On the breeding habits of the Eastern Grey Heron in Sabaru Island, Mie Prefecture

Abstract

1. In May, 1967, a colony of the Eastern Grey Heron, Ardea cinerea was found in Sabaru Island, Owase City, Mie Prefecture. This paper deals with the breeding habits of Ardea cinerea, and is based on the results of field observations from 1967 to 1971. 2. The colony is on the coastal island measurs 400*200m, in Owase Bay, and the vegetation is the evergreen broad-leaved forest, mainly consists of Castanopsis sieboldii. 3. Breeding numbers are 300*350 pairs. 4. Breeding period is from February to early July, earlier than other herons. 5. Nests tend to built the near of crown, and most found as about 80% of the tree hights. The habitat segregation especially between Ardea cinerea and Nycticorax n., from the nesting sites and breeding season was observed. 6. Clutch size is 2*5, the average size 3.8. Eggs are alternately incubate by male and female. 7. Home range in the breeding season is the area of a radius of 5*10 km, of the colony, mainly along the coast. The home range tend to magnify with the progress of breeding season.