The Guam Kingfisher: Reason For Hope
The Guam Kingfisher (Todiramphus cinnamominus), a native of the island of Guam, is now extinct in the wild.
It exists only in breeding programs in U.S. zoos and aquariums, and one on Guam. But there is reason to hope for these beautiful birds.
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Extinct in the Wild
Native to the island of Guam, the Guam Kingfisher (Todiramphus cinnamominus) is now extinct in the wild.
It exists only in a breeding program in some U.S. zoos and aquariums and one on Guam.
These brilliantly-colored birds are members of the tree kingfishers family. The Guam Kingfisher, called the Sihek in Chamorro in the native language of Guam, is one of three species of Micronesian Kingfishers.
The other two species occur on the islands of Pohnpei where the birds seem to be thriving, and Palau, where the population is declining. The kingfishers in these three different geographic locations were considered to be subspecies until 2015 when the taxonomy was changed and each was named a separate species.
Image by Robin Riggs
At the Aquarium of the Pacific
The Aquarium of the Pacific is one of twenty-three U.S. aquariums and zoos that are participating in a breeding program to preserve this species. Due to our favorable southern California climate, we are able to house our pair of kingfishers outdoors year-round, and that may be an asset for a successful breeding program.
A Cultural Origin Story
Chamorro stories tell of a village woman who was always talking loudly and making trouble.
She wore an orange kerchief and a blue dress with a white apron. An angry “taotaomo’na” (spirit of Chamorro ancestors) then turned the woman into the first Sihek.
Her clothing became the colors of the female Sihek. Now, the unhappy bird calls loudly when people are near.
Although once found in almost all habitats on Guam except for pure savanna or wetlands, this species was primarily a closed-canopy forest bird, preferring woodlands and limestone forests.
They preferred perches on a low, exposed branch where they could watch for potential prey. They also inhabited ravines, agricultural fields, and secondary forests in addition to edges of forests and openings spaces. Mature forests with standing dead trees for nesting, exposed perches, and a variety of prey were also important.
Illustration credit: USGS (United States Geological Service)
Adult Guam Kingfishers are sexually dimorphic, that is, males and females differ in appearance and size.
Physical Characteristics (Cont.)
Both sexes have large heads, dark brown feet and irises, large black bills with some white at the base of the lower mandible, and greenish-blue backs.
Males have a black ring around the eyes, a black line around the nape of the neck, a cinnamon-brown head, neck, and upper back and underparts. The lower back, lesser underwing coverts, and shoulder feathers of males are greenish-blue. They have a blue tail.
Females are similar to the male but with a paler upper breast, throat, and chin, and white underparts and wing linings.
Size, Weight and Diet
Size and Weight
These birds measure around 9 inches. Males weigh 50.5 to 63.8 grams (1.8 to 2.6 ounces), and females weigh 58.0 to 76.0 grams (2.0 to 2.7 ounces).
In the wild these kingfishers ate a carnivorous diet of large terrestrial insects and small vertebrates including grasshoppers, cicadas, skinks, anoles, worms, and hermit crabs. They would sit motionless on tree branches then swoop down to capture prey off the ground or off nearby foliage. They sometimes hunted insects in tree bark. These kingfishers beat their prey against a hard surface before swallowing it whole. At the Aquarium they are fed rickets, anoles, geckos and mice.
Both sexes become sexually mature at about two years of age.
Females start to engage in flirtatious courtships. If the courtship is successful, a life-long partnership is usually established; however, some mated pairs “divorce” each other even years later.
The pair usually nests in natural tree cavities or build their own nest in large, soft, dead trees, termite nests in trees, or in root masses of tree ferns. Nests are made about a month before egg-laying occurs. The male and female work together to build the nest by using their bills to excavate cavities into trees and rotting wood.
Several nests may be built although only one will be used.
It has been suggested that this activity may help the pair to bond.
It has also been suggested that the parental behavior may be enhanced by a non-breeding escort bird that helps with breeding and guarding the nest and territory.
The breeding season starts in December and several clutches may be laid. Clutch size is usually two but the range is one to three eggs. The eggs are incubated by both parents for about twenty-two days. Nestlings are fed by both parents. Fledging occurs when the chicks are about thirty days old.
Guam Kingfishers may form large flocks of territorial birds.
They exhibit socially complex behaviors including aggression towards birds of other species, their own species, and especially between bonded pairs. They may even fail to bond with a member of the opposite sex.
Their loud, raspy voices are usually heard when they awaken at dawn with such regularity that they served as an alarm clock for nearby humans.
Adaptation and Longevity
These kingfishers make a number of different vocalizations, ranging from loud rattle-like calls that can be heard for several hundred meters (useful in dense forests) to soft scratchy calls made when the birds are in close proximity to one another. While in flight thy give a loud rattle-call, while a shorter version is used when diving for food, when excavating nests and during aggressive interactions. Begging nestlings also produce a type of rattle-call.
Now listed as endangered under the federal Endangered Species Act and critically endangered internationally, prior to World War II the Guam Kingfishers existed in large numbers almost all over Guam.
The rapid decline is attributed to destruction of natural habitats and encroachment by humans for housing, agriculture fields, and the military airstrip; ingestion of prey and food items contaminated with DDT and malathion; and introduced predator species such as rats, cats, monitor lizards and especially the brown tree snake. The snakes are largely responsible for the near extinction of this subspecies in the wild.
Brown Tree Snake
Brown tree snakes are believed to have arrived on Guam in ships that may have come from Australia, Papua New Guinea, Vietnam or Melanesia. The snakes devoured eggs, hunted defenseless individual birds, and decimated the population.
By 1984 only 29 wild birds remained. In an effort to save them from extinction of the Guam Department of Aquatic and Wildlife Resources and U.S. Fish and Wildlife captured all of these remaining birds. These birds became the nucleus of today’s breeding program on Guam and in U.S. zoos and aquariums.
Reason For Hope
The zoo and aquarium programs operate under an American Association of Zoos and Aquariums (AZA) Species Survival Plan For the Guam Kingfisher.
In 2014 there were 139 birds in the breeding program. While it may be possible to increase the number of Guam Kingfishers to a level where they can be removed from the Endangered Species list, it is doubtful that it will possible to reintroduce them to Guam, because of the difficulty in eradicating the brown tree snake.
Researchers believe they may have to be introduced to Pohnpei or Rota where a Micronesian Kingfisher subspecies appears to be thriving.