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Data from: Deriving birth timing of roe deer fawns from body measurements to limit mowing mortality

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Dec 11, 2024 version files 180.82 KB

Abstract

Every spring, hiding roe deer fawns (Capreolus capreolus L.) in meadows are injured or killed by mowing activities. To assess the temporal overlap between mowing activities and the fawning period, and thus help reduce the risk of mowing death, we have determined the average parturition date in three regions of Bavaria, southern Germany.

Data on physical body parameters were collected from 1387 fawns over four consecutive springs (2020-2024). Across all of the years studied, data collection started at the end of April, independent of spring mowing activities. We searched for fawns mainly using unmanned aerial vehicles (UAV) and recorded the status of the umbilical cord, body mass, hind foot length, total body length, head length, crown-rump length, and presence of siblings of each detected fawn. A total of 118 of the 1387 fawns were found and measured multiple times. To estimate age, we fitted a generalized linear mixed model (GLMM) as a function of multiple physical parameters and subsequently determined the age and birth date of all fawns based on this predictive model. Body mass, head length, crown-rump length, and the presence of siblings were the most important predictors of fawn age (R2 = 0,74). The estimated ages were used to calculate the mean parturition dates for the region. The results show that the first fawns were born as early as April. Across years the mean parturition date was the 135 day of the year (DOY).

Our results confirmed that fawn birth dates and the hiding phase highly overlapped with spring mowing events. However, based on the derived knowledge of the exact birth times, our study can contribute to reducing mowing-related mortalityrates. Our predictive model may also provide researchers in other regions with an approach to accurately determine the ages of roe deer fawns.