Why are scientists concerned about the effects of non-native horses and burros on natural ecosystems?

Worldwide, introduced non-native herbivores have the potential to threaten native ecosystems. For example, in western North America, uncontrolled numbers of feral horses and burros are threatening natural habitats and the native wildlife that rely on them. New research published in the wildlife research journal Wildlife Monographs documents the impact that non-native burros are having on plant and animal life in the Sonoran Desert of North America.

Investigators found that the presence of burros was associated with changes to long-lived plants important to the region. In areas with established burro herds, researchers documented lower ground cover, plant density, and foliage density, as well as smaller plant size in several species. Of particular concern was that some differences were observed among “nurse plants” that protect young plants of numerous other species from harsh conditions, and that the Sonoran Desert’s iconic saguaro cactus was observed to have lower recruitment (fewer new saguaros added to the population) in areas with burros. The study also found lower abundance in some native wildlife species.

“Our study has relevance to other ecosystems where large non-native herbivores have become established,” said corresponding author Esther Rubin, PhD, of the Arizona Game and Fish Department. “In the Sonoran Desert, the current management of this feral equid may not be adequate for maintaining the long-term viability of this arid and fragile ecosystem.”

URL upon publication: https://onlinelibrary.wiley.com/doi/10.1002/wmon.1083

Additional Information
NOTE: The information contained in this release is protected by copyright. Please include journal attribution in all coverage. For more information or to obtain a PDF of any study, please contact: Sara Henning-Stout, newsroom@wiley.com.

About the Journal
Wildlife Monographs focuses on comprehensive syntheses of topics in wildlife science, management, and conservation. Research topics include wildlife biology and ecology, habitat use, demographics, genetics, behavior, quantitative analyses, and more areas relevant to wildlife management and conservation. Our emphasis is on aligning research with contemporary conservation and management issues and informing practitioners. We welcome extensive reviews, meta-analyses, interdisciplinary studies, and special topics. Wildlife Monographs is a journal by The Wildlife Society.

About Wiley
Wiley is a knowledge company and a global leader in research, publishing, and knowledge solutions. Dedicated to the creation and application of knowledge, Wiley serves the world’s researchers, learners, innovators, and leaders, helping them achieve their goals and solve the world's most important challenges. For more than two centuries, Wiley has been delivering on its timeless mission to unlock human potential. Visit us at Wiley.com. Follow us on Facebook, Twitter, LinkedIn and Instagram.