Which bird's song is explicitly mentioned as needing to be differentiated from the phoebe's raspy ``fee-bee!`` call?

Answer

The sweeter, whistled ``fee-bee`` of the Black-capped Chickadee.

The text cautions against confusing the phoebe's raspy, quick ``fee-bee!`` call with the sweeter, whistled ``fee-bee`` given by the Black-capped Chickadee.

Which bird's song is explicitly mentioned as needing to be differentiated from the phoebe's raspy ``fee-bee!`` call?
raritybirdPhoebe