Abstract
We studied the breeding behavior of the Eastern Marsh Harrier Circus spilonotus in Hotoke Marsh, Aomori Prefecture, northern Japan from June to July in 2009. We focused on a nest containing two male nestlings and recorded their behaviors and food items by a video camera. The nestlings began to flutter at about 30 days of age and flew a short distance from the nest at about 39 days of age. They spent more than half of their time out of their nest at this period. They received foods from their parents in the air at about 45 days of age. At about 48 days of age they ceased to return to the nest. The video showed that the nestling diet consisted of small mammals (46%), birds (24%), frogs (12%) and unidentified prey items (18%). In addition, we analyzed the contents of 25 pellets, which showed that they included small mammals (70%), birds (27.5%) and insects (2.5%).
