DOI: 10.5061/dryad.hdr7sqvt4
title: Wood bison migration metrics and environmental covariates

description: Migration is an evolutionarily stable adaptation when movement costs are
 outweighed by fitness gains. Migration is defined as the predictable
 movement between seasonal ranges in response to differential resource
 availability. However, migrations to locate suitable mates, and calving or
 nursery grounds are also common across taxa. For ungulates, the growth of
 new vegetation (i.e., green-wave) has been identified as a key mechanism
 influencing migration between seasonal ranges. We investigated how the
 green-wave influenced migration in a wood bison (Bison bison athabascae)
 population in northern Alberta, Canada, while also considering risk of
 calf predation by wolves (Canis lupus). Each year, all collared females in
 the population migrated an average of 28-kilometers over 6-days to a
 region at the western edge of their annual range between late-May and
 early-June. By late-June they migrated back to their core range, averaging
 a 40-kilometer migration distance over 10-days. We found that the
 green-wave influenced both the timing of migration and selection of
 habitats during migration. Risk of predation was not found to influence
 habitat selection during migration. However, the herd congregating and
 leaving their spring range as a group suggests risk of predation may be an
 evolutionary mechanism contributing to this migratory behavior. The timing
 of migration and congregation aligns with the expected timing of
 parturition giving further support that both the green-wave and predation
 risk influence migration. We provide a framework to assess interrelated
 mechanisms influencing migration, which is important to those studying,
 managing, and/or conserving migratory ungulates.
description: # Ronald Lake wood bison migration dataset (2013 - 2019)
 [https://doi.org/10.5061/dryad.hdr7sqvt4](https://doi.org/10.5061/dryad.hdr7sqvt4) ## Description of the data and file structure Between 2013 and 2019, 58 females were fitted with Global Positioning System (GPS) collars by Alberta Environment and Protected Areas at a 1.5-hr fix-rate for various lengths of time (n = 38 Lotek Newmarket, Canada; 10 Vectronics Berlin, Germany; 10 Tellus Lindenberg, Sweden). We observed an annual spring migration by all females (i.e., complete migration; Avgar et al., 2014) in May or early-June to a distinct region near where the McIvor River exits the Birch Mountains (hereafter referred to as the “spring range”; Figure 1). We calculated instantaneous rate of green-up (IRG) as the first derivative of the positive slope of the normalized difference vegetation index (NDVI; MOD9Q1 product from MODIS terra satellite) curve for a given 250×250-m cell ### Files and variables #### File: StudyArea\_MaxDates*\_*published.csv **Description:** Dataset including dates of of maximum normalized difference vegetative index and instantaneous rate of green-up across the bison's home range. ##### Variables * Date_Time: Date and time single variable in the Mountain Time Zone. * Date: Date (MM/DD/YYYY), Mountain Time Zone * Time: Time (HH:MM:SS), Mountain Time Zone * Latitude: latitudinal decimal coordinates (WGS 1984) * Longitude: longitudinal decimal coordinates (WGS 1984) * Year: Year * Day: Julian day * Migration: ingress (migration to the calving range) or egress (migration out of the calving range) * EWC: Duck's Unlimited's enhanced wetland classification for landcover types * | 1 | Open Water | | :- | :----------------- | | 2 | Aquatic Bed | | 3 | Mudlfats | | 5 | Emergent Marsh | | 6 | Meadow Marsh | | 7 | Graminoid Rich Fen | | 8 | Gramonoid Poor Fen | | 9 | Shrubby Rich Fen | | 10 | Shrubby Poor Fen | | 11 | Treed Rich Fen | | 12 | Treed Poor Fen | | 13 | Open Bog | | 14 | Shrubby Bog | | 15 | Treed Bog | | 16 | Shrub Swamp | | 17 | Hardwood Swamp | | 18 | Mixedwood Swamp | | 19 | Tamarack Swamp | | 20 | Conifer Swamp | | 21 | Upland Conifer | | 22 | Upland Deciduous | | 23 | Upland Mixedwood | | 24 | Upland other | | 25 | Cutblock | | 26 | Agriculture | | 27 | Antropogenic | | 28 | Cloud | | 29 | Cloud Shadow | | 30 | Burn | | 33 | Upland Pine | * ndvi: normalized difference vegetative index * IRG: instantaneous rate of green-up * 16MaxIRGJD: Julian day of MAXIMUM IRG value per cell * 16MaxNDVI: Julian day of Maximum NDVI value per cell #### File: SSFAnalysis.csv **Description:** Covariates associated with bison and random locations used to conduct step selection function (SSF) analysis. Due to the conservation status of the Ronald Lake wood bison population and our data sharing agreement with Alberta Environment and Parks (manager of collar data) the coordinates associated with each location have been removed. However, the SSF analysis can still be conducted as the BPoint\_ ID * *and Random\_ ID vectors identifying the sequence of bison locations and the associated random locations. ##### Variables * ID: Identification unique to each point. * Location: Bison or random * Binomial: 1= bison or 0 = random * BPoint_ID: Bison point ID. NA for all random locations. * Unique_ID: Same as "ID". * Device_ID: Bison collar number. NA for all random locations. * Random_ID: Random ID to associate it with a bison location. NA for all bison locations. * Date_Time: Date and time single variable in the Mountain Time Zone. Note that no date or time is included for random locations as they are determined based on the bison location. * Date: Date (MM/DD/YYYY), Mountain Time Zone. Note that no date or time is included for random locations as they are determined based on the bison location * Time: Time (HH:MM:SS), Mountain Time Zone. Note that no date or time is included for random locations as they are determined based on the bison location * Year: Year * Day: Julian day * Migration: Ingress or egress migration period * NDVI: normalized difference vegetative index * IRG: instantaneous rate of green-up * NDVI2: squared NDVI * inWolf_BBM: kernal density estimate of wolf dBBM during ingress * egWolf_BBM: kernal density estimate of wolf dBBM during egress * LC: Duck's Unlimited's enhanced wetland classification for landcover types * | 1 | Open Water | | :- | :----------------- | | 2 | Aquatic Bed | | 3 | Mudlfats | | 5 | Emergent Marsh | | 6 | Meadow Marsh | | 7 | Graminoid Rich Fen | | 8 | Gramonoid Poor Fen | | 9 | Shrubby Rich Fen | | 10 | Shrubby Poor Fen | | 11 | Treed Rich Fen | | 12 | Treed Poor Fen | | 13 | Open Bog | | 14 | Shrubby Bog | | 15 | Treed Bog | | 16 | Shrub Swamp | | 17 | Hardwood Swamp | | 18 | Mixedwood Swamp | | 19 | Tamarack Swamp | | 20 | Conifer Swamp | | 21 | Upland Conifer | | 22 | Upland Deciduous | | 23 | Upland Mixedwood | | 24 | Upland other | | 25 | Cutblock | | 26 | Agriculture | | 27 | Antropogenic | | 28 | Cloud | | 29 | Cloud Shadow | | 30 | Burn | | 33 | Upland Pine | * DWater: distance to water * CTI: compound topographic index * Dline: distance to linear disturbance * iNDVI: integrated NDVI * Distance: Distance between steps * BisonRandom_ID: Bison location ID used to associated random locations ## Code/software All analyses conducted in R studio.