If you can encourage a threatened native species, help control non-native pests, benefit the state’s farmers and preserve a culturally important icon, you’ve hit an ecological grand slam.
That’s exactly what the University of Hawaii’s Melissa Price is trying to do with the islands’ pueo owls. The striking, dark birds are a species of short-eared, ground-dwelling owl.
“Pueo are the only native raptor that breeds on all the Hawaiian islands,” Price said. “Ospreys visit. Peregrine falcons visit. But as far as breeding here, it’s the short-eared owls.”
Beyond their important place in the island’s natural systems, pueo also have an important place in the island’s spiritual life. They are seen as a common form taken by ‘aumakua, or ancestor spirits.
Pueo are listed as threatened on Oahu but exact numbers are hard to come by. Getting a better idea of the population and distribution of pueo is one of the objectives of Price’s new grant with the Western Sustainable Agricultural Research and Education program, which builds on work supported by the State of Hawaii and the U.S. Navy.
“Owls are tricky,” she explained. “They only get active about 20 minutes before it’s completely dark, at least on Oahu. There are reports they may be more active during the day on other islands.”
In fact, the owls are so hard to count, some people told Price her team would be lucky to find any pueo at all. However, her team found a nest in Oahu’s wetlands in just two weeks, and made 11 sightings. Based on sightings and surveys, Price has documented the birds nest in wetlands, at higher elevations and in native forests under ferns.
“Our initial estimate is that there are probably around 800 pueo on Oahu, but that range could be 12 to 2,200,” she said. “You expect raptors to be at low densities, but how do you know with an apex predator at the top of the food pyramid what the numbers should be?”
Another objective of the research is to document what pueo eat by examining the pellets of undigested bones and fur owl regurgitate. The initial results there look encouraging.
“In the lowland areas, their diet contains a lot of non-native birds and most of those are pest species,” Price said. “Controlling avian pests is really expensive and difficult, so having a raptor targeting those birds is a nice solution for everyone.”
Hawaii also has barn owls, which were introduced to the island ecosystem in the 1950s, but barn owls prey on both native and non-native species, Price said.
Her research will document the seasonal use of agricultural lands by pueo, and develop recommendations for producers on how to conserve or create pueo habitat to get their pest-management benefits.
“A lot of people are interested in how pueo can be managed,” she said. “Hopefully we’ll be able to answer some of those questions and help our pueo do their job as raptors all around the state.”
(photo by Tom Kualii)