The Yushan National Park is home to two of the largest raptors, the Mountain Hawk eagle (Nisaetus nipalensis) and the Black eagle (Ictinaetus malayensis). However, there has been limited exploration of the ecological behaviors. This study uses visual observation, satellite tracking, and camera traps to survey their life history, and the findings will eventually be published in a popular science book. Between 2019 and 2023, a total of 6 Mountain hawk eagle s and 1 Black eagle were ringed. In September 2019, a 4-year-old female eagle was ringed, with a Minimum convex polygon (MCP) ranging from 628 km² initially to a reduced and maintained 13 km² after 2023.In May 2020, a Black eagle fledgling was ringed at 62 days old, gradually exploring from September to October. Tracked for nearly 1.5 years, MCP extended to 7,438 km².In June 2020, six-year-old subadult female eagle s (female bird of Zhongzhiguan pair) were ringed. The female successfully breeds in May 2021, the fledging expanding the MCP to 782 km².In January 2022, five-year-old male eagle s (male bird of Zhongzhiguan pair) were ringed, MCP was 11.2 km². overlapping with their home range by 90%.
However, it lost contact after late April, but reappearing on the capture platform in March 2023.In March 2022, an adult male eagle was released near Kuhanuosin Mountain, living in close proximity to the Zhongzhiguan pair separated by the Southern Cross-Island Highway, The MCP was 23.6 km², but by 2023, it had reduced to approximately 6.8 km². Both Mountain hawk eagle s and Black eagle build nests in Taiwan white pine (Pinus morrisonicola Hayata). The Mountain hawk eagle incubation period lasts 49 days, with Formosan reeve's muntjac (Muntiacus reevesi) being the primary prey (n=9, 25%), mainly young (n=8). Birds (n=11, 30.6%) follow, with the Swinhoe's pheasant being the most common (11.1%). In terms of biomass, Formosan Reeve's muntjac contribute the most (54.5%), followed by two species of flying squirrels (16.36%). Among birds, the Swinhoe's pheasant has the highest contribution (13.3%).
In 2021, leave the nest after a 70-day nesting period, gradually leaving the parental home range by late October, with a maximum straight-line distance of 22 km. In 2022, the Mountain hawk eagle began breeding again on February, with the incubation starting 12 days later than the previous year. The nest was relocated 300 meters away to a steep slope, but on April 13 (50 days after laying eggs), incubation failed, as did that of the Black eagle in the same area. The rainfall during the incubation period in that year was three to four times higher than the same period in 2021, suggesting a possible link to breeding failure. In 2023, the Mountain hawk eagle breed again, laying eggs 17 days earlier and the breeding successful, the fledging fly away from the nest, currently remaining active within the parental activity range, this indicates that the incubation period may be related to the postpartum condition of the parents.
During the nesting period that year, a new record of a Formosan macaque (Macaca cyclopis) preying was documented. In terms of flight patterns, the soaring time and wing loading of Mountain hawk eagle and Black eagle shown significant negative correlation (Spearman’s rs= -0.83, p=0.01), with Black eagle having lower wing loading and larger wing areas, resulting in a soaring time about 4.5 times longer than Mountain hawk eagle.