Knowledge on the breeding biology of Mountain hawk-eagle(Spizaetus nipalensis), an endangered raptor, has been lacking in Taiwan. From August 2006 to January 2007, study was conducted to record the species’ number by camera and to observe its courtship display at the same time along the Yanping Forest Service Road. In addition, feeding behaviors of two pairs of hawk-Eagles were recorded in April-May 2007.
Results showed courtship display began in December. One nest was located at Fenshan (750 m a.s.l.) and Jialuoban (400 m a.s.l.) on April 11th and 16th, respectively. Both nests were built on Grey-dorsal oaks (Cyclobalanopsis hypophaea), 17 and 23 m in height, respectively. Each nest had one nestling, estimated 51 and 43 days old, based on the appearance and nestling growth pattern of the Japanese race (S. n. orientalis). Estimated laying dates were on 7th and 21st January and hatching date on 21st February and 4th March, respectively. The two young left the nest on 5th and 9th May, 65 and 74 days after hatching, respectively.
In sequence, prey taken by the Jialuoban birds consisted of Formosan giant flying squirrels (SquirrelPetaurista petaurista) (12 individuals, 33.3%), and Red-bellied tree squirrels (Callosciurus erythraeus) (9, 25%), Swinhoe's japaluras (Japalura swinhonis) (4, 11.11%), White-faced flying squirrels (Petaurista alborufus lena) (2, 5.56%), Swinhoe's pheasants (Lophera swinhoii) (2, 5.56%), and a Formosan hill partridge (Arborophila crudigularis) (1, 2.78%), a Formosan rock-monkey (Macaca cyclopis) (1, 2.78%), a Formosan blue magpie (Urocissa caerulea) (1, 2.78%), and a Mountain scopes owl (Otus spilocephalus) (1, 2.78%) . While that of the Fenshan nest were Formosan giant flying squirrels (8, 28.57%), Red-bellied tree squirrels (7, 25%), White-faced flying squirrels (3, 10.7%), Swinhoe's pheasants (3, 10.7%), Formosan hill partridges (2, 7.14%), a Formosan ferret-badger (Melogale moschata subaurantiaca) (1, 13.5%) , a Swinhoe's japalura (1, 13.5%), a Brown hawk owl (Ninox scutulata) (1, 13.5%), and a Red bamboo snake (Elaphe poryphyracea) (1, 13.5%). In all, prey species taken by both nests consisted of four species of mammals, four species of birds, and two species of reptiles.
Number of feeding trips ranged ≤4 times a day for each nest. Feeding was made exclusively by the female. With respect to time of day, equal numbers of prey, 18, were brought to the nest in the morning and afternoon for Jialuoban young, while more prey were taken to the nest in the morning (20) than in the afternoon (8) for Fenshan. The number of Formosan giant flying squirrels delivered to the nest was four at 16:00 (Jialuoban) and three at 15:00 (Fenshan), that of the remaining hours was ≤2 individuals; overall, there were more squirrels brought to the nest in the morning, which was same for the Swinhoe's pheasant.
During the nestling period, five green nest materials, including grey-dorsal oak, Symplocos caudata, Mori cleyera (Cleyera japonica), beautiful nerve Eugenia (Syzygium euphlebium), and long-glans oak (Quercus longinux) were brought back to the nest exclusively by female. Most nest materials were delivered to the nest at 08:00-11:00.