Use of grazed and non-grazed fields by wintering sandhill cranes and nesting dabbling ducks

Graduation Date

1999

Document Type

Thesis

Program

Other

Program

Thesis (M.S.)--Humboldt State University, Natural Resources: Wildlife, 1999

Committee Chair Name

Todd Arnold

Committee Chair Affiliation

HSU Faculty or Staff

Keywords

Humboldt State University -- Theses -- Wildlife Management, Rotational grazing, Merced County, Sandhill cranes, California, Waterfowl habitat, Dabbling ducks

Abstract

Wintering geese and sandhill cranes (Gros canadensis) prefer feeding in short sparse vegetation, whereas breeding dabbling ducks prefer nesting in tall dense vegetation. I examined whether these two contrasting objectives could be met in uplands managed with rotational grazing in Merced County, California. I divided four 10-14 ha non-grazed pastures in half and each half was randomly assigned for rotational grazing between 1 July and 1 November, 1995 and 1996. I monitored the use of fields by wintering cranes and geese from September through February in 1995-96 and 1996-97, and waterfowl nesting from March through July in 1996 and 1997. Cranes were more abundant in grazed fields during the first winter and in non-grazed fields during the second winter, but these trends were not significant (F = 3.16, 1 df, P = 0.13). However, more cranes fed in grazed fields than in non-grazed fields (F = 5.23, 1 df, P = 0.056). Small flocks of geese were observed seven times: four times in grazed fields and three times in non-grazed fields. Duck nest densities were higher in grazed than in non-grazed fields in 1996 (F = 46.32, 1 df, P = 0.006), but not in 1997 (F = 0.61, 1 df, P = 0.49). Nest success estimates were higher in grazed versus non-grazed fields (1996: 20.2 vs. 8.0%, 1997: 4.5 vs. 1.4%, 1996-97: 15.8 vs. 4.2%), but only the pooled data were significant (Z = 1.10, P = 0.27; Z = 0.71, P = 0.48; Z = 1.76, P = 0.08; respectively). Rotational grazing appeared to be successful in providing both winter foraging habitat for sandhill cranes and summer nesting habitat for dabbling ducks, and could be an effective management technique on public and private lands in the Central Valley.

https://scholarworks.calstate.edu/concern/theses/zs25xb86r

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