There is no precise estimate of the Philippine eagle population in Luzon, Eastern Visayas, or Mindanao
A Philippine eagle named ‘Mangayon’ was killed by a gunshot wound in Davao de Oro in July 2024. The eagle was injured and died from severe blood loss and possible sepsis, despite efforts to treat it.
Mangayon is just one of the many fallen eagles gunned down for food or sports, now considered a major factor why, in 50 to 80 years, the world’s largest and rarest bird of prey, as well as the Philippine national bird, may become extinct.
Scientists concluded the species’ extinction to factors that continue to threaten their population in the wild.
Population viability analysis
In 2024, a Philippine eagle Population Viability Analysis (PVA) 2024 was released by the Department of Environment and Natural Resources-Biodiversity Management Bureau (DENR-BMB), International Union for Conservation of Nature Species Survival Commission (IUCN SSC) Conservation Planning Specialist Group (CPSG), and the Philippine Eagle Foundation (PEF).
The PVA is a statistical model that simulates a species population in the wild based on the best scientific information available, mimicking how the species behaves and how its population may be affected by different variables.
Sought for comment, Marigio Laririt, assistant director of the DEMR-BMB, said via email on October 22 that the findings of the PVA quantify the probability based on specific factors, and the same would help improve the chances of species survival in the wild.
‘For some time now, scientists and nonscientists alike have been talking about the possibility of extinction of the Philippine eagle. The findings of [PVA] quantify the probability based on specific factors. These should help all of us working toward saving the Philippine Eagle chart an even more science-based roadmap with added urgency,’ she said.
Action plan
Last month, the DENR-BMB, in collaboration with the IUCN-CPSG and Mandai Nature, conducted the ‘Philippine Eagle PVA and Revision of the Philippine Eagle Species Action Plan (Pesap) Workshop’ in Davao City.
It was a follow-through of the Philippine Eagle PVA in April 2024, which identified the threats to population stability and their impacts and severity.
Besides validating the previous 2024 PVA, the draft Pesap was refined by identifying conservation needs of the Philippine eagle sub-populations in Luzon, Samar, Leyte, and Mindanao.
Unknown population
There’s no precise estimate of the Philippine eagle population in the Philippines, except for the known fact that they exist in Luzon, the Eastern Visayas and Mindanao.
This is attributed to the fact that the species is highly elusive and lives in remote, rugged terrain that’s extremely difficult to survey, said IUCN-CPSG Single-species Conservation Planning Program Officer Simon Valle.
‘Despite the excellent work done over the years by the [PEF], the species is highly elusive and lives in remote, rugged terrain that’s extremely difficult to survey,’ Valle, a conservation ecologist and population biologist, told the BusinessMirror via email on October 18.
Nevertheless, he thanked Dr. Luke Sutton for his work, with the Peregrine Fund in collaboration with PEF.
‘We now have a good sense of how many breeding pairs each region could potentially support, based on available forest habitat and what is known about the eagle’s territorial behavior,’ he said.
Habitat loss, hunting
Valle explained that through an extensive collaborative process involving the DENR-BMB, the PEF, academic partners, and representatives of Indigenous peoples, a detailed assessment of the threats facing the Philippine eagle across its range was made, identifying the continued loss and degradation of its forest habitat as the biggest danger to the species, followed by intentional or accidental killings.
‘Many of these incidents involve sub-adult birds-individuals that are fully grown but not yet of breeding age. Our population modelling shows that losing these young eagles has a particularly serious impact on the species’ long-term survival,’ he said.
‘These birds often wander into areas with human activity while searching for their own territories, where they may encounter farms, snares, or hunters. In that sense, these threats are also closely linked to the shrinking habitat and limited space for dispersal,’ he added.
Valle said other pressures include forest fires, mining, harvest of non-timber forest products, and charcoal-making.
‘While these threats occur across all three main island populations, their intensity and nature vary depending on local conditions,’ he said.
Juvenile ‘delinquency’
Meanwhile, Valle said young eagles are most vulnerable to hunting. At this stage of life, they leave their parents’ territory in search of their own nesting sites, mates, and suitable breeding grounds.
‘When forest habitat is limited, these young eagles are more likely to stray into areas with farms or human settlements, where they can come into conflict with people. or fall victim to accidental or deliberate shooting,’ he explained.
Hence, he said, the most effective way to reduce these risks is to secure as much suitable habitat as possible for the species.
This means expanding and protecting forest areas to provide the eagles more space to establish territorial safely, reducing dangerous encounters with humans.
‘This should come hand-in-hand with a better understanding of the value of this amazing species by the people who are lucky enough to live with or in proximity to Philippine eagle territories,’ he said.
Mindanao: A Philippine eagle haven
While the Philippine eagle is present in all three major islands of the Philippines, there is more known or recorded pairs in Mindanao.
This is because perhaps of its favorable weather conditions, said Jayson Ibañez, director for Conservation and Research at the PEF.
‘While there’s no precise population estimate that would point to Mindanao as having the largest number of Philippine eagle, the absence of typhoons in most of the island might mean a stable and intact environment, thus, a higher ability of the habitat to accommodate more eagles,’ he said.
However, he said such a hypothesis still needs to be tested and studied. The PEF, based in Davao City, implements its various programs mostly in Mindanao.
Asked whether the conservation program in Mindanao could be replicated in Visayas and Luzon, Ibañez responded in the positive.
‘The same core activities of the conservation program can be replicated, assuming we have adequate financial and manpower resources. For example, the same level of effort in monitoring nesting pairs in Luzon and Samar is very important. Monitoring and studying nesting pairs means we can better understand numbers and threats,’ he said.
Rescue center in Luzon?
Ibañez said establishing a rescue and conservation breeding facility in Luzon would be very beneficial for the eagles, particularly in preserving the Luzon bloodlines via a pool of captive eagles representing distinct genetic lines of the lineage on the island.
He said conservation breeding that carefully pairs and interbreeds individuals result in genetically healthy offspring, just like what is being done in Mindanao.
‘It helps in the genetic vigor of the species. A rescue and rehab facility also ensures that injured or sick birds are given a second chance to live longer and contribute new offspring to the wild,’ Ibañez said.
‘The island-specific conservation breeding facility can also exchange and interbreed [Philippine eagle] individuals, which can further bolster the genetic diversity, and consequently resilience of the population,’ he pointed out.
Population transfer, translocation
However, as far as the PEF’s population transfer or translocation program is concerned, the eagles from Mindanao to Luzon or Visayas, such as the ones released in Leyte island recently, chances remain uncertain, he said.
The release of captive-bred eagles from Mindanao and the transfer of surplus young eagles from Luzon, Samar, and Mindanao (conservation translocation) are sound species reintroduction methods, based on international raptor conservation standards.
However, he said there are steps to follow to subscribe to the international protocol for species reintroduction set by the IUCN.
Such steps are clustered into three assessments in biological and technical feasibility to answer questions, such as: 1) Is there an adequate food/prey base? 2) Are there adequate nesting trees? 3) Does the forest pass the high quality test in terms of canopy structure, tree density, forest vertical strata? etc.
Moreover, there should always be social and logistical feasibility to ensure that the stakeholders support the release, and that local laws and policies are in place to support the program and protect the eagles.
More importantly, the threats to the eagles in identified release areas should be eradicated.
Way forward
‘Experimental releases of both captive-bred and translocated eagles in key sites that implement all of the IUCN assessments and test release protocols are the way forward. Such a test release is now being undertaken in Leyte. Similar test releases can be done in Southern Luzon in the near future,’ Ibañez said.
In Leyte, he said since 2004, a total of five Philippine eagles have been released-three males and two males.
At least 15 to 20 eagles in total should be released in Leyte to establish a self-sustaining population of six eagle pairs (12 adults).
‘After release methods are tested, refined, and the eagles’ range of responses to their new release environment is studied and understood, we will then begin systematic release programs in every vacant habitats in Leyte and Luzon. But this is certainly a cross-generational effort where interventions today must be continued by the next generation of conservationists, and the next, until eagle numbers have increased and have become stable,’ Ibañez explained.