The impacts of redhead (Aythya americana) grazing in the shoalgrass (Halodule wrightii) habitat, of the Laguna Madre in Texas, were measured in this study. Redhead grazing did not affect root biomass, but decreased the number of ramets and rhizome biomass in shoalgrass habitat, especially in heavily grazed areas. About half of the grazed sites recovered from goose grazing by the following winter, however, sites that were heavily grazed beyond a minimum threshold of rhizome biomass required more than one season for recovery. Compared to the exclosure, soil nitrogen was greater in areas where redheads were present due to fecal deposition, which may have enhanced plant recovery in these areas. The results of the study indicate that redheads can significantly impact shoalgrass habitat, especially when grazing is heavy. Therefore, the authors suggest that conserving shoalgrass habitat should be a priority, as redhead populations are increasing and these birds will require more winter habitat in the future.
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