Guam Micronesian Kingfisher

Halcyon cinnamomina cinnamomina

Description

The Halcyon cinnamomina cinnamomina (Guam micronesian kingfisher) is sexually dimorphic with males having head, neck, upper back and entire undersurface a rusty brown. Auriculars are black with bluish wash with a narrow black line extending around nape. It has a black orbital ring and the lower back, lesser wing-coverts and scapular are greenish blue. The outer webs of the wing feathers and tail are blue. The rump resembles the tail but is slightly lighter. Under-wing coverts are greenish-blue with dark brown feet, a black bill (base of mandible paler), and a dark brown iris. Adult females resemble adult males, but their chin and throat are white. There are a few cinnamon-tipped feathers on tibia and at the head of wing. The back and scapulars are dark olive-green and less blue. Immature specimens resemble adults, but have a brown crown mixed with greenish-blue and back and wing coverts are edged with pale cinnamon. The chin and throat are whitish, underparts are red, buffy-white in males and paler in females. Breast feathers and nape have dark edges. The indigenous people of Guam, the Chamorros, call this bird the "Sihek." H. c. cinnamomina is a subspecies of the "Micronesian kingfisher," another common name.

Behavior

The species has been observed nesting in all months except August through November during the rainy season. Nesting activity appears concentrated from December to July. An average clutch consists of two eggs. Both sexes participate in the excavation of the nest cavity in very soft rotten trees. Mated pairs have been reported "drilling" nest cavities primarily from January through July. However, nest cavity excavation has been observed during the entire year. Some cavities are apparently never used as nest cavities and may function primarily in the formation and maintenance of the pair bond and in courtship. Number of clutches per year is unknown, but observations during 1980-81 suggest some pairs produce two clutches per season. Both adults incubate eggs, brood, and feed young. Two clutches reported contained two eggs, while another nest was found with only one egg. Both sexes incubate the eggs during the day with the female only incubating at night. Both sexes brood and feed the altricial young and participate in feeding of the fledglings. The length of time of development of the young from hatching to independence is unknown. The Guam micronesian kingfisher does not migrate and apparently remains on territory all year round. Details of dispersal of young to new territories is unknown. The Guam micronesian kingfisher feeds entirely on animal matter including lizards, skinks, geckos, insects, annelids, and small crustaceans. It feeds mainly upon prey that is on the ground. In captivity, the species has taken geckos, anoles, newly born mice, crickets, wax moth larvae, and mealworms. The Guam micronesian kingfisher is a very deliberate forager, typically perching motionless on exposed perches in large trees that have good views of the ground below from which it swoops down to capture its prey, often calling. When successful, it returns to its perch, prey in its bill, and beats the prey side to side on the branch to stun it or kill it before swallowing it whole.

Habitat

The species nests and feeds primarily in mature limestone forest, mixed woodland, second growth stands, and to a lesser degree in the scrub forests of the northern plateau. It was also found in coastal strand vegetation containing coconut palm as well as riparian habitat. The Guam micronesian king-fisher is one of the few native birds that perches on powerlines or telephone poles adjacent to forest areas. The bird requires mature forest containing old rotting trees such as Pisonia grandis, Artocarpus mariannensis, and Cocos nucifera in which it builds its cavity nest. Experience in captive breeding the Guam micronesian kingfisher at several stateside zoos has demonstrated the importance of extremely rotten trees to serve as nest cavity sites for this species. P. grandis, usually the largest tree in the native forest, is preferred by the species when available. P. grandis, which has "soft wood," will survive for many years with rotten branches, broken off during typhoons, while the remainder of the tree is quite viable. These soft rotten branches serve as excellent nest cavity sites for the species.

Distribution

The Guam micronesian kingfisher is endemic to Guam, and was known historically to have occurred island-wide in all habitats except pure savanna and wetlands. By the 1970s, it had disappeared from southern Guam, but by 1978-79 was still found over much of northern Guam. A survey done by the U.S. Fish and Wildlife Service and the Guam Division of Aquatic and Wildlife Resources in 1981, estimated the total population to be 3,023. In 1985, the species on Guam was restricted to Northwest Field and the Conventional Weapons Storage Area with a population estimated to be less than 100 individuals. By January 1986, only a few individual males could be located in the wild. A captive breeding program began in 1983 by the Guam Division of Aquatic and Wildlife Resources in cooperation with the American Association of Zoological Parks and Aquariums at several of their mainland zoos. There are presently over 30 specimens in captivity.

Threats

Predation of eggs, young, and adults by the introduced nocturnal brown tree snake, Boiga irregularis, is thought to be responsible for the present decline of the Guam subspecies of micronesian kingfisher and other forest birds of Guam. Recently, introduced diseases were once suspected as possible causes for both the range reductions and extinctions noted for most native forest birds on Guam, but to date, no infectious organisms have been isolated on Guam that could account for the decline. Feral dogs, cats, and rats, which are found on Guam, are thought to be major factors in the decline of the Guam micronesian kingfisher. There have been major changes in Guam's vegetation before, during, and after the Second World War. However, substantial native habitat still remains on Guam and habitat degradation is not thought to be a major factor at present. If present development patterns continue to reduce and segment the dwindling available mature forest, recovery of the species may be hindered because of its apparent requirement of old rotting trees in mature forest in which to build its nest cavity. Pesticides may have been a factor for decline in the past, however an intensive pesticide survey conducted in 1981 on Guam, concluded that pesticides were not a significant factor at that time. While agonistic interactions between the Guam micronesian kingfisher and the black drongo, Dicrurus macrocerus, have been noted, competition was found to be an unlikely factor in the decline on Guam. In the past, hunting (as a food item) may have stressed the Guam micronesian kingfisher on Guam but there is no evidence to suggest that it was responsible for the species' recent decline on Guam.

Conservation and Recovery

The species is included in the Endangered Native Forest Birds (for Guam and Rota of the Mariana Islands) Recovery Plan. The recent, drastic decline of forest bird populations on Guam has been one of the most alarming and challenging endangered species problems of modern times. Current evidence points to an efficient predator of small birds, the brown tree snake, as the culprit. Once thought to be relatively resistant to snake predation, the Guam micronesian kingfisher's population on Guam has dwindled to just a few birds; in contrast, the collared kingfisher (H. chloris ) on Rota remains healthy. Only a few specimens are left in the wild on Guam, with almost all remaining individuals being solitary males. Presumably this is due to the nocturnal Boiga taking the incubating female individuals off the nest at night. It is likely that the Guam micronesian kingfisher will be extirpated from the wild on Guam in the near future, but its survival in captivity now appears assured with successful captive breeding of the species at three mainland U.S. zoos as a part of a captive breeding program set up by the Aquatic and Wildlife Resources Division, Guam Department of Agriculture and the American Association of Zoological Parks and Aquariums.

Contact

U. S. Fish and Wildlife Service
Regional Office, Division of Endangered Species
Eastside Federal Building
911 N. E. 11th Ave.
Portland, Oregon 97232-4181
Telephone: (503) 231-6121
http://pacific.fws.gov/

Reference

U. S. Fish and Wildlife Service. 18 January 2000. "Micronesian Kingfisher / Halcyon cinnamomina / Sihek." Threatened & Endangered Animals in the Pacific Islands. http://pacific.fws.gov/pacific/wesa/microkingfishindex.html