Direct Observation of Two Chicks and Their Fledging in a Nest of the Japanese Golden Eagle (<i>Aquila chrysaetos japonica</i>)

The Golden Eagle Aquila chrysaetos is a raptor that inhabits mountainous areas. In Japan, the subspecies A. c. japonica is distributed throughout the country, mainly in Honshu. The population of Golden Eagles has been greatly reduced due to lack of food as well as reduction of hunting grounds. Furthermore, their reproductive rate is low. Most Golden Eagles in Japan lay two eggs per clutch; however, the number of chicks that fledge is almost always only one. Instances of two chicks fledging from the same nest are extremely rare, occurring in only 0.8% of successful breeding attempts. In June 2024, the author observed two chicks in a nest, and later confirmed the moment each chick departed the nest. The first chick left the nest at 16:51 on June 4th, and the second chick at 5:58 on June 8th. In addition, the two juvenile birds were observed flying every day during a juvenile bird field observation conducted from June 11th to June 15th. This is the first documented case in Japan where the moment two chicks fledged from the same nest was visually observed and recorded.