A. Hi Lance,
"Bear in the Birches" was one of Harper's most popular earlier images, and although it hasn't increased in value as of late, it is still one of his more popular serigraphs. Issued in 1972, I would estimate that it is worth $700-900 in pristine condition.
Framed piece from this time period usually demand less, as preservation practices were often ignored by framers. Have a Certified Framer (CPF) examine to see if conservation materials were used in the framing package.
Please Contact me if you have any further questions.