show Abstracthide AbstractMorphological shifts concordant with contemporary climate change have now been documented in a wide variety of systems. Despite the widespread documentation of morphological shifts, it is far from resolved whether these changes are driven by genetic shifts or plasticity, as few studies documenting contemporary morphological shifts are able to explicitly test for adaptation. We combine morphological and whole genome sequencing data to ask whether changes in body size and shape over the past four decades are accompanied by genetic shifts in Hermit Thrush.