Over the last decade, the explosion of books related to birding has seen the formation of a subgenre focused on the GISS concept. GISS (typically pronounced jizz) is an acronym for General Impression, Size, and Shape. This refers to the method of identifying a bird by visible features other than the color and markings. It’s how most seasoned birders make split-second identifications in the field. Over time, GISS has come to be a catch-all term for the holistic approach to bird identification where distribution, time of year, habitat, and behavioral considerations blend with size and shape (and good old fashioned field marks!) to make a bird knowable in an instant.
