Females Lead Population Collapse of the Endangered Hawaii Creeper

Only 22 to 28 percent of the remaining adult population of the endangered Hawai‘i creeper (Oreomystis mana) found in the southern portion of the Hakalau Forest National Wildlife Refuge is female, raising concerns about the birds’ ability to continue to propagate the species, according to new research published by University of Hawai‘i at Mānoa scientists Leonard Freed and Rebecca Cann.

Hawaiian Creeper

Hawaiian Creeper

“Nesting is an energetically expensive activity, and females can incur more risks under increasingly challenging conditions,” said Biology Professor Freed.

Both male and female Hawai‘i creepers are olive green and have a short, straight gray bill and black mask.  The birds are endemic to the Island of Hawai‘i.  Creeping up and down koa and ‘ōhi‘a tree trunks and along the underside of larger branches, they feed on insects living under loose bark.

From 2001 to 2007, Hawai‘i creeper population declined by 63 percent throughout a 3,400-hectare open forest area at Hakalau Refuge on the windward slope of Mauna Kea, according to trend analyses by Freed and Cann.  The scientists observed the male-biased sex ratio along the elevation gradient in a formerly high density section of the forest, including a closed forest area study site that is considered more pristine, and found that it was associated with the population decline in the refuge’s open forest areas.  Hakalau formerly had the best population of creepers on the island…

More Here: Hawaiian Creeper

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