Impacts of Rotational Grazing and Hay Management on the Reproductive Success of Bobolink (Dolichonyx oryzivorus) in Eastern Ontario, Canada

Posted on Dec 5, 2017


by Nicole M. MacDONALD, and Erica NOL

Correspondence: Environmental and Life Sciences, Trent University, Peterborough, Ontario, K9L 0G2, Canada. 



We investigated the impact of beef cattle (Bos taurus) farm management, including rotationally grazed pastures and managed hayfields, on the reproductive success of bobolink (Dolichonyx oryzivorus) in eastern Ontario, Canada. Bobolinks nesting in fields grazed by cattle or cut for hay before 1 July had significantly lower reproductive success than those nesting in untouched fields. Bobolinks did not recolonize or re-nest in paddocks that were grazed early (before 2 June) and followed by a rest period. Bobolink abundance and productivity (based on an index), were lower in managed fields and pastures than in untouched fields and hayfields. As the number of paddocks grazed by a single herd during the nesting season increased, the proportion of paddocks containing bobolinks that reproduced successfully, decreased. We used a clay pigeon target experiment to support our hypothesis that nest loss in paddocks was due to trampling and not predation. With the exception of 1 trial with a low cattle stocking rate, cattle exposure to clay pigeon targets resulted in disturbance of >90% of targets. As with other studies from eastern North America, we conclude that the best method for improving the reproductive success of bobolinks on beef cattle farms is to provide some untouched hayfields and pasture paddocks until nesting is complete. In our study area, bobolinks reproduced successfully on most farm operations that were managed for beef cattle, without incentive programs.

Key Words: Bobolink, Beef Cattle, Eastern Ontario, Farm Management, Reproductive Success.



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