Activity times of animals are often determined by changes in temperature, ambient light, predator abundance, or resource availability. Ground and wood-dwelling ants have particularly strong responses to fluctuations in temperature and light, due their ability to use nests as thermal refugia when environmental conditions become unfavorable. Through the selective foraging times of local ant species, ant communities fluctuate in species composition. In order to determine the role of temperature fluctuations on seasonal and diel scales in structuring ant communities in time, I built time-sorting pitfall traps with built-in thermocouple dataloggers to capture 1-hour intervals of ant activity. I then deployed these time-sorting pitfall traps June-October at Sagehen Creek Reserve near Truckee, CA, to investigate activity patterns of species occurrence over the course of the day.
Average activity times varied by species, month, and canopy cover, with several species demonstrating crepuscular patterns of activity. Litter depth had a large impact of the identity and number of species encountered, the time ants were active, and the extent of species overlap in foraging times. No ants were found to be truly nocturnal, with average nighttime lows near freezing. Similarly, few ants persisted in the hottest environments monitored in mid afternoon.