Breeding landscape and nest spacing of two coastal raptors (Accipitriformes: White-bellied Sea Eagle Haliaeetus leucogaster and Brahminy Kite Haliastur indus) in Peninsular Malaysia

Abstract

The White-bellied Sea Eagle Haliaeetus leucogaster (Gmelin JF, 1788) and Brahminy Kite Haliastur indus (Boddaert, 1783) are two resident coastal raptors from India through Australia. Data on the breeding landscape and nest spacing of these raptors in Southeast Asia are limited. In this study, field observations were conducted bimonthly from February 2012 to July 2013 on Penang Island and in Matang Mangrove Forest in Western Peninsular Malaysia. Nine types of landscape and 17 study areas were investigated, and habitat variables were analyzed using ArcGIS software. A total of 88 White-bellied Sea Eagle and 212 Brahminy Kite nests were located. Logistic regression analysis showed that the proportion (%) of forest land and urban areas was significantly different between study areas with and without nests (p < 0.05). By contrast, area size (ha), elevation (m above sea level), and distance to shore (m) had no significant differences (p > 0.05). The White-bellied Sea Eagle and Brahminy Kite preferred dipterocarp and mangrove forests, respectively. Nest spacing was analyzed for 75 White-bellied Sea Eagle nests (consisting of seven occupied and 68 unoccupied nests) in Penang National Park and 210 Brahminy Kite nests (consisting of 27 occupied and 183 unoccupied nests) in Matang Mangrove Forest. The average distance between the occupied nests of the White-bellied Sea Eagle was 663.6 (± 377.3 standard deviation, SD, n = 7) m, whereas that of the Brahminy Kite was 1489.4 (± 1134.5 SD, n = 27) m. The proportion of nest occupancy to all nests was 9.3% for the White-bellied Sea Eagle and 12.8% for the Brahminy Kite. Conservation of islands covered with dipterocarp and mangrove forests is essential to the survival of coastal raptors in Southeast Asia.