Deuterium, a stable isotope of hydrogen expressed as δD, has been recorded in precipitation around the world since the 1960’s and those 40-year averages are often used in the study of avian ecology. Deuterium varies geographically and temporally throughout the year due to temperature changes. This study hypothesized that deuterium may have also increased over time due to temperature increases caused by climate change. Deuterium was investigated in avian museum specimens from the last century in Tompkins County, New York. Specimens were chosen using two different criteria: one including a wide variety of species to investigate general trends and the other restricted to a few species to reduce noise in the data. Across a wide variety of passerine species, δD demonstrated an increasing trend over time, but the explanatory power of time was low (r2=0.1134). When analysis was restricted to a single species, this relationship disappeared. The relationship between temperature and δD rarely explained more than ten percent of the variation in the data. Statistically significant differences were found between species and between the sexes, suggesting the need for further research in these areas.