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

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 subse..., Data collection
We systematically searched for roe deer fawns every day during springs (April 25 to June 30), 2020, and 2023, with four teams. Specifically, we systematically scanned agricultural areas at regular spatial intervals using unmanned aerial vehicles (UAV) (DJI Matrice 200 with a DJI Zenmuse XZ2 thermal camera, DJI Mavic 2 Enterprise Advanced with an M2EA 640p thermal camera, and Yuneec H520 with a Yuneec CGOET10 thermal camera). In addition, chains of people were formed to search for fawns in forested areas. Furthermore, in the spring of 2021 and 2023, we searched for fawns of female roe deer equipped with radio-gps collars (LiteTrack 360; LOTEK WIRELESS INC, Newmarket, Canada). Radiocollared does were monitored, and if movement parameters or physical appearance indicated birth (Baur et al., 2024), fawns were identified using thermal drones or thermal binoculars (Pulsar Accolade 2 LRF XP50).
Our search teams, of two people each, were trained in advance to take standardized m..., , # Deriving birth timing of roe deer fawns from body measurements to limit mowing mortality

[https://doi.org/10.5061/dryad.x95x69pvd](https://doi.org/10.5061/dryad.x95x69pvd)

## Description of the data and file structure

The data file included in the submission consists of Stehr_2024_Data_roe_deer_fawn.csv. The study focuses on developing a robust method for estimating the birth timing of roe deer fawns using body measurements, drawing on a comprehensive dataset of over 1.300 individuals. By achieving greater accuracy in age estimation and identifying a shift in parturition timing, likely linked to environmental adaptability, our findings have critical implications for mitigating mowing-related mortality—a topic of increasing public and scientific concern.

The integration of these results into wildlife management strategies has the potential to reduce the risk to neonate roe deer during agricultural mowing, a recurring issue that receives significant media and policy attention. Furth...