Resource selection of a nomadic ungulate in a dynamic landscape

PLoS One. 2021 Feb 12;16(2):e0246809. doi: 10.1371/journal.pone.0246809. eCollection 2021.

Abstract

Nomadic movements are often a consequence of unpredictable resource dynamics. However, how nomadic ungulates select dynamic resources is still understudied. Here we examined resource selection of nomadic Mongolian gazelles (Procapra gutturosa) in the Eastern Steppe of Mongolia. We used daily GPS locations of 33 gazelles tracked up to 3.5 years. We examined selection for forage during the growing season using the Normalized Difference Vegetation Index (NDVI). In winter we examined selection for snow cover which mediates access to forage and drinking water. We studied selection at the population level using resource selection functions (RSFs) as well as on the individual level using step-selection functions (SSFs) at varying spatio-temporal scales from 1 to 10 days. Results from the population and the individual level analyses differed. At the population level we found selection for higher than average NDVI during the growing season. This may indicate selection for areas with more forage cover within the arid steppe landscape. In winter, gazelles selected for intermediate snow cover, which may indicate preference for areas which offer some snow for hydration but not so much as to hinder movement. At the individual level, in both seasons and across scales, we were not able to detect selection in the majority of individuals, but selection was similar to that seen in the RSFs for those individuals showing selection. Difficulty in finding selection with SSFs may indicate that Mongolian gazelles are using a random search strategy to find forage in a landscape with large, homogeneous areas of vegetation. The combination of random searches and landscape characteristics could therefore obscure results at the fine scale of SSFs. The significant results on the broader scale used for the population level RSF highlight that, although individuals show uncoordinated movement trajectories, they ultimately select for similar vegetation and snow cover.

Publication types

  • Research Support, Non-U.S. Gov't
  • Research Support, U.S. Gov't, Non-P.H.S.

MeSH terms

  • Animal Migration / physiology*
  • Animals
  • Antelopes / physiology*
  • Ecosystem
  • Models, Biological
  • Mongolia

Grants and funding

TSMS was funded by the MainCampus Stipendium der Stiftung Polytechnischen Gesellschaft Frankfurt am Main. TSMS, TM, and ND were funded by the Robert Bosch Foundation. TSMS, TM, and ND were funded by the German Federal Ministry of Education and Research (BMBF, 01LC1710A and 01LC1820A). JMC was partially funded by the Center of Advanced Systems Understanding (CASUS) which is financed by Germany’s Federal Ministry of Education and Research (BMBF) and by the Saxon Ministry for Science, Culture and Tourism (SMWK) with tax funds on the basis of the budget approved by the Saxon State Parliament. JMC, CHF, and WFF were supported by NSF Grant IIBR 1915347. The funders had no role in study design, data collection and analysis, decision to publish, or preparation of the manuscript.