Wildlife experts yesterday spotted and photographed an osprey feeding on fish in the ocean off Pearl Harbor — a sighting that may solve the mystery of an eagle-like bird seen Friday killing a cattle egret at Iroquois Point, just north of the harbor.

"The bird at Pearl Harbor (Friday) was probably an osprey. We saw one today in the same area as the eagle report," said Eric VanderWerf, a U.S. Fish and Wildlife Service biologist.

Residents from both sides of the Ko'olau mountains during the past week have reported numerous sighting of a large raptor, sometimes along the shore, sometimes over mountains, sometimes over streams or next to ponds. The Advertiser has received reports from Kane'ohe, Kailua, Waimanalo, Wa'ahila Ridge, and the Pearl Harbor and Iroquois Point area.

"We observed the osprey catching a fish and then flying back into the entrance of Pearl Harbor. ... At this point, I'm leaning toward it being one bird, and it's an osprey," said Michael Walther, who operates O'ahu Nature Tours, and who spotted a large raptor in the Pearl Harbor area both Sunday and yesterday, and photographed them.

An earlier suggestion that the bird might be the white-tailed sea eagle that had been on Kaua'i for the last four months has not been confirmed. The Kaua'i eagle, which arrived on the island in December, perhaps from its Asian home domain, was last spotted Wednesday, said Brenda Zaun, biologist with the Kilauea Point National Wildlife Refuge.

But Zaun said osprey are not known to take birds as big as egrets, and they are not known for soaring over mountain areas.

"There are some things that don't match up. We may still have something else out there," she said. She said it is perfectly possible that there is both an osprey and another raptor — and even that there is both an osprey and the Kaua'i white-tailed eagle.

"It has been seen on the north, south, east and west coasts of Kaua'i now. O'ahu would be just a short jaunt for this large bird," she said.

Raptors are not common visitors to the Islands, but they do show up occasionally, and this year might be a banner year. There are now confirmed to be at least the Kaua'i white-tailed eagle, a peregrine falcon seen on Kaua'i in April, the Pearl Harbor osprey and a harrier in the Ka'anapali area of Maui. Maui resident Robbie Vorfeld said he has seen the Maui bird, which he said appears to be a northern harrier, in the west Maui area for some time.

Hawai'i's native raptors include the 'io or Hawaiian hawk, which is found only on the Big Island, and the pueo or Hawaiian short-eared owl. The introduced barn owl is also found statewide.

When out-of-state raptors appear, smaller ones often stay a few weeks or months, and then disappear again, perhaps flying back whence they came.

But the biggest birds, the eagles, tend to stay. There is fossil evidence that white-tailed eagles were found 3,000 years ago on O'ahu, Moloka'i and Maui. And when a golden eagle arrived on Kaua'i in the mid-1970s, it stayed until it was killed in an attack on a helicopter in the early 1980s.

Reach Jan TenBruggencate at jant@honoluluadvertiser.com.