Get reliable rangeland science

The southwestern willow flycatcher (Empidonax traillii extimus) is an endangered subspecies distributed throughout riparian forests of the southwestern United States.� Many factors, including improper livestock grazing practices, have been implicated in the decline of this species.� Our goal of this study is to determine the effects of time-controlled, livestock grazing on vegetation characteristics important to the habitat of southwestern willow flycatchers in west-central Arizona.� Currently, livestock grazing is only allowed outside of the growing season in areas delineated as critical habitat by USFWS, and NRCS (through their Working Lands for Wildlife Initiative) is anxious to help ranch operators and landowners develop sustainable practices in these areas.� Beginning in summer 2015, we began conducting vegetation surveys on two cattle ranches in west-central Arizona, measuring vegetation attributes during three sampling periods: before livestock grazing, after livestock grazing, and at the end of the growing season. �We measured: 1) species composition for main herbaceous and woody plants, 2) woody canopy cover, 3) utilization of woody and herbaceous plants, 4) density of woody seedlings, and 5) volume of non-seedling woody plants.� Preliminary data indicate that species composition and cover were relatively stable across most sampling periods.� Time-controlled livestock grazing up to a maximum of 12 days resulted in very low utilization rates of <12% for both herbaceous and woody plants across all sampling periods. �Herbivory by livestock and wildlife, and episodic precipitation events likely contributed to considerable fluctuations observed in woody seedling density.