Movement drives population dynamics of one of the most mobile ungulates on Earth: Insights from a mechanistic model

Abstract

Long‐distance movements are hypothesized to positively influence population size and stability of mobile species. We tested this hypothesis with a novel modeling approach in which moving herbivores interact with the environment created by a dynamic global vegetation model using highly mobile Mongolian gazelles in the eastern Mongolian grasslands as a case study. Gazelle population dynamics were modeled from 1901 to 2018 under two scenarios, one allowing free movement and one restricting movement. Gazelles were 2.2 times more abundant when they could move freely and were extirpated in 71% of the study area when mobility was restricted. Mobility resulted in greater population increases during times of abundant forage and smaller population decreases during drought. Reduced thermoregulatory costs associated with climate change, combined with an increase in vegetation biomass, increased gazelle abundance. Since high abundances often resulted in overgrazing and, thus, extirpation when movement was restricted, mobility had an important role in maintaining higher densities. The novel modeling approach shows how accounting for not just herbivore but also plant ecophysiology can improve our understanding of the population dynamics of highly mobile herbivores, in particular when examining the effects of habitat and climate change. Since the model simulates herbivores based on general physiological mechanisms that apply across large herbivores and the vegetation model can be applied globally, it is possible to adapt the model to other large‐herbivore systems.

From isolation to integration: assessing habitat connectivity of the endangered saiga antelope in Mongolia

“…isolate saiga population, leading to reduced genetic diversity, increased vulnerability to environmental stochasticity, and limited access to crucial resources (Keyghobadi 2007; Holdo et al 2011; Ito et al 2013; Rey-Iglesia et al 2022). Moreover, fragmented habitats hinder the saiga's ability to respond and adapt to climate change via recolonization of their historical ranges, making them more susceptible to extinction risks(Stratmann et al 2023). Maintaining functional connectivity between the saiga core habitats is therefore essential to ensure their survival.…”