Effects of rotational grazing on nesting ducks in California
Published source details
Carroll L.C., Arnold T.W. & Beam J.A. (2007) Effects of rotational grazing on nesting ducks in California. The Journal of Wildlife Management, 71, 902-905.
Published source details Carroll L.C., Arnold T.W. & Beam J.A. (2007) Effects of rotational grazing on nesting ducks in California. The Journal of Wildlife Management, 71, 902-905.
This study is summarised as evidence for the following.
Employ grazing in artificial grasslands/pasturesAction Link
Other biodiversity: Use grazers to manage vegetationAction Link
Employ grazing in artificial grasslands/pastures
A randomised, replicated controlled study in upland fields sown with a grass-legume mix at Los Banos Wildlife Area, California, USA (Carroll et al. 2007), found that dabbling ducks Anas spp. nested at higher densities in four grazed plots than four ungrazed plots in 1996 (2.2 nests/ha vs. 0.6/ha) but not 1997 (0.7/ha vs. ungrazed 0.4/ha). Nest success estimates did not significantly differ between grazed (5%) and ungrazed (3%) fields. In 1994, four 10-14 ha upland fields were seeded with a grass-legume mix. In 1995, each was divided in half by electric fencing and randomly assigned to rotational grazing (1 July-1 November) or ungrazed. Grazed fields had shorter vegetation than ungrazed fields through the winter, but by the start of the nesting season (late March) vegetation height did not differ. By the end of the nesting season (late May) grazed fields had taller vegetation.
Other biodiversity: Use grazers to manage vegetation
A replicated, randomized, controlled study in 1995–1997 in pastures in central California, USA, found that more dabbling ducks Anas sp. nested in rotationally grazed fields, compared to ungrazed fields, in one of two years. Birds: Nesting densities were higher in grazed fields, compared to ungrazed fields in 1996 (2.2 nests/ha vs 0.6, 4 replicates) but not in 1997 (0.7 vs 0.4). Nest success did not differ between grazed and ungrazed fields (5% success vs 3%). Methods: Half of each field (10–14 ha) was grazed by 70 cows and calves for 7–15 days at a time in July–November 1995–1996, after the duck nesting period. Fields were also mown at various times outside the nesting period to control milk thistles Silybum marianum and star thistles Centaurea solstitialis.