A Trio Of Rarities In The H.S.A.

The Hamilton Study Area is a circle with a radius of 25 miles (~40.2 km) that is centred on Dundurn Castle in Hamilton, Ontario. It is the official area of study for the Hamilton Naturalists Club, and many local birders keep an HSA list. For some, this is their most revered bird list. For me, it is a few rungs lower (following my World List, Canada List, Ontario List, World Photographed List, Ontario Photographed List, and a few others), but I always jump at the chance to add a new species to my HSA list. I grew up in south Cambridge, which is situated within the western boundary of the HSA. My formative years as a birder took place predominately in the HSA; not only in south Cambridge, but also in south Guelph where I attended university. In the years since, I have lived elsewhere, though the HSA has always been just a short drive away. 
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In recent weeks the HSA has produced several fantastic rare birds; the crown jewel being the Yellow-browed Warbler (Canada's 2nd ever record), but more on that bird in a minute. All told, I have added three species to my HSA list recently, bringing it up to 309. A good start. 

California Gull (foreground) - Brantford, Brant County

On April 22nd, Bill Lamond discovered a California Gull along the Grand River in Brantford (and safely within the HSA boundaries). Leave it to a Lamond to discover yet another rare bird in Brantford! As I had nothing planned, and California Gull is a species that I had yet to observe really well in Ontario, I jumped at the opportunity. The drive was relatively uneventful and the rain cleared just before I pulled up. Thirty seconds later and I was staring at beady eyed, yellow legged beast.

California Gull (middle) - Brantford, Brant County

The California Gull spent most of my visit resting on a muddy sandbar off one side of an island in the river, hanging out with Ring-billed and Herring Gulls mostly. The side-lighting was a bit harsh for photos, but with the aid of a scope the views were pretty excellent. Certainly much more satisfying than studying a distant bird half a mile away along the Niagara River. 

California Gull (foreground) - Brantford, Brant County

In the above image, the adult California Gull is in the foreground with an adult Herring Gull behind it. Adult California Gulls resemble our two common Larus gulls in southern Ontario (Herring and Ring-billed) but there are some obvious differences when viewed well. This individual is showing all of the classic field marks: 

-dark eye with bright red orbital ring
-bill has both red and black near the tip
-legs are a greenish yellow in colour, vs pinkish in Herring Gull and yellow in Ring-billed Gull
-overall size is intermediate between Herring (larger) and Ring-billed (smaller)
-differences in wingtip pattern, with a lot of black in the primaries
-mantle (back) colour is a shade darker than both Ring-billed and Herring Gulls
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California Gull - Brantford, Brant County

California Gulls are native to, you guessed it, California, but also the Great Plains and a number of other locations in western North America. In Ontario we see one or two reported each year, sometimes more and sometimes less. During my early years of birding, an individual returned each winter to the Niagara River. This spoiled us and created an illusion that California Gulls were more common here than they really were. Since 2014, however, there have only been three California Gulls reported in Ontario prior to this year's Brantford bird. That being said, I am sure that a lot more pass through our borders than what are reported, like all rarities. But with this species in particular, it can be a tricky identification (especially with immature plumages). 

California Gull - Brantford, Brant County

Not only was the California Gull a new HSA bird for me, it was also a species that I had never photographed before in Ontario. Following this photoshoot I have now photographed all but 14 bird species of the 398 bird species I have encountered in Ontario. Most of the remaining ones are rarities that I observed early in my birding career before I carried a camera. Some of the other missing species include Connecticut Warbler, Yellow Rail, King Rail and Barn Owl. Not many easy ones left!

California Gull - Brantford, Brant County

The California Gull remained in the area and was seen by a few lucky birders for a brief time the following day, but it has not been reported since. During spring migration birds move on quickly so one must not waste time if chasing a reported rarity at this time of year!

The next rarity that arrived in the HSA is a species that is on the short list of rarest birds to ever occur in Ontario. That's right, it is up there with recent finds like Yellow-nosed Albatross, Great Kiskadee, and Eurasian Dotterel, or older records like Siberian Rubythroat and Slender-billed Curlew (ok maybe not on par with that last species, which is one of the most ridiculous rarities from the Great Lakes area ever).

Great Kiskadee - Rondeau Provincial Park (Sept 8, 2018)

During the morning of April 24, Pat Hare photographed an unusual bird traveling with kinglets while she was birding her local patch in Mississauga. With the assistance of the Merlin Bird ID app, she identified it as a Yellow-browed Warbler and she promptly spread the word to the birding community. I was pretty floored when I saw her photos - it was clearly an old world warbler in the genus Phylloscopus and it should not be anywhere near North America. 

Yellow-browed Warbler - Mississauga, Peel Region

Long story short, Laura and I twitched the warbler later that day. After a tense few minutes of waiting, we were successful in watching the Yellow-browed Warbler forage with its kinglet friends along a brushy creekbed. There were a lot of happy birders around, though I should mention that everyone was masked and keeping their distance. I was happy to hear that the warbler was just barely within the HSA as well!

Yellow-browed Warbler - Mississauga, Peel Region

I won't go into the bird's identification in detail in this blog post, though I should mention that non-vocal Phylloscopus warbler identification is not for the faint of heart. The most likely confusing species is the Hume's Leaf-Warbler, but most experts whose opinions were sought seem to think that this one checks all the boxes for Yellow-browed Warbler.

Yellow-browed Warbler - Mississauga, Peel Region

The Yellow-browed Warbler breeds in the eastern Palearctic and winters in southeast Asia. It is a regular vagrant to Europe, especially in the autumn. A quick check of eBird shows a few records from islands in Alaska, as well as records from California, Baja California, Wisconsin and British Colombia. The British Colombia bird was from last autumn and furnished the first record for Canada.  Most North American reports of this species are from the autumn. It is reasonable to surmise that this Yellow-browed Warbler also arrived in North America in the autumn, spent the winter somewhere, and was migrating back north with its new kinglet friends when it was discovered. We will never know the truth but that seems like the most reasonable solution to me. ​

Yellow-browed Warbler - Mississauga, Peel Region

Prior to our arrival, some others had discovered this Big Brown Bat roosting near where the Yellow-browed Warbler was foraging. 

Big Brown Bat - Mississauga, Peel Region

The third (and final) rare bird that I want to highlight from this post is not a true provincial rarity, but it is a special species all the same. On April 28, Connor Bennett discovered a singing male Cerulean Warbler in the exact centre of the HSA (indeed, it was on the grounds of Dundurn Castle). Probably hundreds of birders observed the Cerulean during its four-day stay. If nothing else, that is a testament to how mainstream birding and bird photography has become during the pandemic.

Cerulean Warbler - Dundurn Castle, City of Hamilton

Cerulean Warbler populations have declined sharply in recent years, especially at the fringes of the species' range such as here in Ontario. While once a fairly common warbler of mature deciduous forests of southern Ontario, Ceruleans have vanished from some areas and are quite rare in others. Deforestation is probably the biggest threat since Cerulean Warblers require large tracts of deciduous forest. Deforestation on the wintering grounds has also done a number to Cerulean Warbler populations. Niagara Region, where I have lived for most of the past five years, used to have a thriving Cerulean Warbler population. The species is now likely extirpated from Niagara which is not a surprise when you see how little forest cover remains. Living in the deep south of Ontario can be pretty depressing at times. 

Cerulean Warbler - Dundurn Castle, City of Hamilton

The Cerulean Warbler was a lifer for Laura and we enjoyed excellent views as it busily fed while singing as often as it could. A crowd of photographers were busy snapping away so we only hung around for a few minutes and I did not take any photos that I am really happy with. With that one out of the way, we will have to find one of "our own" somewhere else this spring!