Warbler Guy, when should I expect to begin seeing migrant-arriving Yellow-rumped Warblers?

Gus, in Wisconsin, you should expect this common wood-warbler (that nests in n. WI) to vary annually in its arrival time, given the vagaries of spring weather in the Midwest.

Generally, first migrants north of their winter range occur in the Upper Midwest by as early as late March, but greater pulses arrive beginning in early April and soon after.

At this time (often when few if any leaves are present on deciduous trees), the Myrtle subspecies of the Yellow-rumps (Setophaga cornonata coronata) may seem ubiquitous, as some birders' patience levels are tested when bird-after-bird is, AGAIN, deemed a Yellow-rumped sighting.

That's a typical scenario in WI BEFORE the initial warm, Gulf breezes occur from the south.

Then, almost like magic in the final week of April or in early May, the diverse parade of wood-warbler family members begin appearing ALONG with Yellow-rumped.

In summary:

Peak movements of Yellow-rumps in the northern US and southern Canada occur from late April through mid-May. Like many songbird species, male Yellow-rumps migrate earlier than females, averaging 4 to 7 days sooner in their arrival upon breeding grounds.

Keep in mind that some hardy Yellow-rumped Warbler individuals remain throughout the non-breeding season in the Upper Midwest, especially during warmer winters.