e rapid multi-clutch mating system of the Mountain Plover (Charadrius montanus) is an opportunity to examine sex-specific differences in uniparental care. We monitored nocturnal incubation activity in Phillips County, Montana using video recordings and temperature data-loggers. Possible differences in activity were modeled using the duration of nest departures of incubating adults. We examined the effects of sex, time of departure, nest age, day of season, maximum temperature, precipitation the previous day, and year on nest departures. We recorded 857 hours of video at 25 nests and >10,000 hours of temperature data from 142 nests during the 2006-2008 breeding seasons. Males contributed 1925 nocturnal departures with a mean duration of 0.38 hr (SE = 0.01) while females contributed 2,716 nocturnal departures with a mean duration of 0.36 hr (SE = 0.01). The time of the nocturnal departure was the only factor that had a strong effect on the duration of the departure. Our study furthers knowledge of incubation patterns in an uncommon mating system and helps understand the behavior of this species of conservation concern.