Characterization of the estrous cycle and assessment of reproductive status in Matschie’s tree kangaroo ( Dendrolagus matschiei ) with fecal progestin profiles

Abstract The population of Matschie’s tree kangaroos ( Dendrolagus matschiei ) held in North American zoos has declined to critically low numbers, and information on the reproductive biology of tree kangaroos is limited. The objectives of this study were to (1) characterize the temporal features of the estrous cycle through the measurement of fecal progesterone metabolite (i.e., progestin) concentrations and (2) determine the reproductive status of female tree kangaroos in the captive population of North America through the identification of estrous cyclicity. Fecal pellets and observations of estrous behaviors were collected from 16 captive female tree kangaroos. Fecal pellets were sampled and extracted with methanol, and progestin concentrations were quantified using a radioimmunoassay (RIA) for progesterone and its metabolites. A progestin profile was obtained for each female by plotting fecal progestin concentrations for every third day over a 120-day period. Profiles for 12 of 16 females showed evidence of estrous cyclicity ( P < 0.01). The mean length of the estrous cycle was estimated at 58.9 ± 2.4 days ( n = 11). Progestin concentrations were low during the first 15–20 days of the luteal phase and remained elevated above baseline only during the last 30.2 ± 3.2 days of the luteal phase, which averaged 46.6 ± 2.5 days in duration. The progestin profile observed in the estrous cycle of Matschie’s tree kangaroos in this study is very similar to that seen in the non-pregnant cycle of several other species in the family Macropodidae.