Monitoring Reproduction in Captive Moose Using Urinary and Fecal Steroid Metabolites

Because repeated capture, restraint, and blood sampling generally are impractical strategies for monitoring reproductive status in wildlife species, noninvasive methods for tracking reproductive activity have become increasingly important. Thus, we used radioimmunoassay (RIA) of urinary pregnanediol-3α-glucuronide (PdG), estrogen conjugates, and fecal progesterone and estradiol to assess estrous cycles and pregnancy in captive moose (Alces alces). Using urinary PdG, we identified distinct reproductive cycles that began during October, and estrus behavior that coincided with nadirs in PdG excretion. Although PdG increased up to 5-fold over cycling levels during pregnancy, concentrations were variable making pregnancy diagnosis equivocal using this method