bighorn sheep

Niche Plasticity of Desert Bighorn Sheep in the Trans-Pecos

Elle Sutherland, Justin French, Carlos Gonzalez, Michael Cherry (CKWRI), Froylan Hernandez (TPWD), Shawn Gray (TPWD)

Desert bighorn sheep (Ovis canadensis) have been reestablished in the Trans-Pecos following extirpation in the 1960’s. However, the growth of exotic aoudad (Ammotragus lervia) populations presents a new challenge to desert bighorn management. Aoudad are native to Northern Africa, an arid region with rugged topography. Because of this, aoudad are adapted to similar habitats as desert bighorn. Previous research has demonstrated that even at small population sizes aoudad and desert bighorn exhibit narrow, heavily overlapping niches. It is hypothesized that aoudad are superior competitors, due to their high recruitment rate and robust physiology. What is not currently known are the competitive dynamics within this overlapping niche space and how desert bighorn may shift or compress their niche to avoid competitive exclusion. It is important to understand the extent of desert bighorn niche plasticity in order to determine their potential to coexist with aoudad.

This study aims to explore variation in niche breadth among populations in the Trans-Pecos to determine whether desert bighorn exhibit niche plasticity. Specifically, we will use integrated step selection analyses to model inter-individual habitat selection behavior and assess the niche breadth of populations. To accomplish this, we will utilize 10 years of movement data from 5 desert bighorn populations. By focusing on potential competition induced niche shifts, the results of this study will provide insight on how to manage desert bighorn in a landscape co-occupied with aoudad.

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