The adult population increased from ten in August 1956 to 14 in June 1957. During the summer of 1957 there was some fluctuation in numbers as three yearlings left the colony, but would reappear from time to time. It was possible to identify all the adults as to sex except one. All were females except the unidentified one. This same animal has been observed for three years and is believed from certain behavioral characteristics to be a male. There were five litters of young with a total population of twenty-five. There were sixteen females and nine males. Project Number 82.
Armitage, Kenneth B.
"Ecology and Behavior of the Yellow-bellied Marmot,"
Jackson Hole Research Station Annual Report: Vol. 1957
, Article 3.
Available at: https://repository.uwyo.edu/jhrs_reports/vol1957/iss1/3