Changes in Fecal Glucocorticoid Metabolites in Captive Coyotes (Canis latrans): Influence of Gender, Time, and Reproductive Status

Abstract

Reproduction is considered an energetically and physiologically demanding time in the life of an animal. Changes in physiological stress are partly reflected in changes in glucocorticoid metabolites and can be measured from fecal samples. We examined levels of fecal glucocorticoid metabolites (fGCMs) in 24 captive coyotes (Canis latrans) to investigate responses to the demands of reproduction. Using 12 pairs of coyotes (five pairs produced pups, seven pairs did not), we analyzed 633 fecal samples covering 11 biological periods (e.g., breeding, gestation, and lactation). Levels of fGCMs showed high individual variability, with females having higher fGCM levels than males. The production of pups showed no statistical effect on fGCM levels among females or males. Among females, fGCM levels were highest during 4-6 weeks of gestation compared to other periods but were not significantly different between pregnant and nonpregnant females. Among males, the highest fGCM levels were during 1-3 weeks of gestation compared to other periods, but were not significantly different between males with a pregnant mate versus nonpregnant mate. Of females producing pups, litter size did not influence fGCM levels. Given that they were fed ample food throughout the year, we found that the demands of producing pups did not appear to statistically influence measures of fGCM concentrations in captive coyotes.

Keywords: Canis latrans; breeding; canid; carnivore; cortisol; coyote; fGCM; fecal glucocorticoid metabolites; non-invasive.

Figure 1

Mean and standard deviation of fecal glucocorticoid metabolite (fGCM) levels for captive females (F) and males (M); * indicates individuals with pups.

Figure 2

Mean and standard deviation of seasonal fecal glucocorticoid metabolite (fGCM) levels for captive female and male coyotes across 12 months. Time periods are pair bonding and reinforcement (Pbr), mate attraction and copulation (Br), 1–3 weeks into gestation (G1–3), 4–6 weeks into gestation (G4–6), 7–9 weeks into gestation (G7–9), 1–3 weeks into lactation (L1–3), 4–6 weeks into lactation (L4–6), after pups are weaned (Pw), 1–3 weeks after pups are removed (Pr1–3), 4–6 weeks after pups are removed (Pr4–6), and the non-reproductive season (Ot).

Figure 3

Fecal glucocorticoid metabolite (fGCM) levels for female coyotes (A) with pups and (B) without pups across 12 months. Time periods are: 1–3 weeks into gestation (Gest3), 4–6 weeks into gestation (Gest6), 7–9 weeks into gestation (Gest9), 1–3 weeks into lactation (Lact3), 4–6 weeks into lactation (Lact6), after pups are weaned (Post weaning), 1–3 weeks after pups are removed (Pups remove3), 4–6 weeks after pups are removed (Pups remove6), non-reproductive season (Other), Pair bonding and reinforcement (Pair BR), and mate attraction and copulation (Breeding). * indicates animal was originally in the breeding cohort but failed to produce pups, thus classed as a female without pups.

Figure 4

Fecal glucocorticoid metabolite (fGCM) levels for male coyotes (A) with pups and (B) without pups across 12 months. Time periods are 1–3 weeks into gestation (Gest3), 4–6 weeks into gestation (Gest6), 7–9 weeks into gestation (Gest9), 1–3 weeks into lactation (Lact3), 4–6 weeks into lactation (Lact6), after pups are weaned (Post weaning), 1–3 weeks after pups are removed (Pups remove3), 4–6 weeks after pups are removed (Pups remove6), non-reproductive season (Other), Pair bonding and reinforcement (Pair BR), and mate attraction and copulation (Breeding). * indicates animal was originally placed in the breeding cohort but failed to produce pups, thus was classed as a male without pups.