Food may be consumed where it is found, carried to a feeding platform, or brought back to the nest. Population densities of 100-300 per ha. The average space used by one individual is only about 50 sq meters. There is little evidence of territoriality, and individuals appear to be socially tolerant, but there is only one adult occupant per house. Breeding seems to peak in the late fall and early winter but to continue to some extent throughout the year.
Females normally produce four or five litters annually.
The estrous cycle lasts 15 days or less, the gestation period is 26-29 days, and litter size averages 2.2 young and ranges from 1 to 4. The round-tailed muskrat is not usually hunted for its pelt. It may occasionally damage crops, but it is generally of little economic significance. Some populations have declined because canals have drained marshes and allowed salt-water intrusion.