Date of Graduation
Davis College of Agriculture, Natural Resources and Design
Petra B Wood
James T Anderson
Keith L Bildstein
Todd E Katzner
Brenden E McNeil
Movement ecology is an emerging paradigm important to conservation biology and to the protection of global biodiversity. I used two common, but poorly known Philippine birds of prey as study tools in understanding movement ecology. One species is the migratory grey-faced buzzard (Butastur indicus), a raptor that which visits the islands in large numbers in winter. The other is the resident Philippine serpent eagle (Spilornis holospilus) which lives there at relatively high population density year-round. I used migration data at two terrestrial hawkwatch sites to assess how weather correlates influenced the movement behaviors of grey-faced buzzards. The grey-faced buzzard was the second most common raptor migrant using the Philippines as part of their migration route. My models show that they are more likely observed, either initiating or completing over-water crossings, in headwinds. I also created spatial models to understand how grey-faced buzzards overcome movement barriers (i.e. ocean). Modeled buzzard routes across the Philippines were between 1,582 and 2,970 km, and all repeatedly crossed water. Some of the routes overlapped at long and unavoidable over-water crossings. My models suggest that the optimal strategy for these birds is to find the shortest route to an exit point with the greatest possible access to stopover habitats and fewest over-water crossings under wind resistance. Additionally, I used road survey data to determine habitat associations of Philippine serpent eagle abundance across central and eastern Mindanao. My model showed that detection probability for the Philippine serpent eagle is relatively low, and the probability of occupancy was highest in near-pristine forests, especially low elevation dipterocarp forests. My road surveys helped establish the beginning of the breeding season for the Philippine serpent eagle. They also provided initial information on wintering habitats for grey-faced buzzards. This work is cutting-edge ecology and also provided natural history information about species for which there is almost no existing knowledge.
Concepcion, Camille B., "Movement Ecology of Philippine Birds of Prey" (2017). Graduate Theses, Dissertations, and Problem Reports. 5385.