Land-use change over time alters community structure of ecosystems by transformation into agricultural, urban, or suburban landscapes. Current ecosystems thus differ across the rural-urban land-use gradient. Naturally occurring differences in carbon isotope ratios between C₃ and C₄ plants and variations in nitrogen isotopes, due to environmental factors, provide a mechanism to determine an animal’s diet choices. Animals are what they eat; therefore diet is integrated in the carbon and nitrogen stable isotopic (δ¹³C and δ¹⁵N) signatures of animal tissues. As landscapes shift from prairie or forest ecosystems to anthropogenically fertilized agricultural or urban ecosystems, animal tissues reflect variations in the isotopic composition of the different plant communities.

Results/Conclusions

I use the Chicago region in a pilot study to identify effects of land-use change on the isotopic composition of squirrel diets along the rural-urban gradient. Current patterns of isotopes in consumer species that differ in diet and that are present throughout the gradient can be extrapolated to archived museum collections sample over space and time within the same region. Results from this study reveal landscape patterns that determine variations in δ¹³C and δ¹⁵N signatures of species due to anthropogenically driven habitat transformations in the Chicago region.