Abstract
Spring emergence from brumation has been studied in several terrestrial turtles, particularly box turtles (Terrapene spp.) and tortoises (Gopherus spp.). However, most research involved small samples (often captive), excluded juveniles, lasted only 1 or a few years, and/or used only estimates of emergence dates. We quantified brumation emergence dates for 14,668 Yellow Mud Turtles (Kinosternon flavescens) captured from a population in the Sandhills of Nebraska between 1983 and 2018. Average spring emergence date over 9 yr for 1961 adult (≥ 85 mm carapace length) males was 1 May and for 2882 females was 5 May. For 5985 juveniles and 3840 hatchlings it was each 21 May over 12 yr. However, these means varied by about 3 wk among years, and emergence seasons for each cohort were typically about 40 d in length. Average emergence date across years for adult males and females was related primarily to spring temperatures. Predicted emergence for adults began when mean minimum and maximum temperatures over the past 2 d reached approximately –6.0°C and 7.0°C, respectively. Average dates for juveniles and hatchlings were not correlated with general patterns of spring weather; however, the combination of warm temperatures for several days with rainfall stimulated the most emergence. Emergence date was inversely related to body size and age. Females that nested in a respective year of emergence had better body condition, but did not emerge earlier than those that did not. Although spring emergence was influenced by temperature and moisture, precise timing varied primarily by individual and year.
