Rat snakes are truly incredible predators.  They can climb just about anything!  Until 2018, I assumed that birds nesting on my 2nd story terrace (which has no external stairway access) were safe.  One evening a rat snake proved me VERY wrong.  Not only did he come up to the second floor terrace, he proceeded to climb another 12' up a column to attack a Finch nest where two nestlings slept.  (The snake returned several hours later and attacked a Carolina Wren nest on this same terrace.)

It appears to be quite common for snake attacks to occur at the peak of nestling maturity -- just before fledge.  I assume this is because nestlings' heat signature (which snakes sense) is larger.  And, of course, they are a much more worthy meal.  The pair of Finches in this video were perching on the edge of the platform all day before the mid-night attack.  If only they had taken the leap.

The one positive note is that the location of this platform made it impossible for the snake to quickly wrap himself around both nestlings.  Hence, one nestling fledged into the night.