DOI: 10.5061/dryad.8sf7m0d1n
title: Data for: Behavioral responses of migratory caribou to semi-permeable roads in Arctic Alaska

description: Migration conveys many benefits to species, ecosystems, and people, but
 relies upon connected landscapes. Anthropogenic development can present
 barriers for migrants, but many barriers are semi-permeable, allowing
 unhindered or delayed passage. We use a modified version of the Barrier
 Behavior Analysis (BaBA) to investigate movement responses and
 permeability of roads in northwestern Alaska by adult female Western
 Arctic Herd caribou (Rangifer tarandus) from 2009–2024. These data include
 the BaBA results that we used to reveal behavioral responses to roads by
 study caribou. Our analyses revealed movement responses to all five focal
 roads. We found that the roads were semi-permeable barriers to movement,
 with altered behaviors including bouncing away, moving back-and-forth, and
 tracing along roads. Overall, 63.1% of collared animals encountered
 (entered a road-specific buffer) at least one focal road. Of these, 61.5%
 displayed altered movements. At the scale of individual encounters with
 roads, we found altered movement in 27.1% of road encounters. Each row of
 the dataset represents one burst, indicating subdivisions of road
 encounters that reflect specific behavioral responses. Encounter timing is
 also indicated for each record. Most encounters occurred during fall
 migration, and caribou with altered behavior spent longer near focal roads
 than those with unaltered movement. We confirm prior findings of altered
 fall movements near the Red Dog road and demonstrate that movement
 behavior is also altered around other roads and in other seasons.
 Nonetheless, many collared caribou did not display altered movements in
 response to roads, emphasizing the need for further research to understand
 the mechanistic drivers of caribou movement responses. Given increasing
 pressures for infrastructure development and global challenges facing
 migratory species, it is critical to identify mitigation measures and
 inform management decisions seeking to balance responsible development
 with conservation of natural systems, including migratory species and the
 people that rely upon them.
description: # Data for: Behavioral responses of migratory caribou to semi-permeable
 roads in Arctic Alaska Dataset DOI:
 [10.5061/dryad.8sf7m0d1n](10.5061/dryad.8sf7m0d1n) ## Description of the
 data and file structure We investigated movement responses to roads for
 caribou (*Rangifer tarandus*) in northwestern Alaska. We ran GPS telemetry
 data for 366 adult female caribou through a modified version of the
 Barrier Behavior Analysis (BaBA) tool, resulting in this dataset. The BaBA
 compares movement parameters near a potential barrier with those away from
 barriers to identify altered movement behavior. We heavily modified the
 original BaBA methodology for this analysis. The resulting dataset
 indicates interactions with roads at the encounter and altered burst
 scales, including information about timing and behavioral responses. ###
 Files and variables #### File: WAH_BaBA_Data_2025-05-09.csv
 **Description:** Behavioral responses of adult female caribou of the
 Western Arctic Herd to roads in northwestern Alaska as indicated by our
 modified Barrier Behavior Analysis (BaBA). Each row of the dataset
 represents one burst (see definition below and in the study text) analyzed
 in this study. For details of how these behaviors were identified from
 caribou GPS telemetry data, see the Methods of this study and details in
 Supplementary Information 1. ##### Variables * AnimalID: Unique
 alphanumeric identifier for each caribou analyzed in the dataset. Some
 AnimalIDs are completely numeric while others also include letters. *
 encounter: Unique identifier for each encounter of a caribou with a road,
 encompassing the time from which a caribou entered a focal road buffer
 until it left that buffer. Encounters take the Animal_ID followed by a
 numeric indicator to distinguish the potential for multiple encounters per
 caribou. * burstID: Unique identifier of each burst analyzed by the BaBA.
 Bursts represent subdivisions of an encounter, identified by a focal road
 being crossed or, in the event of overlapping road buffers (Red Dog –
 Kivalina only), the animal moving from being closer to one focal road to
 another while remaining within the buffers. Bursts were used to identify
 multiple behavioral responses to a single focal road or to multiple nearby
 roads with overlapping buffers. The burstID matches the encounter
 identifier with a possible additional numeric indicator if there were
 multiple bursts for a given encounter. * start_time: The start time for
 the movement step in which a caribou entered a focal road buffer or
 started a new burst within an encounter. Times are reported here in
 Universal Coordinated Time (UTC) but were converted to the local Alaskan
 time zone (tz = "America/Anchorage") using the lubridate package
 in R for assignment of seasons and for the other analyses reported in our
 study. All telemetry location times were rounded to the nearest hour, as
 this was their target capture time. * end_time: The end time for a
 movement step in which a caribou left a focal road buffer or ended a burst
 within an encounter. Times are reported here in Universal Coordinated Time
 (UTC) but were converted to the local Alaskan time zone (tz =
 "America/Anchorage") using the lubridate package in R for
 assignment of seasons and for the other analyses reported in our
 study. All telemetry location times were rounded to the nearest hour, as
 this was their target capture time. * duration_hrs: The duration of the
 burst in hours, indicating the time between start_time and end_time. *
 season: The season of the year in which the burst took place. Seasons
 reflect biologically relevant periods of similar caribou behavior,
 following Joly and Cameron 2024. Seasons included: *spring migration*,
 *calving*, *insect harassment*, *late summer*, *fall migration*, and
 *winter*. Bursts were assigned to the season which occupied the majority
 of the burst locations. * road: Indication of the road with which the
 caribou interacted at the encounter scale. The encounter scale reflected
 all bursts within an encounter combined into a single representation of an
 interaction with a road or set of roads. We combined the Red Dog and
 Kivalina road responses at the encounter scale as their overlapping
 buffers often led to joint reactions in proximity to both roads within a
 single encounter. Possible roads included: *Dalton*, *Kobuk*, *Nome*,
 and *Red Dog - Kivalina*. Please see the Methods section of the study for
 descriptions of each road. * encounter_scale: Behavioral response of the
 caribou at the encounter scale. Behavior was reduced to a binary of
 unaltered or altered movement. * *Unaltered movement* - Movements
 indistinguishable from season-specific movement in the absence of focal
 roads or for which crossing did not appear hindered. These consisted of
 normal movement and quick cross behaviors. * *Altered movement* - Periods
 where movement behavior changed near a focal road compared to seasonal
 average movement parameters outside of road buffers. These consisted of
 back-and-forth, bounce, and trace behaviors. If any of the bursts within
 the encounter featured altered movement, then the encounter was classified
 as altered. * burst_scale: Behavioral response of the caribou at the burst
 scale. Each burst was assigned a movement behavior by the BaBA (details in
 Methods and Supplementary Information 1). Possible values included: *
 *Normal movement* - Movement in which movement parameters fell within
 seasonal average parameters or all locations in the burst were closest to
 the same point on the road (identifying situations where a caribou briefly
 dipped inside a buffer and then exited again rapidly). * *Quick cross*
 - Rapid, linear movement across one or more focal roads, without apparent
 hindrance by the road. * *Back-and-forth* - Clustered movement near a
 focal road, with repeated changes in movement direction leading to
 relatively confined space use. * *Bounce* - Movement in which a caribou
 approached a focal road and then bounced back away, typically without
 crossing. * *Trace* - Movement in which a caribou paralleled a road for a
 sustained amount of time. * crossing: Binary indication of whether the
 caribou crossed the closest_rd during the indicated burst (1) or not (0).
 This corresponds to the cross_true parameter in Supplementary Fig. S1 as
 it  distinguished between true and false crossings by testing for
 locations on either side of a road. If all locations were on the same side
 of a road, we assumed this indicated a false crossing (i.e., when the
 straight line between subsequent locations might falsely indicate that a
 crossing occurred). Thus, crossing only takes a value of 1 when a crossing
 is indicated *and* locations occur on both sides of a road. *
 closest_rd: Indication of the road with which the caribou interacted at
 the burst scale. At the burst scale, interactions with each road could be
 distinguished. Thus, possible values included: *Dalton*,
 *Kivalina*, *Kobuk*, *Nome*, and *Red Dog*. Please see the Methods section
 of the study manuscript for descriptions of each road. * closest_dist_km:
 Numeric indicator of the distance between the closest recorded telemetry
 location and closest_rd, in units of kilometers. Note that this is the
 closest observed distance but may not reflect the closest the caribou
 actually came in between recorded locations. For example, any caribou that
 crossed the road would have an actual closest distance of 0 km. This was
 calculated by taking the minimum distance between the telemetry locations
 for a given burst and the line locations of closest_rd, using the
 st_distance function of the sf package in R. ## Code/software Code for
 running our modified Barrier Behavior Analysis (BaBA) tool is available
 at [https://github.com/tfullman/BaBA](https://github.com/tfullman/BaBA).