Hindlimb Myology and Syndesmology of Haast's Eagle (Hieraaetus Moorei, Aves, Accipitridae) With Comparative and Functional Notes

Before human settlement, New Zealand's avian fauna comprised numerous large flightless birds along with aerial predators, including the formidable Haast's eagle (Hieraaetus moorei). This species vanished concurrently with other New Zealand megafauna, likely due to competition with humans for food resources. The hypothesis that ecological changes drove the extinction of Haast's eagle is grounded in assumptions about its foraging ecology, previously inferred from skeletal morphology. The present study enhances the understanding of the eagle's feeding behavior by reconstructing the muscles and ligaments of its hindlimbs. While structurally similar to other eagles, the hindlimbs of show adaptations for capturing and processing large prey. Notably, the femoral retractors and supinators were significantly enlarged, and the pronators mm. iliotrochanterici originated from a broader pelvic region compared to other species of Accipitridae. Enlarged tubercles on basal phalanges provided an attachment area for larger m. abductor digiti 2 and m. abductor digiti 4 muscles, enhancing the eagle's ability to handle large carcasses. These reconstructions corroborate prior assertions that Haast's eagle was highly adapted for hunting large prey, with its extinction to have likely resulted from an inability to adapt to diminishing megafauna populations.