Comparative behavioral ecology of the White-Bellied Sea Eagle and Brahminy Kite (Aves: Accipitriformes) in Northwestern Malaysia

Behavioral events of two raptor species, the White-bellied Sea Eagle, Haliaeetus leucogaster Gmelin, 1788 and Brahminy Kite, Haliastur indus Boddaert, 1783 were studied once every two weeks in two locations in northwestern Malaysia, namely Balik Pulau and Kuala Sepetang, from September 2012 to September 2013. The average total number of behavioral events per hour was 45.9 (±40.3 SD), 117.0 (±131.7 SD), and 285.8 (±185.0 SD) for H. leucogaster at Balik Pulau, and H. indus at Balik Pulau and Kuala Sepetang, respectively. The total number of individuals of each species observed was significantly influenced by the time of day and weather (p<0.05). It was observed that the percentage of time spent for perching, flying, hunting and competition was significantly different between these two species and between two locations. The total number of behavioral events during observation dates was no different for the White-bellied Sea Eagle than that of the Brahminy Kite. Overall, the percentage of time that the birds spent perching, flying, hunting, social behavior and competition was different between species. The highest rate of successful predation was 94.6% for H. leucogaster while it was lower for H. indus at Balik Pulau (72.8%). The time of day was an effective factor for determining behaviors of H. leucogaster while it was not significant for H. indus. The effect of boat numbers and weather on behavior varied between species and locations. The state of the tide and the number of crows present did not have any significant effect on activities of these two species. Results of the comparison of the percentage of occurrence of five types of behavior between adults and juveniles showed that behaviors of perching, hunting and social behavior were different for H. leucogaster, behaviors of perching, flying and social interaction for H. indus at Balik Pulau and behaviors of perching, flying, hunting and social interaction for H. indus at Kuala Sepetang. However, they did not show different behavioral events of involving competition.