Some effects of livestock grazing on amphibians. Draft

Publication Type:

Report

Authors:

Engle, Janice C.

Source:

p.13 pp (unnumbered) (2000)

Call Number:

U00ENG04IDUS

Keywords:

burning vegetation, burning willows, Columbia Spotted Frog, livestock grazing, Rana luteiventris, willows

Abstract:

This draft report summarizes effects of livestock grazing on habitats used by the Columbia spotted frog and other frogs in southwestern Idaho. Diversion of water for livestock causes drying of streambeds, areas frogs use as movement corridors. Habitat fragmentation therefore occurs, accompanied by decreased recolonization of isolated areas by frogs and increased rates of extinction. Compaction of riparian areas by livestock congregation lessens vegetative cover and therefore ground-level humidity. Frogs therefore have less cover and insect prey and are more likely to become prey themselves. In addition, cattle trampling of pond and stream banks could close subterranean passageways to frogs’ preferred hibernation sites. In addition, nutrient-rich waters, as created by organic matter deposited by cattle, are reduced in oxygen content and therefore not suitable for hibernation. Exposed soils caused by overgrazing of livestock and their trampling result in increased water runoff, decreased water-storage capacity, reduced water filtration, and reduced deposition of the sediment that is necessary to build streambanks, wet meadows, and floodplains. Increased water velocity means a loss in frog breeding sites as stiller-water areas for egg deposition cease to exist. In southwestern Idaho, willows are frequently burned to increase vegetative production for livestock. They provide migratory paths for frogs that could not hibernate near natal breeding sites. The report gives examples too of results to habitat, and therefore the frogs living there, from a development for water troughs and of an instance of livestock trampling a beaver dam. These areas and unprotected ponds are also compared with a pond that was fenced to exclude livestock from a known hibernaculum; photos are included to illustrate. The study occurred in years when precipitation decreased, promoting the realization that grazing plans on public lands often are not changed to accommodate or ameliorate the habitat problems that occur during periods of reduced water availability.