DOI: 10.5061/dryad.zpc866tgc
title: Data from: Trade-offs between forage availability, accessibility, and predation risk on winter foraging strategies of wood bison (Bison bison athabascae)

description: Optimal foraging theory (OFT) and the energy maximization hypothesis (EMH)
 have long been essential when examining wildlife habitat selection. At
 high latitudes and altitudes, animals in winter face greater limitations
 in availability and accessibility of forage. Here we explore the foraging
 behavior of wood bison (Bison bison athabascae) during winter within the
 Ronald Lake bison herd in northeastern Alberta, Canada, and examine the
 trade-offs they face due to limitations in forage abundance and
 availability (snow conditions), as well as the need to minimize predation
 risk. We used Global Positioning System (GPS) location data collected from
 70 female wood bison to identify winter foraging sites and craters
 selected by bison to access forage beneath the snow. Within wetlands used
 by bison we selected 190 pairs of used (foraged) and random available
 sites to test eight a priori hypotheses explaining how bison traded-off
 between forage availability, accessibility, and minimizing predation risk.
 We found with matched-paired logistic regression that Carex atherodes was
 1.21-times more likely to be selected per unit increase in cover, compared
 to 1.17-times per unit cover for C. aquatilis and C. utriculata. However,
 all Carex species showed an increase in selection when cover was
 &gt;50% cover within individual craters. While the importance of Carex
 was clear, forage site selection was still inversely related to snow
 depth. We suggest that bison maximized their energy return by avoiding
 areas with deep snow (&gt;50 cm) that demanded intensive cratering,
 even when highly selected forage was accessible beneath. Specifically,
 there was a 1% decrease in selection of Carex per cm depth in snow when
 interacting with any Carex species. Avoidance of forage areas with deep
 snow demonstrates that wood bison employed a foraging strategy that
 considers both forage availability and environmental conditions, with snow
 depth being a limiting factor. We highlight the relationship between
 optimal foraging based on food availability and the trade-offs within an
 energy restrictive winter season, furthering the understanding of how
 large herbivores in forage strategically to maximize energy intake in
 northern environments.
description: We recorded environmental characteristics of bison selected
 foraging sites, and random paired avaliable sites during the winters of
 2020 and 2021. This dataset holds the values for snow characteristics,
 forage characteristics, and distances to nearest cover recorded from these
 sites. It is organized in a way to support a matched-pair logistic
 regression.
description: # Trade-offs between forage availability, accessibility, and predation
 risk on winter foraging strategies of wood bison (Bison bison athabascae)
 [https://doi.org/10.5061/dryad.zpc866tgc](https://doi.org/10.5061/dryad.zpc866tgc) ## Description of the data and file structure This dataset contains forage, snow, and distance data for all bison foraged (use), and random available (paired) locations collected in the winters of 2020 and 2021. All data is within file "Rawleigh_TradeoffData.csv". R-script for analysis and graphical representation of results is also provided in the file "Rawleigh_Tradeoffs_code.R" DATA-SPECIFIC INFORMATION FOR: Rawleigh_TradeoffData.csv 1. Variable List: * Pair - The number of the paired use and available sites. Each pair has a unique numeric identifier for the matched-paired logistic regression. * Use - Binary assigning the row to either use (1) or available (0). * Cluster - Number assigning the sites to the unique wetland cluster it is part of. * Constant - placeholder value used in the null model. * Hardness - hardness of snow based on the Hand Hardness scale (categorical) * CrustDepth - depth of snow crust, measured in centimeters. * TotalDepth - total depth of snow, measured in centimeters. * CrustDensity - crust density calculated from field measured snow water equivalent (presented as % density). * TotalDensity - total density calculated from field measured snow water equivalent (presented as % density). * Spaqua - Percent cover of Carex aquatilis within the crater. * SPath - Percent cover of Carex atherodes within the crater. * SPutric - Percent cover of Carex utriculata within the crater. * SPgrass - Percent cover of Poa species within the crater. * Spbrowse - Percent cover of woody plants within the crater. * SPice - Percent cover of ice within the crater. * SPcattail - Percent cover of Typha species within the crater. * Distance - distance from the nearest tree line to the center of the measured crater. 2. Missing data codes: NA 3. Specialized formats or other abbreviations used: None. ## Code/Software R-packages used in analysis included: survival, mclogit; ggplot2; ggeffects; ggtext; bbmle; patchwork.