A three year study on 394 acres of hayfields revealed an overall reduction in hen mortality of 38 percent through the use of flushing bars. This was significant at the .01 probability level. For the individual years, only 1954 showed a significant reduction in hayfield mortality, the observed 54 percent decrease being significant at the .05 probability level. The bars were most effective in flushing hens that were in the hay hut not sitting on the nest at the instant before the mower passed. A large proportion of hens on the nest was saved if incubation had not been started. Flushing bars were more effective in the afternoon than the forenoon hours. Effectiveness was well correlated with the condition of the hay crop; as the density and height of the hay increased, the effectiveness of the bar decreased rapidly. A possible "security threshold" factor related to the density of the cover, which may influence the likelihood a hen will flush, is suggested. It is not known if the use of the flushing bar actually resulted in additional pheasants in the fall populations; there was no noticeable increase attributable to their use. The principle of "carrying capacity" may act to cancel any initial gain resulting from the use of flushing bars.
Proceedings of the Iowa Academy of Science
©1959 Iowa Academy of Science, Inc.
Klonglan, Eugene D.; Robbins, Russel L.; and Ridley, Bromfield L.
"Evaluation of Effectiveness of Pheasant Flushing Bars in Iowa Hayfields,"
Proceedings of the Iowa Academy of Science, 66(1), 534-552.
Available at: https://scholarworks.uni.edu/pias/vol66/iss1/73