Study

Integrated damage management reduces grazing of wild rice by resident Canada geese in New Jersey

  • Published source details Nichols T.C. (2014) Integrated damage management reduces grazing of wild rice by resident Canada geese in New Jersey. Wildlife Society Bulletin, 38, 229-236.

Actions

This study is summarised as evidence for the following.

Action Category

Control populations of wild vertebrates: freshwater marshes

Action Link
Marsh and Swamp Conservation

Exclude wild vertebrates: freshwater marshes

Action Link
Marsh and Swamp Conservation
  1. Control populations of wild vertebrates: freshwater marshes

    A paired, controlled, before-and-after study in 2000–2002 in tidal freshwater marshes along a river in New Jersey, USA (Nichols 2014) reported that killing and scaring Canada geese Branta canadensis reduced their impacts on wild rice Zizania aquatica density and height. In the autumn before intervention, plots exposed to goose herbivory contained only 15 wild rice plants/m2, with an average height of 200 cm. Additional plots from which geese were excluded contained 70 plants/m2, with an average height of 241 cm. In two of two autumns following goose control, the density of rice plants was statistically similar in open and exclusion plots (open: 55–58 plants/m2; exclusion: 60–68 plants/m2). Rice plants were still shorter in open than exclusion plots after one year of goose control (open: 281 cm; exclusion: 298 cm) but this difference was no longer significant after the second year of goose control (open: 212 cm; exclusion: 208 cm). Methods: In April–June 2001 and 2002, geese were controlled along the lower Maurice River by killing adults (shooting and capturing then euthanizing with carbon dioxide), scaring adults (with pyrotechnics) and puncturing eggs. The study marshes supported 0–17 goslings and 37–83 moulting geese in control years (vs 43 goslings and 250 moulting geese in pre-control years). Wild rice was surveyed each autumn 2000–2002, in 17–22 pairs of 1-m2 plots. In each pair, one plot was open to geese whilst the other had been fenced (to exclude geese) since April. In each plot, all rice plants were counted and 10 rice plants were measured.

    (Summarised by: Nigel Taylor)

  2. Exclude wild vertebrates: freshwater marshes

    A replicated, paired, controlled study in 2000–2002 in tidal, freshwater marshes along a river in New Jersey, USA (Nichols 2014) reported that plots fenced to exclude Canada geese Branta canadensis contained more, taller wild rice Zizania aquatica plants than plots exposed to intense goose grazing, although these effects typically disappeared after geese were controlled. In the first year of the study, with a large and uncontrolled goose population, wild rice plants were more abundant and taller in goose exclosures (70 plants/m2, 241 cm tall) than in plots open to geese (15 plants/m2, 200 cm tall). In the following two years, when the goose population was controlled, differences between exclosure and open plots were typically eliminated (and if not, reduced in magnitude). Exclosure and open plots contained a statistically similar density of wild rice in two of two years with goose control (fenced: 60–68 plants/m2; open: 55–58 plants/m2), and contained wild rice of a statistically similar height in one of two years with goose control (for which fenced: 208 cm; open: 212 cm). Methods: Each April between 2000 and 2002, 17–22 pairs of 1-m2 plots were established on tidal freshwater marshes along the lower Maurice River. In each pair, one plot was fenced to exclude geese (5–10 cm wire mesh, 1.5 m high) whilst the other was left open. In 2001 and 2002, the local goose population was reduced by killing and scaring. Wild rice was counted (all plants in each plot) and measured (10 plants in centre of each plot) in autumn each year.

    (Summarised by: Nigel Taylor)

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