<p>Climate change poses major conservation challenges that necessitate greater knowledge of how species may adapt. Analysis of museum specimens can provide evidence of how species have adapted morphologically to climate change in the recent past. Given that the effects of climate change have been non-uniform across the globe, evaluating morphological change across different populations of the same species is an important, yet underutilized, framework for understanding species responses to climate change. We compared morphological change responses across three White-crowned Sparrow (<i>Zonotrichia leucophrys</i>) subspecies and the Golden-crowned Sparrow (<i>Z. atricapilla</i>) that all co-occur during winter in central California. We expected these taxa to show parallel patterns of temporal morphological change that recapitulate Allen’s (longer appendages) and Bergmann’s rules (decreasing body size) in response to warming trends over the past century. However, only the <i>Z. l. gambelii</i> subspecies exhibited change in the direction predicted by both rules with an increase in bill surface area and a decrease in wing length. Wing length in the Golden-crowned Sparrow also decreased over time in line with Bergmann’s rule. Temporal morphological change in the California resident subspecies (<i>Z. l. nuttalli</i>) was non-linear and tracked fluctuations in precipitation over the past century. Non-parallel change across taxa suggests that each subspecies likely experienced different climate change regimes within their breeding ranges and are not responding to effects of climate change in their shared wintering distribution. We hypothesize that faster warming rates at high latitudes may be driving the greater morphological change observed in the northern breeding subspecies. This study highlights the importance of intraspecific comparisons for deciphering organismal responses to human-induced ecological change.</p>