Behavior and diet data collected from i) GPS video camera collars and ii) fecal samples collected from individuals from the Fortymile Caribou Herd

Summer diets are crucial for large herbivores in the subarctic and are affected by weather, harassment from insects and a variety of environmental changes linked to climate. Yet understanding foraging behavior and diet of large herbivores is challenging in the subarctic because of their remote ranges. We used GPS video-camera collars to observe behaviors and summer diets of the migratory Fortymile Caribou Herd (Rangifer tarandus granti) across Alaska, USA and the Yukon, Canada. First, we characterized caribou behavior. Second, we tested if videos could be used to quantify changes in the probability of eating events. Third, we estimated summer diets at the finest taxonomic resolution possible through videos. Finally, we compared summer diet estimates from video collars to microhistological analysis of fecal pellets. We classified 18,134 videos from 30 female caribou over two summers (2018 – 2019). Caribou behaviors included eating (mean = 43.5%), ruminating (25.6%), travelling (14.0%), stationary awake (11.3%) and napping (5.1%). Eating was restricted by insect harassment. We classified forage(s) consumed in 5,549 videos where diet composition (monthly) highlighted a strong tradeoff between lichens and shrubs; shrubs dominated diets in June and July when lichen use declined. We identified 63 species, 70 genus and 33 family groups of summer forages from videos. After adjusting for digestibility, monthly estimates of diet composition were strongly correlated at the scale of the forage functional type (i.e., forage groups comprised of forbs, graminoids, mosses, shrubs, and lichens; r = 0.79, p < 0.01). Using video collars, we identified i) a pronounced tradeoff in summer foraging between lichens and shrubs and ii) the costs of insect harassment on eating. Understanding caribou foraging ecology is needed to plan for their long-term conservation across the circumpolar north and video collars can provide a powerful approach across remote regions.README files attached to each .csv file in the uploaded file set. Funding provided by: U.S. Bureau of Land ManagementCrossref Funder Registry ID: http://dx.doi.org/10.13039/100007149Award Number: Funding provided by: NASA - Arctic Boreal Vulnerability Experiment*Crossref Funder Registry ID: Award Number: NNX15AW71AFunding provided by: National Science Foundation - Navigating the New Arctic*Crossref Funder Registry ID: Award Number: 2127272Funding provided by: Alaska Department of Fish and GameCrossref Funder Registry ID: http://dx.doi.org/10.13039/100008144Award Number: Funding provided by: Yukon Government*Crossref Funder Registry ID: Award Number: Funding provided by: National Park ServiceCrossref Funder Registry ID: http://dx.doi.org/10.13039/100007516Award Number: Funding provided by: University of MontanaCrossref Funder Registry ID: http://dx.doi.org/10.13039/100008524Award Number:This dataset was collected from GPS video-camera collars worn by female caribou of the Fortymile Caribou Herd spanning Alaska, USA and Yukon, Canada