Though I've had a couple of late April Black-throated Blue Warbler sightings, the overwhelming majority are May birds. Below you'll find my BTBW records from the Pheasant Branch Creek Corridor in calendar form ― each iconified head representing a single observed bird. Here you can clearly see how they typically show up during the second week of May, which is usually when I'll take a week off from work so I can find one or two.
Because Wisconsin is positioned at the far northwest corner of their range for migration and breeding, I consider myself fortunate if I see just one or two BTBWs during the birding year. A few years back we had a banner year for them and chalked up 8 or 9 of them in one day at the creek corridor. Alas, I've occasionally missed them in spring, but found one or two in the fall. I don't think there's ever been a year that I've missed this species entirely since I began birding over 25 years ago.
I created this observation day calendar above only for this species probably because it's my favorite songbird, maybe even my favorite overall bird. I work every day this week, but I might be able to make it out to the creek corridor super early, or even after my shift. Still, if I miss it it's really no big deal. It's nice to see one's favorite species, but there is certainly no compelling need, as it's so often proclaimed in birding circles: "Oh, I need that!"
Right!?
Black-throated Blue images © 2021 Mike McDowell