Case Studies: Mob Grazing on Jeffery Island

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Mob Grazing on Jeffery Island, Nebraska by Mae Rose Petrehn, Holistic Management Certified Educator

Jeffrey Island Habitat Area (JIHA) is a sandy riparian area with a mixture of upland grasslands and some timber within a channel of the Platte River.

The JIHA saw the incidence of thistles in monitored plots go from almost 50% of plant species in 2006, to only 13% in 2009.  They also documented over 109 bird species on the island.  2010 musk thistle count in sample areas was 2 plants.

The island is owned by the Nebraska Public Power and Irrigation District.  The U.S. Fish and Wildlife Service (USFWS) deemed the area part of critical habitat for cranes migrating north to Canada, Alaska, and Siberia. Past management of JIHA had encouraged the growth of thick musk thistle, cheat grass, and hemp.  Traditional management attempts to eradicate these species were unsuccessful and expensive.  JIHA decided to hire Chad Peterson, of Newport, Neb. to use the tool of grazing and animal impact to increase native grass cover and improve wildlife habitat.  Chad had gained a reputation using mob grazing to change vegetative landscapes. Their work began and Chad and manager Alex Milbach adapted to the changes in vegetation from year to year using different species and classes of livestock.  Goats were used initially, in combination with cow/calf pairs, due to their ability to target species mentioned above, but also leafy spurge, salt cedar, eastern red cedar, and common mullein. Once these species were controlled by perfecting the timing and intensity of the grazing program, stockers were used because of Milbach’s observation that they tend to stick closer together as they graze, allowing for more animal impact. Animal impact, as practiced on the JIHA, allows some plants to be severely grazed and others to be trampled. The combination of these two actions opens even a dense grassland canopy to light, but also allows litter to cover bare ground and, in the right conditions over time, be absorbed into the soil as organic matter.

“I have seen the complete transformation of not only the physical landscape, but also the attitude of the managers involved in making decisions about the area due to the improvements on the land from well- managed, high stock density grazing.”

-Ken Arden, Assistant Real Estate Administrator

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