Thursday, September 24, 2015

Land of the Lost: An Owl? In Hawai'i?

I opened this blog series on the birds of Hawai'i by discussing the nene, the Hawaiian goose species. The nene is descended from Canada Geese that ended up off course on their migrations south from Canada. It's not too surprising that they could survive the trip because the geese were strong fliers and could rest every so often. It is a great deal more surprising to see a native owl on the island. It's hard to imagine an owl surviving a journey of more than 2,000 miles over open ocean. But somewhere in fairly recent time it happened. A Short-eared Owl arrived. Accounts differ as to whether they were present when the Polynesians colonized the islands, but they were certainly present soon after. The Short-eared Owl is a common and widespread species across the planet, being found on every continent except Australia and Antarctica. The native owl in Hawai'i, the Pueo or Hawaiian Short-eared Owl, is considered a subspecies of the widespread Short-eared Owls (Asio flammeus sandwichensis). In other words, the birds have not accumulated enough evolutionary changes to be considered a separate species, although there are differences with their continental cousins. The owls are revered by the native Hawaiians, and numerous stories are told about them.
The photos above are the only clear shots I've taken of this fascinating and poorly-known bird. On a 2009 field trip with my students in Kauai, we were driving down the hill from Waimea Canyon (the "Grand Canyon of the Pacific"). I had been on the lookout for native birds all day, and had little success. As we drove by the lower end of the canyon, I was shocked to see an owl on a tree top just a short distance off the highway. I didn't know at the time that it was a rare opportunity, as they are not seen all that often, so much so that their numbers in the wild are unknown. They are considered endangered, though, because they nest on the ground and are subject to predation by mongooses, cats, dogs, and rats. They get hit by cars distressingly often, and they have been affected by the use of pesticides. Habitat loss is also a serious problem.

If you travel the islands, you may very well see another species of owl. The common Barn Owl was introduced to the islands in 1958 to help control the rodent population, especially in the sugar cane fields. As often happens in such situations, the owls made no quantifiable difference in the rat population, but instead developed a taste for some of the endangered native bird species. A controversial plan has been proposed to remove them from Hawai'i.

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