10. Pacific Golden Plover – Records for Newfoundland (3), Quebec, New Jersey etc. This is a really difficult species to tell from American Golden Plover. The hardest thing in finding this species in Ontario will be getting good enough looks (or documentation), to note the ID features.
9. Yellow-legged Gull – gulls are tough to ID, but easier once you learn the features. Adults are much easier for this species (from Nov-Feb only).
8. Allen’s Hummingbird – several hummingbirds would be new for the provincial list, but this one needs an in-the-hand ID, so it makes the "hard to ID" list.
7. Red-naped Sapsucker – I don’t really like species like this.. Split from “Yellow-belled”, would be very difficult to confirm in Ontario. A hybrid was found at Long Point (Mike Burrell (et al?)) in 2010.
6. Hammond’s Flycatcher – “overdue”, but these empidonax are tough to deal with! Its sister species (Dusky) was caught in a mist net for the first and only record. New york had one or two recenty
5. “Western" Flycatcher – Two species here – if and when it shows up in the fall, it will get the “western” label since they’re virtually the same on looks alone. (Pacific slope and Cordilliean)
4. Cassin’s Vireo – similar to the sapsuckers, a “virtually impossible to confirm” sister species to Blue-headed. They probably aren't even a species ;)
Cassin's Vireo proof- Pelee
3. Clark’s Grebe- One of these rare “Western Grebes” reported in Ontario will one day be the sister-species: Clark’s Grebe. Watch for that brighter yellow bill!
2. MacGillivary’s Warbler – hard to find, adults much easier to ID than any possible fall records. Mourning Warbler’s with thin eye arcs are out there to confuse you.
1. Glaucous-winged Gull – hybrids make this ID tough, some ages would be easier than others – but not too hard. My vote for “most overdue” species for Ontario as well.