Herbivory by resident geese: the loss and recovery of wild rice along the tidal Patuxent River

Published source details Haramis G.M. & Kearns G.D. (2007) Herbivory by resident geese: the loss and recovery of wild rice along the tidal Patuxent River. Journal of Wildlife Management, 71, 788-794.
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This study is summarised as evidence for the following.

	Action	Category
	Exclude wild vertebrates: freshwater marshes Action Link

Exclude wild vertebrates: freshwater marshes

A replicated, paired, controlled study in 1999 in a tidal freshwater marsh in Maryland, USA (Haramis & Kearns 2007) found that plots from which large vertebrates were excluded developed a greater density of wild rice Zizania aquatica than exposed plots. After one growing season, exclusion plots contained more wild rice plants on average (97 plants/m²; 105 flowering stalks/m²) than adjacent open plots (3 plants/m²; 0 flowering stalks/m²). The mesh size of exclosures had no significant effect on the density of wild rice plants or flowering stalks, plots enclosed by a smaller mesh supported taller and thicker wild rice shoots (see original paper for data; height and stem diameter only reported for exclosures). Methods: In April 1999, twenty-four 1-m² plots were established (in six sets of four) in a marsh with naturally germinating wild rice. Eighteen of the plots (three plots/set) were fenced with 1.5-m-tall wire mesh to exclude vertebrates (birds, mammals, large turtles and fish). Six fences (one plot/set) had each of three mesh sizes: small (1.3 x 1.3 cm), medium (2.5 x 2.5 cm) or large (5.1 x 10.2 cm). The other six plots (one plot/set) were left open to all animals. The study reported intense grazing by Canada geese Branta canadensis in these open plots, and that sediment was trapped by the fences (especially those with small mesh). After one growing season, all rice plants were counted in each plot and 10 rice plants/plot were measured.

(Summarised by: Nigel Taylor)