I typically get 20 to 50 Cassin's Finches at a time from late March into mid
May at my sunflower seed feeders in west Reno (Washoe County). I have yet
to see or hear even a single bird this spring, and I think the chances are
pretty slim that they'll suddenly show up. This spring surge has been going
on every year for at least eleven years, with smaller spring increases in
earlier years back to 1997. Thus, the absolute absence of any Cassin's
Finches spring is really unusual. A quick look at eBird records for
March-April in the lower elevations of the Reno and Carson-to-Gardnerville
areas shows far fewer birds in the lowlands this year than in past years.
My thought in the past was that the finches used lower elevations such as
western Reno as a staging (i.e., pigging out) ground before moving up into
the Sierra to breed. This winter, with warmer temperatures and very little
snowpack in the higher elevations, the breeding grounds might have been
"ready" much earlier, so they just skipped the Reno stopover or made their
stopover at slightly higher elevations before moving farther uphill. That's
just a guess, though.