The endemic Bawean Serpent-eagle Spilornis baweanus: habitat use, abundance and conservation

Abstract

The Bawean Serpent-eagle Spilornis baweanus is endemic to the 190 km 2 island of Bawean in the Java Sea (Indonesia) where it is the only resident diurnal raptor. A 15 day study in 2002 revealed that the species is present in small numbers throughout the island. The eagle's abundance was assessed by an island-wide survey and by sampling 28 1 km 2 plots covering five habitat types. There was a strong positive correlation between abundance and contact time in plots. Compared with other habitat types, the number of, and contact time with, serpent-eagles was higher in tall forest. The species was not recorded in mangrove and coastal forest. There was no correlation between the eagle's abundance and the nearest distance to villages. Based on the distribution of forest and the abundance of adult pairs within these forests, the available habitat totals 92 km 2 , in which some 60-75 adult serpent-eagles remain. Semi-structured interviews with the islanders revealed that recreational hunting poses the largest threat to the survival of the Bawean Serpent-eagle, and that the increase in recreational hunting was a relatively recent phenomenon. The forest on Bawean, including that in two reserves, is poorly protected and illegal logging and burning are widespread. The low degree of habitat protection, the severe threat posed by hunting and the very small population size of the eagle qualify the species to be included in the IUCN Red List as Critically Endangered. In order to safeguard the Bawean Serpent-eagle hunting must be stopped immediately and the remaining habitat needs to be better protected. This is probably best achieved by a conservation body in which local and regional authorities and NGOs cooperate.

Ornithological observations from Maratua and Bawean Islands, Indonesia

“…Century (Oberholser, 1917;Hoogerwerf, 1966Hoogerwerf, , 1967. Since these surveys, however, little ornithological work has been carried out on the island, except for a 2002 study of owls and birds of prey by Nijman (2004Nijman ( , 2006. He added three new species of large predatory birds to the island's list, bringing the historical total to 55, but did not comment on the status of species in other families.…”

“…Based on interviews with residents, Nijman (2006) reported that pellet guns became common on the island in the late 1990s, and that bird hunting is common. Additionally, the island is relatively close to Java, where many species are in high demand as cage-birds (Eaton et al, 2015).…”

Raptor Sanctuary: a Collaboration Scheme for Raptor Conservation in Indonesia

“…The population of raptors is threatened by illegal trade, hunting, habitat destruction and the use of pesticide (Rodriguez-Estrella et al, 1998;van Balen et al, 2000;Nijman, 2006;Supriatna, 2012). According to BirdLife International (2015), major threats are the increase in human population, weak law enforcement, and low public awareness about raptors conservation.…”

“…Популяциям хищных птиц угрожает не-легальная торговля, браконьерство, раз-рушение естественных местообитаний и использование пестицидов (RodriguezEstrella et al, 1998;van Balen et al, 2000;Nijman, 2006;Supriatna, 2012). По данным BirdLife International (2015), основные угрозы хищным птицам исходят от уве-личения численности населения, слабой правоохранительной деятельности и низ-кого уровня осведомлённости обществен-ности об охране хищных птиц.…”

Population Density, Home Range, and Habitat Use of Crested Serpent-Eagles (Spilornis cheela hoya) in Southern Taiwan: Using Distance-Based Analysis and Compositional Analysis at Different Spatial Scales

“…Although the breeding behavior and habitat preferences of the Crested Serpent-Eagle have been documented for several subspecies across Asia, including those in China, India, Japan, and Taiwan (Morioka 1995, Ueta and Minton 1996, Lin et al 1998, van Balen 1998, Zhang 2000, Sano 2003, Chou et al 2004, Chou 2005, Lin 2005, Nijman 2007, little is known about population density, home-range size, and habitat preferences of the Formosan Crested Serpent-Eagle (but see Chou andShiu 2007, Chou et al 2012). Since this knowledge is important for animal ecology (Manly et al 1993, Conner et al 2003, population ecology (Newton 1979), and conservation (Bildstein et al 1998, Thiollay 1998a, Sergio et al 2008, we used observations and radio-tracking to estimate population density and home-range size and to investigate the habitat use of the Formosan Crested Serpent-Eagle.…”