The Philippine Eagle (Pithecophaga jefferyi) is one of the largest and rarest raptors, endemic to the forests of the Philippines. Standing nearly one meter tall with a wingspan that can exceed two meters, this bird requires a substantial caloric intake to sustain its size and predatory lifestyle. Classified as Critically Endangered, the eagle occupies the apex predator niche, necessitating a large and diverse prey base.
Primary Prey: Specialized Forest Hunters
The diet of the Philippine Eagle relies on large, arboreal mammals, which provide the necessary biomass. The most important single food source, particularly on Mindanao, is the Philippine Flying Lemur (Cynocephalus volans). In some documented areas, this gliding mammal can constitute up to 90% of the eagle’s diet, reflecting its high local availability and ease of capture.
Primates and civets also serve as primary targets, including Philippine long-tailed macaques and various palm civet species. These medium-sized prey items are caught directly from the forest canopy, ensuring the eagle receives a high-energy meal. However, the specific primary prey can vary significantly between islands due to faunal differences.
On Luzon, where the Philippine Flying Lemur is absent, the Northern Luzon giant cloud rat (Phloeomys pallidus) becomes a major food item. This rat weighs up to 2.5 kilograms, sometimes twice the weight of a flying lemur, highlighting the eagle’s reliance on the largest available arboreal mammals.
Secondary and Opportunistic Food Sources
While large mammals form the bulk of the diet, the Philippine Eagle is an opportunistic hunter with a varied menu that includes smaller and less common prey. This dietary flexibility is important for supplementing the main food source or surviving when primary prey populations are scarce. Secondary prey often includes other birds, such as large forest-dwelling species like hornbills and owls, which the eagle can snatch from the air or from perches.
Reptiles, including large snakes like pythons and monitor lizards, are also taken, showcasing the eagle’s strength in subduing formidable opponents. Supplemental mammals include tree squirrels, flying squirrels, and various species of bats, including large flying foxes. Prey specimens recovered from nests demonstrate an extreme size range, from small bats weighing just 10 grams up to juvenile Philippine deer weighing 14 kilograms.
The composition of this secondary diet is strongly influenced by the specific island and local habitat, with eagles adapting to whatever is most abundant. This adaptability is a survival trait, allowing the eagle to maintain its caloric intake across different forest types and elevations.
Hunting Techniques and Habitat Influence
The Philippine Eagle employs unique hunting strategies suited to the dense tropical canopy. The most commonly observed method is “still-hunting,” where the eagle perches motionless on a high branch, patiently scanning the forest below for any movement. This stealthy approach allows the eagle to conserve energy while maintaining a commanding view of its territory.
“Perch-hunting” involves the eagle making short, successive glides from one vantage point to another, often spiraling down a hillside. This method allows the raptor to cover a large area efficiently, searching for prey without expending the energy required for sustained flight. When a target is spotted, the eagle executes a fast, silent dive through the foliage to capture its prey with powerful talons.
Some breeding pairs may engage in cooperative “pair hunting,” where one eagle acts as a decoy to distract a group of monkeys or other animals. While the prey is focused on the distraction, the second eagle swoops in from an unexpected angle. This specialized hunting requires a large, undisturbed home range, with breeding pairs patrolling territories that can span over 100 square kilometers.