Serum biochemistry suggests a physiological response to environmental stress in a native urban Eastern Gray Squirrel (<i>Sciurus carolinensis</i>) population

Abstract

Urban wildlife populations experience human-driven environmental changes that can be both beneficial and detrimental to individual health. We measured body condition and serum chemistry (electrolyte levels, markers of kidney and liver function, protein, glucose, and cholesterol) in a native urban and rural population of Eastern Gray Squirrel (Sciurus carolinensis) to assess whether we could detect physiological responses to environmental stressors or dietary differences. We found no differences in body condition between habitats and no evidence of malnutrition at either site. However, urban squirrels had higher blood glucose, lower potassium, phosphorus, chloride, and albumin:globulin ratios. These results align with previous findings of increased dietary sugar in cities and suggest that urban populations of gray squirrels are under greater environmental stress than rural populations, providing future directions for studying physiological responses to urbanization.