Bird song wonders

Yesterday was a weather day in the midwest.  We woke up to snow....all day it snowed.  And cold.  That is not unusual. It is often snowy and cold in this region.  However the snow was impressive...almost 11 inches in one day.  And the cold has been oppressive overnight..real temp below zero.
But before it all got so bad, I took a walk in this winter "wonderland".  I could barely see where I was going, but I trudged through the snow drifts along the familiar path.  This is how it looked:

I marveled at the activity of the birds.  They flocked to our feeders in great numbers: chickadees, titmice, cardinals, juncos, woodpeckers, and more.

I wanted to get some exercise before hunkering down in the house, so I followed the familiar trail  through the woods.

Since the blowing snow made opening the eyes difficult, I found myself focusing on the sounds.  Many birds were chirping in the woods.  At the edge of the woods, near a ravine where my husband's CWD project is decaying slowly--AKA rotting deer heads---I heard a sound that should have been familiar.  I had seen and heard several red tailed hawks in this area since the dumping of the heads.  But this was a little off.  It sounded like a red tail, but then again it didn't.  As I approached I saw what had been making the noise---a blue jay.  How remarkable.  This bird has the ability to sound like other birds of the forest, a common trait of corvids (family: Corvidae).  This includes crows, magpies, and ravens, and they are considered by some to be the most intelligent birds.
Although I had read about this ability to mimic sounds, I had never had such a direct experience.  I wonder what caused this jay to call in this way today?  I wonder what the red tail thinks when it hears that sound?  I wonder what other species it can imitate?
As I left the area, the jay returned to the "normal" jay call.  I wonder if I will have this experience again?  I hope so!