A bird that normally makes its home in California has made a rare and unexpected stopover in the Ottawa Valley, to the delight of amateur ornithologists from all over the province.

Birdwatchers have flocked to the area around an apple tree in Pakenham, just west of Ottawa, to catch a glimpse of Icterus bullockii, or Bullock's oriole.

With contrasting orange and black plumage, a black throat patch and a white wing bar, the bird resembles the better-known Baltimore oriole.

The Bullock's oriole's normal range is the American West Coast and southward to Mexico.

Ray Holland

Birdwatcher Ray Holland. (Stu Mills/CBC)

Ray Holland, an avid birdwatcher who lives in the Pakenham area, says he and Richard Waters, a birding friend, made the discovery on Saturday while they were out looking for another species.

"Quite by chance, sitting in a tree with a whole bunch of house sparrows, there was a bird that we had to look at each other twice," said Holland.

At first Holland believed the bird was a Baltimore oriole, which would also be unusual for the area, and he returned home satisfied with the sighting. But then, using his photographs and birding guides, he eventually determined the discovery was an even rarer female Bullock's oriole.

'It's absolutely fantastic. It's been mind-boggling.' - Ray Holland, birdwatcher

Not wanting to cause an unnecessary flap in the birdwatching community, Holland double-checked his guides before making an announcement online.

Since then, birders have been training their telephoto lenses on an apple tree — still laden with fruit — at the south end of Dalkeith Street, where the bird was first spotted.

"It's absolutely fantastic. It's been mind-boggling," says Holland, who estimates at least 130 people have come to see the bird. "For people around here, it's a super bird. It's a mega-bird for Ontario, an unexpected species."

Birdwatchers catch a rare glimpse of a Bullock's oriole in Packenham, Ont., on Dec. 1, 2015.0:44

Bird writer and columnist Bruce Di Labio was among those who visited Pakenham to see the oriole on Tuesday. He says this sighting is the first-ever confirmed in the Ottawa area, which birders consider to cover a 50-kilometre radius around Parliament Hill.

"I think now we're at 363 species in the Ottawa 50K. I've seen [Bullock's orioles] in my travels, but [this is the] first time in Ottawa. So we're all very pleased," Di Labio says.

Holland says another rare species, a Mountain bluebird, appeared in the area recently. He says Ottawa-area birders suspect a strong west-to-east jet stream through the month of November may be blowing the birds off their normal course.

Dec. 1 marks the beginning of birdwatchers' winter checklist season. That means birders keen to add the Bullock's oriole to their seasonal tallies are likely to continue descending on Pakenham to try catch a glimpse of the rare visitor.

"I just hope everybody gets to see it who came, because some of them come from a lot of miles away," says Holland.

Birdwatcher Ray Holland describes the moment he and a friend realized they'd made a rare find.0:49