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Harpy Eagle reintroduction in Belize

Update 4 on the Harpy Eagle Restoration Program.

July 2004

Sharon Matola, Belize Coordinator


This is the most exciting Update since the start of the Belize Harpy Eagle Restoration Program. The eagles, still at their initial release site at Las Cuevas Research Station (LCRS), are clearly showing signs of steady independence.

Besides documentation of their hunting, the Harpy Eagles are also moving out further and further from the hack site. Dispersal is a necessary activity, and shows that gradual movements away coincide with becoming further independent from their beginning site location at LCRS.

I have received questions about the general procedures followed in the Belize Harpy Eagle Restoration Program, BHERP. To address this, I have included a summary of the procedures used and then I have followed this with a more tailored briefing about the Belize program itself. As ever, please feel welcome to contact me with questions or comments .


The Harpy Eagle, Harpia harpyja, could, historically, be found in healthy populations from southern Mexico to northern Argentina. Due to extensive deforestation, human persecution, and habitat fragmentation throughout its range, populations have been drastically reduced and Harpy Eagles are considered to be nearly extinct in Central America (Howell and Webb 1995). Current sightings of Harpy Eagles have been confirmed in Panama, Costa Rica, Belize and Nicaragua. However, no known breeding pairs exist in these countries at this time.

The Harpy Eagle is believed to be the most powerful raptor in the world. It is the largest eagle in tropical America, weighing 18-20 lbs. Its wingspan exceeds two meters. Unlike many other raptors, Harpy Eagles do not soar high. Nor do they fly long distances. Instead, they travel relatively slowly, moving from tree to tree through the forest. They are top predators and can live for over 50 years in captivity. Harpy Eagles require large areas of intact lowland forest in order to successfully hunt and reproduce. Because of this, these raptors are considered to be an “Umbrella Species” – in order to protect Harpy Eagles it is necessary to conserve large tracts of forest and these same forests contain some of the highest biodiversity on earth.


Throughout the range of the Harpy Eagle, the forests supporting their populations are usually less than 800 meters in height. Undisturbed forests are ideally suited to their needs. They have also been observed in areas with minimal sustainable use, as well as in second growth forests. Most important, the habitat requirements for Harpy Eagles include the presence and availability of prey. Also necessary is an abundance of large, emergent trees in which to build their nests.


The diet of the Harpy Eagle consists mostly of a variety of medium-to-large sized arboreal animals. This also includes other birds. Sometimes they will prey upon mammals and reptiles that live on the forest floor.


1. The Harpy Eagles are captive-bred in Panama by the Peregrine Fund at the Neotropical Raptor Center. They are handled no more than 4 times: A. when moved from the lab to the imprinting chamber. B. then from the imprinting chamber to the flight pen. C. followed by a move to the hack box. D. finally, when they are relocated from the hack site to the final release area. (one exception is for recapture to change radio-transmitters)
2. After hatching, the chicks are kept in a lab where they are fed and cared for during the first weeks of their lives. At 30 days old, they are placed into an imprinting chamber – a wooden box that is in full view of an adult Harpy Eagles. This allows the young birds to imprint on their species.
3. At around 120 days of age, they are then moved to a big flight chamber. This allows them the room to fledge naturally and to exercise their wings.
4. At around 150 days of age, and after they spend about 4-6 weeks in the flight chamber, they are captured, weighed and radio transmitters are placed on the birds. They are then ready to go to their hack site – a modified chamber built at a pre-selected, isolated location in a forest habitat (Las Cuevas Research Station, for this particular project).

A wild Harpy Eagle begins to hunt at approximately 1 year of age. The Peregrine Fund has also found that this is similar to captive-bred and released eagles in Panama. Once a released eagle is hunting, and does not require constant monitoring, it will be trapped, then relocated to a final release area. For the Belize Harpy Eagle Restoration Program this area is the Rio Bravo Conservation Management Area, in northwestern Belize, under the management of Programme for Belize.


The principal consideration for release site selection includes habitat structure, prey abundance, logistics to the work site, and relative isolation from human activity.


A small radio transmitter is attached to the birds to allow biologists to track the Harpy Eagles once they are released. The transmitter is glued with epoxy and cable-tied to the upper (proximal) ventral part of the deck feather (middle tail feather), and will be attached to the bird until it molts. This normally takes a year.


The Harpy Eagle monitors place food for the birds when it is dark, either at night, or in the very early morning hours before dawn. At the hack site, the attendants always approach the hack box from the back so that the birds do not see human activity.

The females usually consume more than the males. The eagles receive one rat each day. Dead wildlife is NEVER given to the Harpy Eagles. The cause of death of most wildlife cannot be determined, therefore, it is risky to feed Harpies animals which may have been poisoned, or died from a disease.


In the wild, young Harpy Eagles generally fledge between 6 and 7 months of age. Given this, the young Harpy Eagles are usually released from the hack box between 175 and 210 days of age. Work both in Panama and Belize has shown that some of the eagles may come out of the hack box within seconds. Others may stay in the hack box for hours. The birds are constantly monitored.


A feeding tree is basically a Harpy Eagle feeding station located away from the hack box. This is done due to three possible scenarios. 1. If the eagle leaves the hack site and does not return within 7-10 days, monitors must set up a tree for the bird to ensure that it is eating. In Panama, it has been experienced that Harpy Eagles sometimes will not return to the hack site and will feed only at the feeding trees. 2. It is done to lure Harpy Eagles away from the hack box. This ensures that the release area does not become “crowded”. Also, it allows the release of more birds at one site than normally would be possible. 3. If a Harpy Eagle appears to be flying/dispersing, it can be used to keep the bird in one general area.


The young eagles will begin to range from the hack site and may only return to the hack box every few days. This does not mean that they are independent or dispersing. This is a natural part of their exploratory nature. It exposes them to prey sources, other raptors and also, unfortunately, possible fatal experiences. In the wild, Harpy Eagles are dependent on their parents for at least 2-3 years after fledging. Therefore, observing tracking and identifying each eagle is done with diligence.


Experience from Restoration work in Panama has shown that 3-4 possible scenarios exist as potential hazards. First, the birds could become increasingly used to humans as their food provider and will not learn to seek and kill prey. If this happens, they may never learn to hunt and could potentially starve to death. While possible, this is unlikely to happen. Second, it is possible that the released birds may fall prey to another predator. This is most likely to occur once the eagles are hunting for themselves, as they can be caught on the ground while eating their quarry. Very little can be done if this occurs and some natural mortality must be anticipated. Third, if a resident Harpy Eagle pair is in the released Harpy Eagle area, they could possibly kill the birds – again, an unlikely scenario to happen as part of the Belize Harpy Eagle Restoration Program. And the fourth possible hazardous outcome would be a threat from hunters who might shoot and kill the birds.


By using radio-telemetry to locate an eagle and a trap with bait, any released Harpy Eagle can potentially be captured. This is done by experienced personnel and only in circumstances when the bird’s life is at risk, or if there is an immediate need for relocation. Moving of the eagles from the initial release site to the final release area will take place by the fastest and least stressful means of transportation. The eagles will be placed in large, covered kennels and escorted by a biologist at all times. The relocation area would be a large, suitable habitat for Harpy Eagles, with potential prey items and emergent trees.. Ideally, there would be a non-existing or low-density population of wild Harpy Eagles to avoid possible intra-specific competition. Marta Curti of Peregrine Fund about to release Harpy Eagle


The Belize Harpy Eagle Restoration Program, BHERP, is part of a larger 25 year effort aimed at restoring Harpy Eagles to a sustainable population throughout the MesoAmerica Biological Corridor, MBC. Over this period of time, about 60 eagles are expected to be bred in captivity at the Neotropical Raptor Center in Panama, and about 8 new breeding pairs in key locations in the MBC will be established.
In Belize, this project aims to restore lost or depleted populations of Harpy Eagles using captive breeding and release methods that have been used to restore other endangered raptors, such as the Peregrine Falcon and the Mauritius Kestrel. The BHERP serves to empower biodiversity conservation efforts by using the Harpy Eagle as an umbrella species. Sustaining Harpy Eagle populations in a forested landscape rich in its biodiversity, maintains these ecosystems in a healthy state.

In the BHERP, it is aimed to annually release 4-6 Harpy Eagles in the Rio Bravo Conservation Management Area. A thorough assessment of the forest was undertaken to determine the status of the prey base. Overflights were accomplished, as well, to obtain a visual understanding of the amount of forest area available for this important final release. These fly-overs were made with assistance from LightHawk. Most of these eagles will be released at approximately 2 years of age and will be independent of human care. At around 5 years of age, a Harpy Eagle reaches sexual maturity. Given this, it will be another 3 years before the released eagles are ready for breeding. As these first few years are critical to the survival of the eagles (and as with most raptors, a high mortality percentage should be expected, this has been documented at 60-80%), a high number of Harpy Eagles will need to be released in order to achieve a healthy number of adult breeding pairs.

All of the released Harpy Eagles will be fitted with a VHF radio transmitter. This allows their monitors to locate them once they begin to disperse from the release area. In addition, a small sample of birds will be fitted with satellite transmitters (PTT). These units will assist in the tracking of the birds and will allow a more precise and regular understanding of their movement patterns.

To maximize the success of the release project, a crew of 2-3 biologists will be part of the program. They will monitor the behavioral patterns of the released eagles. The information gathered will allow for making necessary changes in the release strategies. The biologists will be trained in radio tracking, observations and data collection techniques. This training will occur prior to the release of the Harpy Eagles. It will continue once they are in the field. To assist, supervisors will conduct semi-regular evaluations in order to insure that the work is being carried out as needed. The country coordinator of the BHERP will also make visits to the project site and provide assistance.


In June, the 4 Harpy Eagles were trapped and new radio-transmitters were placed on each bird. This will enable the biologists monitoring the birds to obtain continual data on their ecology.

The Harpy Eagles initially released at LCRS, have shown to be dispersing further and further away from their original site of release. This mirrors the Panama project, and provides a strong confidence level that the released birds will follow a general time frame of release-to-dispersal behaviour.

In Panama, captive-bred and released Harpy Eagles have shown to begin hunting independently at approximately 1 year of age. This, too, has been reflected in the BHERP. Prey documented by the Harpy Eagles to date include:
- Kinkajou, Potos flavus
- Anteater, Tamandua mexicana
- Opossum, Didelphis marsupialis

Spider monkey, Ateles geoffroyi, and Howler monkey, Alouatta pigra, are both present in the area, but have not been preyed upon by the Harpy Eagles.


“Panama”, the captive-bred Harpy Eagle at TBZ, continues to be a popular attraction and education exhibit. His lack of shyness around human visitors adds to the value of his serving as an ambassador for the released Harpy Eagles in Belize.

A new sign has been erected by his exhibit explaining the probable prey choices for the released birds in Belize. A few times, it has been overheard in presentations given by tourguides to their clients that “Some people are against Harpy Eagles coming back to Belize because they will decimate our Howler monkey populations”.

The sign explains that these birds seek, for good reason, solitary arboreal prey. Taking an Anteater or a Kinkajou is far less risky than flying into a troop of Howler monkeys for a meal. It has also been shown that male Howler monkeys will attack back, and this is a threat which can greatly endanger a Harpy Eagle (Touchton 2002). However, at some times of the year, food resources for primates are at a hard decline. When this occurs, the weaker members of the troop will often fall behind. These individuals are likely to fall prey to a predator. This is called “how nature works”.


Unfortunately, there has been a marked increase of Guatemalan incursions over the border and into the area around LCRS. Their main purpose for entering Belize is to harvest “Xate”, the leaf of a Chamadorea species of palm that is widely used in the floral industry. However, they hunt, and they have caused disturbances at LCRS. It is viewed that their increased presence puts the released Harpy Eagles at serious risk. At this time, a removal strategy is being considered and the aim is to get the 4 birds to their final destination at Rio Bravo Conservation and Management Area, as soon as possible.

A lack of support funds is still causing problems for the BHERP. Grants are pending, however, the project continues to be hampered by funding gaps.

Thanks to a grant received by the United Nations Development Programme, Global Environmental Facility Small Grants Program UNDP/GEF/SGF, last year, our Education Department has put forward a dynamite program which has seen an increase of awareness about the Harpy Eagle communities in Belize.

The targeted communities have been in the Belize and Orange Walk Districts, and the villagers have been Creole, Mestizo and Mennonites. These villages lie closest to the forests of Rio Bravo, the final destination site for the 4 Harpy Eagles presently at LCRS.

Since hunting has been a major cause of the reduction of Harpy Eagle populations throughout Central America, informing these communities about the important role the Harpy Eagle plays in the local ecology becomes critically important. A total of 23 presentations were made throughout these communities, and many of the participants came to The Belize Zoo to meet and greet, “Panama”, the official Belizean Harpy Eagle ambassador for his species “out there”.

The Education program has included the distribution of colour posters and brochures as well as the production of a short video about the program. The video, detailing the exciting aspects of BHERP, has been shown nationwide in Belize, and will continue to be shown on various television stations, throughout the year.


One of the male Harpy Eagles was found dead less than 2 km from LCRS. The cause of death, at this time, remains unknown. The bird will undergo a necropsy and a report on this will appear in a later update.

Given that mortality rate is expected to range about 60 percent in re-introduction programs, this event, while very sad, is also part of the reality of assuming an ambitious and complicated program such as the BHERP.

A great deal of collaboration and assistance is a continuing part of this important conservation work. Special thanks to:

Biologists monitoring Harpy Eagle activity since last Update:
- Kevin Hall
- Phillip Hannon
- Todd Gillen
- Chris Hatten

The Belize Defence Force, BDF
The Peregrine Fund
Education Department, TBZ
Birds Without Borders/Belize
The Ministry of Natural Resources, Government of Belize
Las Cuevas Research Station
Programme for Belize
Richard and Carol Foster, Cinematographers


Howell, S.N.G. and Webb, S. A guide to the birds of Mexico and northern Central America. 1995.

Touchton, J., Hsu, y and Palleroni, A. Foraging ecology of reintroduced captive-bred subadult harpy eagles (Harpia harpyja) on barro Colorado island, Panama. 2002.

Sharon Matola, Belize Country Coordinator
July 2004

Back to main Harpy Eagle introduction page

Update 2 of October 18, 2003

Update 3 of January 2004

Update 5 of December 2004


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