By Mar-Vic Cagurangan
After being held in captivity for more than three decades, the Guam kingfisher, locally known as “sihek,” will finally return to the wild on May 4 as an experimental population on Palmyra Atoll.
“The introduction on Palmyra Atoll is outside sihek's historical range because its primary habitat within its native range on Guam has been indefinitely altered by the accidental introduction of the predatory brown tree snake ( Boiga irregularis) in the mid-twentieth century,” the U.S. Fish and Wildlife Service stated in the final rule posted on Federal Register on April 4.
While tools to manage brown tree snakes at a landscape level are being deployed, the wildlife service said a complete eradication of the bird-eating reptile will be a long shot.
“We anticipate significant declines in sihek population that threaten the species' viability before reintroduction to Guam could occur,” the USFWS said.
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The federal agency, however, stressed that the introduction of sihek to Palmyra Atoll, located 5,869 km from Guam, is not intended to be a permanent solution to support a self-sustaining population.
“Rather,” the final rule said, “it is intended to facilitate the gathering of information and analysis to optimize efforts for re-establishment of the species on Guam once brown tree snakes can be sufficiently controlled at a landscape scale.”
The sihek is a compact rusty-red bird with a long dark blue tail and short dark blue wings, a large charcoal grey bill and a black stripe through its eyes.
The last Guam kingfisher was spotted in the wild in 1988, while biologists brought the surviving 29 birds into captivity to rescue them from total extinction. Today, 152 sihek live in 25 facilities around the world.
“The introduction of sihek to Palmyra Atoll is also likely to help increase the global population of this extinct-in-the-wild species in advance of a reintroduction effort on Guam,” the USFWS said.
One of the Northern Line Islands (southeast of Kingman Reef and north of Kiribati, Palmytra Atoll is situated halfway between Hawaii and American Samoa. It is currently owned and managed by the Service, The Nature Conservancy, and the Cooper family.
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Palmyra Atoll is also part of the Pacific Remote Islands Marine National Monument, which was established in 2009 and is co-managed by the Service and the National Oceanic and Atmospheric Administration.
“The best available data indicate the introduction of sihek to Palmyra Atoll is biologically feasible and will promote the conservation of the species,” the wildlife service said.
A small number of sihek to be released into the wild is classified as “a nonessential experimental population.”
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“The nonessential experimental population status is appropriate for the introduced population because we have determined that it is not essential to the continued existence of the species in the wild,” the wildlife service said.
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According to the published procedure, late-stage nestlings will be flown to Palmyra Atoll where they will be held in release aviaries for up to one month.
Three sets of three flight aviaries will be established across Palmyra Atoll around the locations deemed most suitable for habitat. During this time, sihek will undergo acclimation and training to respond to supplementary feeding signals.
Aviaries will have an opening to allow the birds to come and go freely.
“While still being held in pre-release aviaries on Palmyra Atoll, we will provide natural prey items as much or as often as necessary so the sihek can learn to forage on multiple food sources,” the wildlife service said.
“We will monitor each sihek daily, immediately after release and throughout their first year of release,” the wildlife service said. “Once released, sihek will be exposed to conditions in the wild that the species has not encountered in more than 30 years.”
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