Mesquite Pod Removal by Cattle, Feral Hogs, and Native Herbivores

The dispersal of woody plant seeds by livestock has been implicated as one of the causes of woody plant encroachment in semiarid ecosystems worldwide. In the southern Great Plains, United States, cattle are suspected to have increased encroachment of the woody legume honey mesquite (Prosopis glandulosa Torr.) because they are effective consumers of mesquite pods and pass viable seed from those pods through their digestive systems. Since other animal species also consume or gather mesquite pods and seeds, our objective was to compare the removal of mesquite pods by cattle, other vertebrate herbivores, and insects. Mature pods were collected from trees in late summer and placed within each level of a hierarchical exclusion design using fences and cages that blocked cattle; other large vertebrates (deer, feral hogs); smaller vertebrates (rabbits, birds, rodents); and insects at replicate sites in north and south Texas locations. Pod removal was quantified during 60-d trials in the fall of each of 3 yr. The treatment that allowed cattle to have access to pods had the greatest or tied for the greatest pod removal at trial end in all trials. Final pod removal in the feral hog and white-tailed deer treatments was numerically lower but statistically similar (P ≤ 0.05) to cattle. However, the rate of pod removal during the first 20 d in several of the trials was greatest (P ≤ 0.05) in the cattle treatment at both locations. Pod removal by rodents was high in 1 yr at both locations, which we attributed to high growing season precipitation at both locations during that year. Results may have implications regarding seed-centric grazing management decisions and keeping cattle out of pastures when mesquite pods are abundantly present on the ground.