Indian Black Eagle Ictinaetus malayensis (Temminck, 1822): Observations on nesting biology in Mizoram, India

Abstract

This study was undertaken to investigate the nesting behaviour of Indian Black Eagle Ictinaetus malayensis (Temminck, 1822). Observation sheets were made following Bald Eagle Monitoring Guidelines prepared for United States Fish and Wildlife Service-2007 with few modifications made to fit the necessities. Concealment nets were used to hide the observer in the observation post and other safety precautions were followed all through the monitoring process. Nikon P900, D7200, D500 fitted with a 200-500 mm lens were used for photography and Nikon Aculon A211 (15x50) binocular for observing the nest. The nest was observed for 85 days starting from early morning (0530 hrs) to evening (1730 hrs) by the observers in three shifts. The present study observed that the breeding season of I. malayensis begins from mid-December (aerial display) to February with the breeding pair building their nest on the branches placed horizontal to the branch of large old trees 25 m above the ground. The nests were 1-1.5 m in diameter and are lined with green leafy twig every alternate day while incubating and after each feed post-hatching. A single egg was laid and incubated for 30-35 days, young eagle need additional 50-60 days to fledge. We also observed that the diet solely consisted of rodents, especially the Pallas’s Squirrel, Hoary-bellied Squirrel, snakes, lizards and rats. I. malayensis, a top predator in the evergreen montane forest of Mizoram, mainly feed on rodents, thus playing a very important role in controlling the rodent population, while no instance of village fowl killed by I. malayensis was not recorded either by the authors nor the villagers themselves. The breeding success rate may not be high as only one of the two nests observed was successful, therefore, conserving this majestic forest raptor is essential for maintaining a balance of the forest ecosystem in the hill state.