Tuesday, 1 December 2015

Bullock's Oriole chase

On November 28 Ray Holland and Richard Waters discovered an oriole in the town of Pakenham, located in Lanark County and about 45 minutes west of Ottawa. After some photos were circulated, it became apparent that the bird was a first-year female Bullock's Oriole, a very rare species in Ontario. The bird was seen several times throughout the day on November 29 and news spread quickly.

Bullock's Orioles are found in western and central North America, while Baltimore Orioles are found in the eastern and central parts of the continent. Between 1983 and 1995, the birds that we now know as Baltimore Oriole and Bullock's Oriole were considered one species, named Northern Oriole. This was based primarily because of the wide "contact zone" where the two species hybridized together. However, subsequent studies revealed that the zone of hybridization was not growing and was smaller than previously known. Additionally, there were many individuals of the "pure" Baltimore and Bullock's types within the hybridization zone. For these reasons and others, Northern Oriole was split again into two species in 1995. As any evolutionary biologist (or naturalist, really) can tell you, species are not discreet entities; rather the species concept was designed by humans to try to fit into neat little boxes the ever-evolving diversity of the world. The constant processes of evolution based on natural selection allow "species" to become dissimilar genetically if a barrier of some sort is in place. Conversely, if a barrier is removed, the two species may hybridize more frequently and the resulting gene flow allows the two species to become more similar genetically.  While Baltimore Orioles and Bullock's Orioles look quite different they have a relatively recent common ancestor and are closer related to each other than to other oriole species, like for example Orchard Oriole.

But I digress. As a birder who likes keeping lists, the Bullock's Oriole in Pakenham was a very good bird to see, as it would be a new one for my "all important" Ontario list. While listing takes second place to studying and attempting to understand the natural world around me, there is something exciting about the thrill of the chase and to be able to see a high number of unusual species in Ontario. As there were only six previous accepted records of Bullock's Oriole in Ontario, this bird was a high priority for me!

Bullock's Oriole sightings (screenshot from ebird.org)

After tying up some loose ends with my work, I arranged to meet up with Ken Burrell on Sunday evening and after meeting him in Toronto I hopped in his car while he drove to his brother Mike's place in Sunbury, north of Kingston. After a brief 5.5 hours at Mike and Erica's place (thanks guys!), we were up by 5-ish to get ready for the day in the field. Mark Read and James Barber drove up from Kingston, while Barb Charlton arrived from Hamilton. The six of us piled into two vehicles and we rolled in to Pakenham by 7:45.

For the first several hours there was no sign of the bird but the number of birders slowly increased . The oriole had been seen in previous days feeding on several apple trees in the neighbourhood and adjacent railway line, but it was a relatively large area to search. We were all confident that the oriole was still in the area, however, and would show up as the temperatures warmed.

By mid-morning Ken, Barb and I decided to be the sacrificial birders and stop in at the local restaurant for some breakfast. Sure enough, not five minutes after sitting down Barb received a text from Steve Charbonneau that the bird was being seen along the railway tracks! Fortunately the friendly waitress put our orders on hold and allowed us to leave our hot beverages to chase the bird, with our promise that we would be back to pay for the meal! Ken was in the washroom at the time but he must have understood the memo really quickly when he arrived at the table to see no sight of Barb and I.

We raced to the tracks where about 20 birders were gathered. The oriole was out of sight for the moment, but Bob Cermak got on it not long after, allowing the rest of us to finally lay eyes on the beaut. The sighting was brief, perhaps only 60 seconds in duration, but it was enough to closely study the intricacies of the bird's plumage as she fed on apples. I wasn't able to photograph it, but Steve Charbonneau kindly passed on this image to share. His photo is a pretty good representation of what we saw in the field.

Bullock's Oriole - Pakenham, Ontario (photo by Steve Charbonneau)

The day was getting on, and while we all would have loved better looks and photo opportunities there were other places to check out!

A happy crew: (from left to right) Mark Read, Barb Charlton, Mike Burrell, Ken Burrell and James Barber

The six of us (Mike, Ken, Barb, James, Mark and I) headed towards the Richmond area where another rare songbird was being seen - a female Mountain Bluebird. Like the Bullock's Oriole, this was the first one of its species to show up in the Ottawa birding area. Well, we didn't see it, though it had been seen around 15 minutes before we arrived. A Sharp-shinned Hawk clutching a Mountain Bluebird-sized morsel was suspicious... The bird hasn't been seen since, so I think we did get a look of the bluebird after all, just not as it was living!

Barb and I made one final stop on the way home; this time in Whitby to chase another Mountain Bluebird. This one represented the first record for the Greater Toronto Area and it had been entertaining birders for several days. The short photo-period of late November gave us little time to find the bird in the dim conditions at 4:30 PM. Fortunately, it was right where it had been reported. As the sun and the temperature dropped quickly we watched the bird doing its thing, searching for whatever morsel it could find in the grassy habitat. I bumped my ISO on my camera up to 3200 to obtain a fast enough shutter speed.

Mountain Bluebird - Whitby, Ontario

Mountain Bluebird - Whitby, Ontario

Mountain Bluebird - Whitby, Ontario

It was a long day in the field but certainly a worthwhile one - it certainly beat any day in the office!

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