T216 Conservation Paleobiology and Species Invasions II: Impacts of Biogeographic Shifts and Changing Community Structure in the Past and Present

Tuesday, 24 September 2024
1:30 PM - 5:30 PM
204C

HIGH ELEVATION BISON IN THE ROCKY MOUNTAIN FRONT RANGE DURING THE LATE HOLOCENE

Paper number: T216-5
Program: Technical Sessions
Time: 2:20 PM – 2:35 PM

Authors

Abstract

Despite their shallow time depth, many Holocene ecosystems remain poorly understood. Non-analog behaviors, biogeographic shifts, and unclear anthropogenic impacts characterize the recent history of many large vertebrates, even those with well-characterized extant populations. The American Bison (Bison bison) is a keystone herbivore in modern grasslands. It enjoys an abundant and widespread fossil record. Its Holocene niche was extremely broad, including ecosystems and behaviors that no longer characterize modern herds. Bison are also important to regional economies, tribal identities, and conservation efforts making them a prime target for conservation paleobiology approaches.

During the late Holocene, large bison herds occurred in grass-dominated ecological zones across much of the North American mid-continent. However, in situ fossils and historic accounts illustrate the adaptability of bison to a broad ecological niche space, from grassy prairies and plains to eastern forests. Yet, few modern bison are found at high elevations. This research, spurred by the discovery of bison remains at >3000m in the front range of the Rocky Mountains, explores how bison used these landscapes through the lens of horn (keratin), bone and tooth (enamel) stable isotope systems (C, N, O, Sr).

Bison horn keratin was sampled in seven, late Holocene individuals for δ13C, δ15N, and δ18O to understand life history trends. Oxygen isotopes exhibit up to 8‰ periodicity. Changes in δ15N, occasionally in concert with δ18O from the same samples, are interpreted to represent movement from lower elevation grassland environments (high microbial activity) to high elevation ridge lines with herbaceous vegetations (low microbial activity).

Results of serial tooth enamel samples (δ13C, δ18O, and 87Sr/86Sr) from seven nearby bison molars also reflect diet and mobility patterns. Enamel 87Sr/86Sr suggests four of these acquired forage >10km from the location where they were recovered.

Geological Society of America Abstracts with Programs. Vol. 56, No. 5

doi: 10.1130/abs/2024AM-405312

© Copyright 2024 The Geological Society of America (GSA), all rights reserved. Permission is hereby granted to the author(s) of this abstract to reproduce and distribute it freely, for noncommercial purposes. Permission is hereby granted to any individual scientist to download a single copy of this electronic file and reproduce up to 20 paper copies for noncommercial purposes advancing science and education, including classroom use, providing all reproductions include the complete content shown here, including the author information. All other forms of reproduction and/or transmittal are prohibited without written permission from GSA Copyright Permissions.