Saving Bambi from the mower? Using a drone with thermal camera to evaluate a low-tech scaring technique to reduce roe deer fawn mortality during grass harvest

Roe deer is a species that hides their neonates as an anti-predator strategy. This may prove efficient against mammalian predators, such as the red fox; however, it might be an ecological trap as large numbers of fawns are killed by tractors with harvesters each year during grass harvest. Here, we evaluate a low-tech, low-cost method, using scaring flags placed in the field the evening before grass harvest, intended to stimulate the roe deer doe to remove any fawns from the field. We evaluate the effects of the scaring flags by counting the number of fawns in the fields using a multi-rotor drone equipped with a thermal camera. The drone proved to be an efficient tool for detecting roe deer fawns. However, contrary to other studies, we found limited or no effect of placing the scaring flags in the field. This discrepancy highlights the fallacy of generalizing based on single case studies. There is still a need to develop low-cost, easily applicable tools to reduce roe deer fawn mortality..., The study was conducted in Nærøy Municipality, Nord-Trøndelag County (64° 48’ N, 11° 16’ E,). The landscape features a mixture of agricultural fields (mainly grass production for livestock feed), and forest patches. The field size of the area is rather small, with an average surveyed field size of 2.4 ha.
Experimental setup
In mid-June 2017 and end of May to mid-June 2018 we surveyed fields prior to grass harvest, using a drone equipped with a thermal camera (see “Drone setup” below). In 2017 we surveyed 38 fields and in 2018 we surveyed 69 fields. Roe deer fawns leave clearly visible heat signatures in the field in the early morning before the sun warms up the grass and reduces heat contrast.
We utilized an experimental design where we first surveyed fields using drones in the morning (07:00-10:00), then randomly selected fields for the treatment and control groups. We surveyed the same fields with drones a second time the following morning (07:00- 10:00). The 2nd flight represents the..., # Data from: Saving Bambi from the mower? Using a drone with thermal camera to evaluate a low-tech scaring technique to reduce roe deer fawn mortality during grass harvest

Dataset DOI: [10.5061/dryad.rfj6q57q0](https://doi.org/10.5061/dryad.rfj6q57q0)

Dataset from Vogler et al \"Saving Bambi from the mower? - Using a drone with thermal camera to evaluate a low-tech scaring technique to reduce roe deer fawn mortality during grass harvest\" published in Wildlife Biology, DOI: 10.1002/wlb3.01450.

Study was conducted in Nærøy Municipality, Trøndelag County, Norway in May and June of 2017 and 2018.

Dataset contains a unique grass field ID, with the number of roe deer (Capreolus capreolus) fawns detected using a drone with thermal camera. We utilized an random experimental design, where we deployed scaring devices (Plastic flags on sticks) on half of the fields to deter roe deer does from the fields. Each field was flown twice /before and after deployment of scaring devices).

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