What a day! Yesterday morning, I read a posting on the local provincial discussion group regarding the discovery of a mega-rarity: a Slaty-backed Gull, native to NE Asia, seen very occasionally off the coast of Alaska and only rarely anywhere else in North America. There's only a single recorded occurrence in my province of Manitoba. I gulped my coffee, quickly loaded binoculars, spotting scope, tripod, snacks and other essentials into my truck, made a half-hearted and thankfully-rejected offer to my wife to accompany me, and then I was off!
Landfill sites are Meccas for gull-watchers, and this is a big one. All I knew as Google Maps guided me to the location was that the bird had been seen in a large field apparently right across from the entrance to the landfill site. When I arrived at roughly 8am, I was treated to the imposing sight of a large plowed field littered with something like 10,000 gulls of various species. I'm not pulling that number out of an arbitrarily chosen orifice; an important skill to develop as a birder is the ability to estimate large-numbered congregations by a method known as "blocking", whereby you count 10 or 20 or 100 birds, see how that sub-unit looks, and then estimate the appearance of 10x that number, then 10x that number, and so on. I've been doing this for close to a half-century and my estimates are usually very close to those of other experienced bird-counters.
And so began my descent into the personal hell of yesterday. I began at one end of the field and quickly began scanning through, looking for the unique large size and dark-coloured mantle of the Slaty-backed and several other similar species that would be fairly distinctive in the crowd. Each time a candidate was found, it required extended and minute examination; I needed to see the bill colour, leg colour, and the pattern of white spots at the tips of the spread wings to be sure I was looking at the legendary Slaty-back as opposed to the less-rare but still uncommon Western, Lesser Black-backed and Greater Black-backed. Not as difficult as it sounds; 99+% of the assemblage consisted of Ring-billed and Herring Gulls, and the potential dark-mantled birds mentioned above were very few and far between...but there were soooo many birds to sort through...
As I continued, I met and spoke to a number of other idiots engaged in a similar pursuit, but I was the only one who had driven 150km to get there; the rest of them were all locals, with all the time in the world. Some of these folks told me of the locations of several more fields scattered around the periphery of the giant landfill site, and so after working my way through a field I would quickly drive to the next one and start over. The combined total of birds on the ground was probably about twice the 10,000 of my initial estimate in the first field. Most didn't need to be looked at for long...but they all needed to be at least seen...
This continued on throughout the day. I completed the loop that took me to all four major fields, then began again at the beginning. All the while, birds were constantly trading into and out of the landfill site itself, inaccessible to be seen, so the total number of birds present far exceeded the number that could be visible at any given moment. An adult Bald Eagle amused himself by periodically doing a flyover of a field, flushing thousand of birds into the air only to land again a few minutes later...forcing me to start from scratch to cover the whole field.
It was fatiguing, to say the least. The weather at least was gorgeous; sunny, windless, above freezing temperatures, a pleasure to be outside. I spent the day drinking coffee, munching on chocolate bars and trail mix and sandwiches, periodically finding secluded patches of brush in which to pee.
I found some terrific birds. I had three sightings of Lesser Black-backed Gull, which might or might not have been the same individual; each of these required an extended period of very careful observation. I even had a fantastic and up-close (less than 100 yards) encounter with a Black-headed Gull, by far the best view I have ever had of this very uncommon bird...but both of those species have been on my list for many years. There's no way I would have driven all that way for anything less than an actual lifer...
...and I never saw it. At around 6pm, the work within the landfill came to a halt, the heavy machinery shut down, the workers went home...and most of the thousands of gulls around its periphery which I had been staring at all day began to move into the site itself, out of reach and out of view, where they joined the likely thousands that had been in there all day long. I was forced to admit defeat. My eyes felt like sandpaper, I was tired and cranky and I still had almost an hour and a half of driving to get home. I had spent the entire day either sitting in my truck, or at most standing beside it, peering through a scope at birds 100 yards, 200 yards or even further away. The fatigue of maintaining concentration was pretty intense.
Gulls are known to sometimes stick around locations like this for many days, weeks, even months, unlike many other species of vagrant birds which are generally one-day wonders. My lifer Heermann's Gull was spotted at a location in Ontario where it was known for several years, returning each summer. I'll be watching the discussion boards for further sightings and more detail regarding the Slaty-back; I'm already planning a possible return trip tomorrow.
They do fly, but mostly walk around the place. They think they own my mum and dad’s yard and will hiss at you like a death adder if you get too close. Any threat though and they scurry off like the whimps that they truly are. All talk and no action mate 
