM is to understand the dynamics of the populations, specifically, what is the population size, and how our efforts can help increase the population size, especially since the stronghold of the species (the GGM is distributed from Honduras south to NW Ecuador) are the Costa Rican populations. To answer these questions, we decided to conduct the census during a three-day period, with multiple teams counting the same dates at different locations across northeastern Costa Rica. During the months of September and October, GGM join in larger flocks, hence it is easier (for us) to estimate the population size because they are more concentrated in specific roosting sites. After November, pairs start looking for nesting sites, so the individuals are more scattered across their range and overall harder to count. Despite the species being considered as Critically Endangered, there are still some major gaps of knowledge on the ecology of the species. Some of these we will be aiming to understand in the near future as some of the goals of MRN.

During the census, each counting team visited a previously known location where macaws are known to roost, or, at sites they fly through on their way to roost. At each of these locations the count was made during one afternoon from 16:00 to 18:00, and the next morning from 5:00 to 7:00. This methodology is used to ensure the most accurate count at each point. Furthermore, a dedicated team of people oversaw the count, including the women rangers, and members of other conservation partners such as Reserva Biológica Tirimbina, Reserva Las Arrieras, Reserva Las Brisas, as well as a number of birdwatchers, park rangers, our own volunteers and team members participated.

Two men with binoculars in Costa Rica
Counting Macaws in the distance

Overall, the census was a success. The weather was pretty good which also played on our efforts, and we were able to count at several sites, not included before, which provides us with a more accurate knowledge on the results. With nearly 340 individuals, this is the largest known record of the species that we data for. It suggests the populations has increased since the 90’s decade, which give us hope for the future of the species. Still, while this number is higher than 20 years ago, the number is still small, and we hope that through our conservation efforts to keep on finding more on more birds in the years to come.Hence, we highly appreciate efforts by our funding partners the Tracy Aviary and World Parrot Trust who made possible the conducting of the census.

Continuous monitoring is for effective conservation and management of threatened species. By monitoring and analyzing repeated observations, we can identify changes in the population and betters assess the management progress, as well as identify constraints to the population recovery. Furthermore, obtaining data, and the good management will better allow us to engage more partners including public and private, as well as to better communicate with clear data about the role that local communities can play on the conservation of the Great Green Macaws.

 cesar's portrait

 

 

 

By César Sánchez
Bird Programs Manager

 

 

Three Great Green Macaws flying through the foliage
Great Green Macaws. Photo by Corey Raffel
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