A group of researchers has found that aoudad—a member of the sheep and goat family—can contract and transmit numerous respiratory pathogens that also affect desert bighorn sheep, a species native to Texas that often inhabits the same areas as aoudad.
A group of researchers from the Texas A&M College of Veterinary Medicine and Biomedical Sciences (VMBS) has uncovered that aoudad, part of the sheep and goat family, can acquire and spread various respiratory pathogens that impact desert bighorn sheep, a Texas-native species that frequently shares its environment with aoudad.
This recent study, published in PLOS ONE, aims to aid wildlife conservationists in comprehending the intricate interactions between these two species and foster effective management strategies for both. The project received funding from the Wild Sheep Foundation as well as backing from the Texas Parks & Wildlife Department.
Aoudad, pronounced “AH-dad,” are originally from North Africa and were introduced to Texas in the late 1950s primarily for hunting purposes. Experts estimate that there may be around 40,000 aoudad currently residing in Texas.
“Research on disease transmission between Texas aoudad and native species like bighorn sheep is limited, making it challenging for wildlife professionals to track diseases and protect these animal populations,” explained Dr. Logan Thomas, an assistant professor at Kansas State University and a former postdoctoral researcher working with Dr. Walter Cook, a clinical associate professor in the VMBS’ Department of Veterinary Pathobiology.
“By assessing disease exposure in both species, we can begin to understand how they might influence one another,” he stated. “Our analysis of samples from both species revealed that they can carry and transmit the same respiratory diseases.”
It Takes Two
Both aoudad and bighorn sheep play crucial roles in Texas wildlife conservation and contribute to the state’s economy. In West Texas, both species are popular game animals, and some landowners generate significant income by charging hunters to access their land.
“Aoudad are especially valuable for the hunting industry,” Thomas noted. “As a non-native species, they don’t have seasonal or bag limits, making them appealing to hunters.”
While bighorn sheep are also sought-after by hunters, they require significant management in Texas to maintain stable population numbers.
The respiratory illnesses, including pneumonia, that can be shared between the two species have already devastated bighorn populations, leading to concerns about the potential impact on aoudad as well as the further decline of bighorns.
“When outbreaks occur in bighorn sheep, we typically observe two waves of population decline,” Thomas shared. “The initial outbreak causes a decline across all age groups. Then, when lambs are born, many don’t survive because they lack the immune response that older bighorns have due to previous exposure.”
Adding to the challenge, some adult bighorns may carry the disease for several years after an outbreak, meaning the population might struggle to recover.
“We have understood this cycle in bighorn sheep for some time, but no one had investigated whether aoudad are similarly affected or if the two species could transmit these pathogens between each other,” he said. “While we don’t believe it will significantly impact aoudad’s health, we are eager to learn more as our research continues.”
Keeping A Close Watch
With the confirmation that aoudad can harbor the same respiratory pathogens as bighorn sheep, wildlife experts can now begin monitoring disease transmission within and among these populations.
“Given prior findings related to this group of diseases, it’s also possible they could spread to mule deer, which adds another layer of complexity,” Thomas mentioned. “We’re very interested in examining that possibility, as well as the impact of these diseases on aoudad, since they haven’t been studied as extensively as native species.”
“Ultimately, our goal is for all these animal populations to flourish within a well-managed environment in Texas,” Thomas concluded. “Monitoring diseases is one approach we can use to help achieve that.”
