A preliminary report on the development of young Indian Eagle Owl Bubo bengalensis (Franklin, 1831) in and around Puducherry, southern India

摘要

Morphometric, weight and photographic data on the growth patterns of young Bubo bengalensis was obtained in three areas in and around Puducherry. We continuously monitored and observed the growth patterns of nine chicks in total between 10 and 60 days after hatching. Among the morphometric variables, bill and wing chord length showed a mild yet steady increase throughout the observation period, while tarsus length displayed a steep increase till the 20th day, fluctuated till the 40th day and then increased marginally till the 60th day. Body mass showed a steady increase before reaching a plateau between 35 and 45 days, after which only a marginal increase was observed. Chicks were born with whitish natal down. The prejuvenile moult occurred around the 14th or 15th day. Full juvenile plumage was attained by the 35th day and persisted even after 60 days. Morphometric data showed a marked variability, and in this context, ageing of nestlings based on measurements alone may not be accurate and must be complemented with feather moult patterns.