Bird bills possess an important thermoregulatory function as they shed heat via environmental heat exchange. Previous studies have demonstrated that birds in warmer climates tend to have larger bills than those living in colder climates, as larger bills can radiate more heat. Because heat is released without water loss, this cooling method is especially advantageous in water-restricted habitats. Here, we examine the influence of climate on bill morphology in Toxostoma thrashers, a group of 10 North American species that vary in bill morphology and occupied climate niche, with several species inhabiting arid or semiarid climates. Past examinations of thrasher bill morphology have only considered foraging, leaving unanswered the role of climate in divergence within this group. We photographed 520 Toxostoma museum specimens encompassing all 10 species, and calculated bill measurements from the photos using a MATLAB computer program created specifically for this purpose. For each species, we calculated occupied climate niche using data from WorldClim describing temperature and precipitation means and extremes. We then used multiple linear regression to determine how climate influences bill morphology. Preliminary analyses do not suggest a significant relationship between bill morphology and climate variables. This potentially indicates that other factors, such as foraging behavior, have played a stronger role in shaping the bill morphology of this genus.