Golden White-eye

Like other white-eyes, the golden white-eye is diurnal. In contrast to the bridled white-eye, which forages in groups and is not territorial, the golden white-eye occurs in pairs or small family groups consisting of a breeding pair and fledged young. The golden white-eye is also territorial, and pairs will sing throughout the day in response to neighbouring pairs. Groups can become aggressive when they encounter one another. The golden white-eye is also aggressive towards the smaller bridled white-eye, chasing it away from food and perches and flying through flocks of them in order to disperse them. While it chases other forest passerines, it is less aggressive towards them, and in fact the rufous fantail seeks out the golden white-eye, foraging behind it to snatch insects flushed by the latter species. The golden white-eye is socially dominant over the bridled white-eyes and rufous fantails, but it is subordinate to the Micronesian myzomela and is chased by that species. It is also occasionally chased by the fantails if it approaches their nests too closely.

The golden white-eye is endemic to the Northern Mariana Islands in the western Pacific Ocean, where it currently occurs on the islands of Saipan and Aguijan. Within its range, it occupies a variety of habitats, both natural and man-made. It is common in native forests, particularly limestone forests, but also occurs in open shrubland and suburban areas. On Saipan, the only habitats it is absent from are the marshes around Lake Susupe and grassy savannas.

The range of the golden white-eye has contracted considerably since the arrival of humans in the Mariana Islands. Fossil bones of this species have been found on the nearby islands of Tinian and Rota, and it may once have occurred on Guam and other islands in the Marianas. At present the golden white-eye is very common, and in fact a 1996 study found that their densities on Saipan were among the highest recorded for any bird, up to 2,095 birds/km² (8.47 per acre). It was believed that Saipan cannot sustain a larger population of this white-eye than it already does. A 2009 study, which incorporated results from a 2007 survey, found that the species had declined between 1982 and 2007, in common with two other species on Saipan, the rufous fantail and the nightingale reed warbler. All three species are insectivorous and were theorised to have declined due to habitat loss. Nevertheless, the species remained relatively abundant, and the current world population is estimated at around 71,997 birds. The species is nonetheless evaluated as Endangered by the IUCN because the population is expected to undergo a rapid decline if the brown tree snake becomes established on Saipan. The primary threat to this species is the brown tree snake, a native of Australia, New Guinea and the Solomon Islands, which eliminated all 12 landbird species on nearby Guam after being accidentally introduced. The snake has not yet become established on Saipan, one of the two islands that compose the range of the golden white-eye, and which holds the largest population of the species. The isolation of Aguijan makes the introduction of brown tree snakes there unlikely, but the small population there is vulnerable as the island is only 718 ha (1774 acres) in size and a direct hit by a supertyphoon could wipe them out. Efforts are under way to breed the species in captivity and to prevent the snakes from being introduced and established on Saipan. Six zoos have recently received this species and breeding was expected to begin by 2011. Success came more quickly, and the first captive birds were bred in 2009 in the North Carolina Zoo. Birds from captive breeding will be introduced on new islands. In addition, 24 birds were translocated from Saipan to the island of Sarigan, a predator-free island reserve, in 2011 in the hope of establishing a breeding population.