Ungulate substrate use in fauna passages
Data files
Jul 30, 2025 version files 2.51 MB
Abstract
This dataset describes the substrate used by ungulates when crossing through fauna passages (n=7) in boreal Sweden and Finland, as well as the trajectories of the ungulates when crossing. Data of crossing events in the Excel file and the spatial maps are linked by the "Count" number. For each crossing event, date and time, any occurrence of snow, group size, and the animal´s direction of movement are given. As additional information, details of the seven fauna passages (location, dimensions, disturbances, and the monitoring period) are provided.
Dataset DOI: 10.5061/dryad.5mkkwh7j1
Description of the data and file structure
We have submitted our data on ungulate crossing events through fauna passages (Ungulate_crossing_events_through_fauna_passages_Data.xlsx) and complemented with illustrations of trajectories of each crossing event (Ungulate_crossning_events_through_fauna_passages_Spatial_maps_of_trajectories.pdf). We also provide general info about the study sites (Ungulate_crossning_events_through_fauna_passages_General_info_of_fauna_passages.pdf).
File: Ungulate_crossning_events_through_fauna_passages_General_info_of_fauna_passages.pdf
- Location: Coordinates of the site (in WGS84)
- Technical label: The number of the bridge in the Swedish Transport Administration´s bridge database
- Construction year: The year the bridge was constructed
- Infrastructure crossed: The name and type of the major infrastructure that the bridge crosses
- Width: Width of the fauna passage; available width for the fauna, in meters, measured between perimeter fences
- Height: Height of the fauna passage (underpasses); available height for the fauna, in meters, measured between ground and ceiling
- Length: Length of the fauna passage; distance that fauna have to pass from one side of the infrastructure to the other, in meters, as subjectively assessed from surrounding habitats and the extended fence line along the infrastructure
- Traffic through passage: Mean number of motorized vehicles through the passage per day (24h)
- Other human activities in passage: Mean number of non-motorized human disturbances in the passage per day (24h)
- Monitoring start: Date when camera monitoring started (yyyy-mm-dd)
- Monitoring end: Date when camera monitoring ended (yyyy-mm-dd)
- Number of days: Total number of days that the fauna passage was effectively monitored
- Substrates available: Total width of each substrate along the record line, in meters, and the total width of the record line
File: Ungulate_crossning_events_through_fauna_passages_Spatial_maps_of_trajectories.pdf
Spatial maps of individual trajectories (events), separated by site, species, and season (snow-free or snow-covered ground).
Each map shows:
- Individual trajectories; blue solid arrows, serial numbers referring to column G in the file Ungulate_crossning_events_through_fauna_passages_Data.
- Camera placement(s); red symbols, also showing the direction of the camera
- Record line; blue hatched line, along which the substrate use was recorded
- Perimeter fencing of the passage; wider light blue line
- Substrates; extent of substrates along the record line
File: Ungulate_crossning_events_through_fauna_passages_Data.xlsx
Description of columns
- Country: Sweden or Finland
- Site: Study site, referring to sites described in the file Ungulate_crossning_events_through_fauna_passages_General_info_of_fauna_passages.pdf
- Type of passage: Underpass (bridge for passage under the major infrastructure) or overpass (bridge for passage over the major infrastructure)
- Species English: Common name in English
- Species Scientific: Current scientific name
- Snow-covered ground: Any snow cover on the ground (Yes or No)
- Count: Serial number of crossing event, referring to the respective map in the file Ungulate_crossning_events_through_fauna_passages_Spatial_maps_of_trajectories
- Date: Date of event (yyyy-mm-dd)
- Time (start): Time when the event started (hh:mm:00)
- Direction: The animals’ direction through the passage (north or south)
- Number of individuals: The number of unique individuals involved in the event (=”group size”)
- Substrate: The substrate used when crossing the record line in the middle of the passage, separated into:
- Grassy/sandy = spontaneous herbaceous or graminoid vegetation on sandy soil
- Stony/rocky = stones or rocks (> ca 5 cm) sometimes with sparse herbaceous vegetation
- Fiber mat = artificial coco liner ca 5 cm thick, rolled out on stony/rocky substrate
- Shrub = woody vegetation ca 0.5–2 m height, mainly with ground covered by low vegetation)
- Water = river or stream; open water, ice covered in winter
- Road = local gravel or dirt road
We selected fauna passages for the study on the following criteria: i) minimum width 20 m and containing a variety of substrates (≥2) to allow animals to actively select substrate, ii) passage monitored for at least 1 year, iii) camera trap set up allowed equal (unbiased) coverage of the entire passage width. We monitored ungulates in the passages using motion-triggered cameras (Browning 2017 Spec Ops Advantage Trail in the Swedish passages, Uovision UM785-3G in the Finnish passages) with an infrared (IR) motion sensor, IR flash, and IR night vision. The trigger speed of cameras was 0.4 sec (Browning) or 0.6 sec (Uovision), cameras were set to rapid fire 3–5 images when being triggered, thereafter with a delay of 5 sec (Browning) or 60 sec (Uovision) to the next triggering. We mounted the cameras in the middle of the passages, at approximately 1 m above ground, attached to pre-existing fence poles or, in a few cases, new poles. We placed the cameras on one or both sides of the passage and facing the passage center (see spatial maps), and in one case, we also mounted cameras near a structure’s center pillar and facing the sides, accordingly aiming at covering the entire width of the passage. We revisited cameras once per 1–3 months in order to check functionality and download images. Ungulate use was recorded for a minimum of one year.
We defined a crossing event as all consecutive recordings of ungulates (either single individuals or groups of conspecifics) at a passage separated by at least 10 min from the next recording. This time limit was set to avoid the most immediate temporal dependence between observations. We used only events that we judged showing animals successfully crossing the passage, i.e., coming in from one side and leaving towards the other. For each event, we noted the ungulate species and any occurrence of snow cover (as viewed from images), the date and time (start of event), the direction of movement (north or south), and the number of individuals involved (group size). We excluded a small number of crossing events where species could not be definitively identified (roe/white-tailed deer; Finnish data). For each event, we recorded the substrate where the animal crossed a predefined imaginary line over the passage in front of the cameras (hatched line in spatial maps). In the case of groups, we recorded only the first crossing individual, since we assumed that the other individuals in the group were likely to follow the trail of the first rather than make an independent decision.
Substrates were defined as follows: 1. Grassy/sandy = spontaneous herbaceous or graminoid vegetation on sandy soil, 2. Stony/rocky = stones or rocks (> ca 5 cm) sometimes with sparse herbaceous vegetation, 3. Fiber mat = artificial coco liner, ca 5 cm thick, rolled out on stony/rocky substrate, 4. Shrub = woody vegetation ca 0.5–2 m height, mainly with ground covered by low vegetation), 5. Water = river or stream; open water, ice covered in winter, 6. Road = local gravel or dirt road. Substrates, grassy/sandy, and road were only represented in the overpasses, while stony/rocky, fiber mat, and water were only represented in the underpasses. As a complement, we mapped each trajectory on a spatial map.