Steven addresses concerns about Texas bighorn sheep in light of exotic and invasive species introductions within the bighorn’s native range.

• Bighorn sheep are what biologists call an “indicator species” – one whose presence, absence or abundance is reflective of a larger environmental trend.
• After years of declining numbers resulting from unregulated hunting and disease, Texas bighorns have rebounded to their pre-settlement population levels.
• Bighorns are threatened by the introduction of the exotic and invasive Aoudad sheep. Aoudad sheep compete with bighorns for habitat and risk transmitting viral and bacterial pathogens foreign to bighorn immune systems.
• The greatest limiting factor in bighorn recovery, however, is disease transmission from domestic sheep and goats.
• In order for Texas bighorn populations to remain robust, management practices must eliminate contact between bighorns and domestic sheep and goats and strictly manage Aoudad numbers.

Wild sheep populations in Texas may be recovering, but herds across the West continue to dwindle due to factors such as disease transmission and climate change.