John went to Newfoundland with Z Tours to see the Yellow-legged Gull. Because they never saw it, they spent most of their time looking for it. They did see nine other gull species. The group list was Black-headed Gull, Bonaparte's Gull, Common/Mew Gull, Ring-billed Gull, Herring Gull, Iceland/Thayer's Gull, Lesser Black-backed Gull, Glaucous Gull and Great Black-backed Gull. John will have to decide if he will look for and list the west coast versions of those two two-named gulls.
So the way this works is, you find a likely pond filled to the brim with gulls and start scanning for the Yellow-legged one. It is rumored to hang out at the town dump which is closed to birders, drat. Then, when it feels like it, it visits one of the nearby ponds to bathe along with hundreds of other gulls. This gull is common in the Mediterranean and the ones that end up in Newfoundland seem to originate in the Azores and a few visit every winter. John is already considering another visit in late fall when they show up again.
Some of the other birds John saw would be difficult to get later and in other places, so he was happy to see the Purple Sandpiper, the Tufted Duck, the Black-headed Gull, the Lesser Black-backed Gull and the cute little Dovekie.
He now has about 180 species with 11 being code 3 or higher. For those who aren't hardcore birders, code 1 and 2 are birds you can usually see without risking life and limb, 3, 4 and 5 are a BIT more difficult and, I understand, code 6 is essentially extinct.