Atlas of Arctic bone modification

Abstract

Skeletal bones and antlers from past generations of wildlife are frequently found and consumed by other animals, living out a second life as an important dietary resource. Such gnawing may leave characteristic modifications, including tooth marks, providing physical evidence of a behavior and nutrient resource that is often challenging to directly observe and quantify. Documenting and interpreting features of bone modification can fill knowledge gaps regarding species' behavioral ecology, nutrient requirements, and interactions in modern ecosystems, as well as in historical, archaeological, and paleontological contexts. While prior research has documented characteristic patterns of bone modification and gnawing for a variety of bone consumers, these studies generally focus on a single species or taxonomic group, with only limited comparison to bone modifications generated by co-occurring groups (i.e., ruminants vs. carnivorans vs. rodents). Cataloging bone modifications at ecosystem scales has rarely been the focus of past work, which may be partially responsible for a profound gap in existing knowledge regarding how co-occurring and competing bone consumers partition this shared source of nutrients (e.g., calcium, phosphorus, and calorie-rich marrow). Here, we compiled available literature on bone modifications made by rodents, ungulates (specifically ruminants), and carnivorans. Using this compilation as a starting point, we characterized the full suite of modifications observed on 1567 shed antlers and 224 skeletal bones collected during standardized bone surveys along the Coastal Plain of the Arctic National Wildlife Refuge (Alaska). In total, we described, summarized, and photographed 27 distinct classes of pits, punctures, scores, furrows and fractures, and, when possible, identified the taxonomic group that is known or likely responsible for each modification class. Seven of these classes, all attributed to ruminants (likely caribou), have not been previously described. Each antler and skeletal bone was then evaluated for occurrences of the 27 modification classes. This dataset provides a resource to evaluate patterns of bone gnawing for multiple taxonomic groups (ruminants, carnivorans, rodents) and to assess resource competition and partitioning among co-occurring species and trophic guilds. A unique strength of this dataset is that it includes the largest assessment of bone modifications on a single skeletal element (antlers), providing unparalleled opportunities to evaluate variability in bone modification across space (~200 km) and through time (antlers can persist on tundra surfaces for hundreds to thousands of years). To provide a visual guide and reference for evaluating bone modification features, including those not observed on the Coastal Plain, we established a photographic atlas of Arctic bone modification classes. This resource characterizes bone modifications generated by ruminants, carnivorans, and rodents, as well as those generated by trampling and other incidental interactions between bones and living animals (e.g., rubbing antlers on rocks or other surfaces while attached to the skull). The broad taxonomic groups included in the Atlas of Arctic Bone Modification are globally common and regularly co-occur, making it a widely relevant interpretational guide. Incorporating assessments of bone modification and consumption can contribute to a more holistic understanding of mammalian dietary ecology and nutrient cycling at the population and community levels. The dataset is released under the Creative Commons Attributional Noncommercial 4.0 Public Domain Dedication. Citation of this publication and the dataset is required when data are reused.