Stable Isotope Evidence Shows Key Farmland Structure Features Driving Eastern Wild Turkey Food Selection
2017
Otieno, Erick Nickson | Frenette, Laurent
The Eastern Wild Turkey Meleagris gallopavo silvestris has long been regarded as a corn pest, but with little tangible evidence although it is occasionally sighted consuming pieces of corn left on the ground, or corn is often found in its crop after slaughter. To test the corn pest paradigm, land cover characterization, turkey dispersal assessment and analyses of δ¹³C and δ¹⁵N isotopes were used to evaluate the relative influence of major land cover features on the species' assemblage and corn consumption rate across an intensively farmed region in south-east Quebec, where croplands are dominated by corn fields. Mean numbers of turkeys encountered were highest in regions with a greater mix of forest, cropland and open space matrices, and particularly higher crop-field cover and proximity to water bodies. However, the contribution of corn in the turkey diet was primarily correlated with forest cover rather than with overall crop-field size, suggesting that corn was not the primary attractant. Areas with extensive road networks also supported high rates of corn consumption, indicating that true corn pests use these to raid cornfields and leave remnants that turkeys then consume. Adult turkeys predominantly consume plant food sources, particularly C₃ plants, while juveniles mostly consume invertebrates, several of which constitute crop pests. Conclusively, corn constituted only an opportunistic and supplementary component of turkey diet, especially where cornfields neighboured forests. Furthermore, turkey foraging flocks may in fact collectively serve as significant suppressors of crop pests across agricultural landscapes, rather than being corn depredators.
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