None of the dozen or so males we have captured around or near MacLaren Pond have ever ended up being Enallagma vernale, so I feel pretty safe in calling this one simply by seeing the shape of its cerci, distinguishing it from the also similar Boreal Bluet. But one can never be 100% with these. It is interesting that Boreal (Enallagma boreale) and Northern (Enallagma annexum) are rarely found at the same locale. I found Boreal at home over the weekend and Northern here.