Avoiding mortality: timing prescribed burns in ornate box turtle habitat

Abstract

Fire is a vital management tool for maintaining prairie ecosystems. Prescribed burns control invasive species, regulate succession, stimulate plant growth, and are a cheap and effective method for removing excess biomass; however, fire can also inadvertently cause wildlife mortality, placing land managers in a challenging situation. Turtles are especially at risk of mortality from fire because of their low mobility and population sensitivity to reductions in adult survival. We studied ornate box turtles (Terrapene ornata) at 3 sites in Illinois, USA, from 2019–2022 to determine the best predictors of above‐ground activity so land managers can conduct prescribed burns when turtles are underground. We used turtle shell temperature, air temperature, soil temperature, and precipitation data to develop a predictive model of above‐ground activity. The best model for predicting above‐ground activity included an interaction between day of year and current air temperature. Earlier in spring and later in fall, above‐ground activity is more likely at higher air temperatures compared to later in spring and earlier in fall when the same likelihood of above‐ground activity is predicted at lower air temperatures. In spring, we recommend burning in Illinois ornate box turtle habitat before 1 April when air temperature is <10°C and in fall after 1 November when air temperature is <15°C. Above these temperature thresholds, there is a >5% likelihood that turtles in northern populations are above ground.

Evaluating population persistence of ornate box turtles (Terrapene ornata) at the northeast edge of their distribution

“…We recommend wildlife managers working to recover declining ornate box turtle populations focus efforts on reducing mortality related to three common prairie management practices: prescribed burns, vegetation mowing, and vehicle use in turtle habitat. Prescribed burns should occur as early as possible in spring and as late as possible in fall to coincide with when turtles are underground for winter (Milanovich et al 2017, Buchanan et al 2021, Edmonds et al 2023a). Vegetation mowing is another common cause of adult box turtle mortality Metcalf 1985, Doroff andKeith 1990).…”

“…Data are available from the Illinois Data Bank: https://doi. org/10.13012/B2IDB-6384815_V1 (Edmonds et al 2023b).…”