Check out his great photos from the area here: http://mustap.smugmug.com/Nature/Birding-in-Ontario/WaterlooDump/11045791_NVtdpr#!i=1707162570&k=H8wtnPn
We found our target bird, a spectacularly dark juvenile Thayer's Gull (one of 2) that Peeter had photographed in the area yesterday. We hung around for quite a while, but "record shots" were the best I could do:
Another highlight was a sweet adult Herring X Great Black-backed Gull Hybrid:
A very fun chance to get some gull photos, considering there was only a few hundred gulls present!