Effect of Grazing by Canada Geese on the Winter Growth of Rye

Abstract

Canada geese (Branta canadensis) often graze during the fall and winter in fields of rye that are planted as cover crops to reduce soil erosion and improve soil qualities. I used exclosures to document whether grazing by Canada geese had an adverse impact on rye. In 11 Connecticut fields frequented by geese, the leaf biomass of rye by mid-winter was 535% higher inside exclosures than in grazed portions of the same fields. By spring, rye leaf biomass was 177% higher inside than outside of the exclosures. In another experiment, rye was clipped to simulate grazing by Canada geese to determine whether leaf loss slowed the rye plants' growth during winter and spring. Plants that suffered leaf loss had lower total biomass, leaf and stem biomass, and root biomass than uninjured plants regardless of time during fall and winter when the leaves were clipped. Plants receiving multiple clippings grew slower than those receiving only a single clipping. J. WILDL. MANAGE. 52(1):76-80 Canada geese often graze during the fall and winter in grain fields. The damage they cause by grazing and trampling plants can be substantial (Hunt 1984). The damage, however, may be less than initial appearances suggest because of the growing plants' ability to compensate for damage. Pirnie (1954) was unable to document any loss in wheat yields caused by grazing by Canada geese on dormant wheat plants in Michigan, and Allen et al. (1985) reported losses ?13% in Maryland. Clark and Jarvis (1978) observed no difference in seed production between ryegrass plots which had been grazed by Canada geese and those which had not. In contrast, Kahl and Samson (1984) allowed captive Canada geese to graze on wheat, and in some cases heavy grazing resulted in shorter plants and lower grain yields. Tests with other goose species have not demonstrated that grazing by geese has an adverse impact on the plants. Kear (1963b) noted that grazing on winter oats and winter wheat by a captive flock of graylag (Anser anser) and pinkfooted geese (A. brachyrhynchus) had no effect on grain or straw yields at harvest time. Clipping to simulate goose damage on winter wheat and silage grass also had no effect on harvest yields (Kear 1963b). Cargill and Jefferies (1984) showed that grazing by lesser snow geese (A. caerulescens caerulescens) in a sub-arctic salt marsh incre sed primary production of a stoloniferous grass (Puccinellia phryganodes) and a sedge (Carex subspathacea), possibly by accelerating nitrogen cycling in the marsh. In many parts of North America rye is grown in fields during winter as a cover crop for soil This content downloaded from 207.46.13.101 on Sat, 08 Oct 2016 04:13:19 UTC All use subject to http://about.jstor.org/terms J. Wildl. Manage. 52(1):1988 CANADA GOOSE GRAZING ON RYE * Conover 77 management. The leaves and stems of the cover crop can reduce wind-borne soil erosion by reducing wind velocity at the ground surface (Kohnke and Bertrand 1959), and water-borne soil erosion by intercepting rain drops before they hit the soil (Bennett 1939, Kohnke and Bertrand 1959). The roots reduce erosion by holding the soil (Kohnke and Bertrand 1959). Because rye is usually plowed under, it can maintain or increase the amount of organic matter in the soil (Tisdale and Nelson 1956, Thompson and Kelly 1957, Cook 1962). Rye can also help conserve soluble plant nutrients, especially nitrates. Unless there are growing plants present to absorb them, some of these nutrients will be lost during fall and winter by leaching (Tisdale and Nelson 1956, Cook 1962). Because Canada geese often graze in rye fields during the fall and winter, they may be damaging the rye, thus reducing its beneficial qualities. Unfortunately, little information is available about whether this is a problem or if rye can compensate for any damage inflicted by geese. In this experiment I used exclosures to document whether grazing by Canada geese had an adverse impact on rye in Connecticut fields. I also evaluated the ability of rye plants to compensate for damage by recording the growth of rye biomass following simulated grazing at different intensities and at different times of the