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ARS Home » Plains Area » Sidney, Montana » Northern Plains Agricultural Research Laboratory » Pest Management Research » Research » Publications at this Location » Publication #396596

Research Project: Biological Control and Habitat Restoration for Invasive Weed Management

Location: Pest Management Research

Title: Bat guano isotope systems (d13C, d15N, and d2H) integrate environmental, climatic, and ecological signals

item TSALICKIS, ALEXANDRA - Auburn University
item WATERS, MATTHEW - Auburn University
item Campbell, Joshua

Submitted to: Quaternary Science Reviews
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 5/3/2024
Publication Date: 5/17/2024
Citation: Tsalickis, A., Waters, M.N., Campbell, J.W. 2024. Bat guano isotope systems (d13C, d15N, and d2H) integrate environmental, climatic, and ecological signals. Quaternary Science Reviews.

Interpretive Summary: Bat guano can provide a unique way to examine past climate and vegetation records for areas that do not have other traditional means (e.g., tree rings, sediment cores). We examined a bat guano core collected from a cave in Alabama, USA for nitrogen and carbon isotopes. Our core was ~12,000 years old. Carbon isotopes showed an increase in grass abundance towards modern times which was probably related to increased agricultural output and land-use change. Additionally, nitrogen isotopes remained relatively stable until more recent time periods. Although interpretation of nitrogen isotopes in bat guano is still its infancy, changes in nitrogen stable isotopes were related to various anthropogenic activities. Our bat guano data supports the notion that this type of paleoclimate proxy could be a useful tool for unraveling past climates in areas that other proxies are unavailable.

Technical Abstract: Bat guano core records have gained awareness for use as a proxy in paleohydroclimate studies, but additional bat guano studies are needed to develop guano interpretations for additional paleoenvironmental analysis. Guano core records can provide novel environmental data most notably when other tools (speleothems, tree ring cores, etc.) are not available. Most stable isotopes (d15N and d13C) measured in guano cores have been used to reconstruct past vegetation and hydrologic changes. Here, we analyzed a guano core collected from Cave Springs Cave in Alabama, USA for d15N and d13C isotope values from 12,000 cal yr BP to present. Degradation and diagenesis of nitrogen were found to have occurred in the bat guano core, however, the paleoenvironmental record is still considered reliable due to a recalcitrant fraction and the stability of d15N over an 8,000 kyr period. We attribute changes in d15N to linked to biogeochemical dynamics and anthropogenic activities while changes in d13C values indicate disturbance that occurred to the landscape most likely due to agricultural practices. We posit that increased d13C indicates the increasing abundance of C4 grasses which coincides with increasing human population sizes and disturbance during the past 1,000 years.