DOI: 10.5061/dryad.s4mw6m96q
title: Deer-vehicle collisions in Denmark

description: Vehicles collide with hundreds of thousands of deer on European roads each
 year. This leads to animal deaths and suffering, economic damage and risks
 for human safety, making the reduction of road mortality a major field in
 conservation biology. In order to successfully reduce roadkill, we need
 improved knowledge regarding spatio-temporal patterns of deer-vehicle
 collisions (DVCs) on a landscape scale. Here, we analyzed &gt;85,000
 DVCs collected over 17 years in Denmark to investigate changes in the
 number of DVCs over time and to find spatio-temporal patterns of DVC
 occurrence. We used a use-availability design – originally developed for
 habitat selection analyses – to compare DVCs involving roe deer (Capreolus
 capreolus), red deer (Cervus elaphus) and fallow deer (Dama dama) with
 random road locations on a landscape scale. This approach enabled us to
 combine temporal (seasonal and diel variation), spatial (land cover, road
 density and type) and other relevant variables (deer population density,
 traffic, and deer activity) within the same analysis. We found that
 factors related to infrastructure and land cover were most important in
 explaining patterns of DVCs, but seasonal and diel changes, deer activity,
 and population density were also important in predicting the occurrence of
 DVCs. Importantly, patterns of DVCs were largely similar between the three
 deer species, with more DVCs occurring at intermediate traffic density,
 increasing forest cover, during dusk and dawn, and with increasing deer
 activity and population density. The strong and consistent patterns found
 here will allow the development of flexible mitigation measures. We
 propose that our findings could be used to develop a spatio-temporally
 flexible warning system for smartphones and navigation systems that is
 based on existing map providers, making it a widely available and cheap
 mitigation measure.
description: Data on deer-vehicle collisions for roe deer (<i>Capreolus
 capreolus</i>), red deer (<i>Cervus elaphus</i>), and
 fallow deer (<i>Dama dama</i>) were collected countrywide in
 Denmark (Fig. 1). A corps of hunters, supervised under the
 “Schweiss-register” by the Danish Nature Agency, conducted tracking and
 euthanasia of traffic-injured deer with specially trained tracking dogs.
 From 2003-2010, it was mandatory for tracking dog handlers to register the
 exact location of DVCs, date and time for all DVCs they were called for,
 as well as information on species, sex and age class if available. From
 2011-2016, only the number of annual DVCs was registered without
 information on spatial location (not shown in this data set), but from
 2017-2019 the spatial location was again registered although not the time
 of day.
description: Coordinates (Lat/Lon) are given in WGS 1984. Fawns/calves were
 defined as individuals in their first year of life (May 1 was used as
 cut-off date), yearlings as individuals in their second year of life, and
 adults all individuals &gt;2 years. Roads were categorized into (1)
 ≥3-6 m wide (speed limit 50-80 km/h), (2) &gt;6 m wide (speed limit
 50-80 km/h), (3) expressways (speed limit 80-110 km/h, with restrictions
 on traffic types and grade crossings), and (4) motorways (speed limit
 80-130 km/h, multilane road with controlled access and no grade
 crossings). Land cover types were categorized into arable fields, built up
 areas (including any property in the country with a building on it, i.e.,
 including gardens, farmsteads etc.), heathland, fallow (areas taken out of
 agricultural production), forest, water bodies, and pastures.