Assisted Reproduction and Runt Chicks

Volunteer Blog: Julius
February 17, 2024
The Ara Manzanillo Great Green Macaw (GGM) assisted reproduction program, initiated in 2015, aims to design artificial nest boxes to repopulate this critically endangered species. Before launching this program, we closely monitored the thirty-five re-introduced GGM's that now soared through the Manzanillo-Talamanca region. GGM's act differently in aviary captivity than in natural environments, and it was essential to design a nesting habitat that would further support the re-wilding of this population.
The original thirty-five GGM's were the first released population we'd hoped to inaugurate to establish the first generation of truly wild macaws. Being raised in an aviary - not hatching or ever living in a natural nest - we relied on GGM instincts. To best bridge the GGM's return to the wild, Ara Manzanillo staff designed nest boxes as similar in size and location, surrounded by various food sources as natural wild nests.
The first year of constructing and installing nest boxes was a learning curve. Originally, nests were designed with wood to most closely resemble natural nests. The process of hoisting these heavy nests 30 meters high in a tree to have the wood rot by the next season did not prove to be effective. As with any project, the complexities, and time all took longer than anticipated, but important lessons were learned.
Despite the challenges encountered, we made significant progress in the first year. Nest boxes served to not only protect the macaws from predators and provide nesting habitat but also allow us to monitor for breeding activity.
Everything learned in 2016 prepared us well for the following breeding season. The first year we observed natural selection in GGM parenting. Female macaws lay only one egg a day (up to four eggs per season) resulting in a major size differential between the oldest and youngest chicks. With more mouths to feed, parents favor the strongest chick, leaving the runt. In preparing for the next year, nest boxes were redesigned (adding more than before), we refined the monitoring strategy and decided to prioritize the health of the weakest chicks - which would be hand-raised in the infirmary.

Over the next two years, we continued to hand-raise chicks in the aviary, employing methods to acclimate them to the jungle environment before release (i.e. crack mountain almonds, forage water, and fly). The workload increased substantially in 2018 as we rescued eight chicks, necessitating heightened efforts to meet their needs.

In late 2018, Dr. Donald Brightsmith shared insights from the Tambopata Peru Project, proposing a more nuanced approach to chick care. Instead of immediately removing chicks from the nest, we identified and supported the weakest chick within each nest by providing supplemental feedings. If the primary method did not work, the intervention of a ten-day stay in the infirmary to boost chicks to health was employed, to then return chicks to their original nest.

This innovative strategy implemented in 2019, yielded remarkable results, eliminating the need to raise offspring in the infirmary. Subsequent refinement of this approach progressed, as 2020 marked the first year of rehabilitating the weakest chick in the infirmary for ten days before reintroduction to the nest. GGM parents happily reintegrated the chick, noticing its clear health in being much more plump, and continued to raise and fledge, as would naturally occur.

In 2021, we encountered no rescue cases, attributed in part to the maturation of macaw parents and their growing familiarity with the demands of parenting. The application of Dr. Brightsmith’s methodology in 2022 addressed another critical case successfully, caring for the chick in the nest with additional feedings.

In 2023, a unique situation arose with a smaller chick named 'Lore.' From a nest box of three chicks, Lore was underfed and at high risk, prompting rescue to the infirmary. After Lore's ten-day stay, looking much more full and healthy, we attempted integration into the original nest. Unfortunately, Lore’s parents did not accept the chick back. A few days of close monitoring and supplemental feedings, it was clear Lore was not being integrated.

Lore ended up back in the infirmary again; the next best choice was now to wait for an adoptive nest.

Nobby and Munch were the perfect candidates, as they'd hatched only one chick that season. Lore was placed with the new family and again closely watched to track integration. Within a week, supplemental feedings were no longer required as the adoptive parents took Lore in as their own. Lore flourished, ultimately fledging, and embracing jungle life as a wild bird.

The success of our program underscores the importance of adaptive strategies, informed by scientific insights and hands-on experience, in conserving endangered species and restoring their populations to health.


- Duaro Mayorga, Ara Manzanillo Bird Specialist