Nonhunting Mortality of Fledged North American Waterfowl

Abstract

A survey of nonhunting mortality of wild waterfowl was conducted by the Delta Waterfowl Research Station, Delta, Manitoba, 1963-65. Records of reported mortality (n = 2,108,880) for the period 1930-64 were assembled from open literature, unpublished federal reports, and a questionnaire. In addition, nonhunting mortality band recoveries (n = 25,817) for the period 1930-63 were analyzed. Data were compiled on mortality from collisions, weather, predation, pollution, diseases and poisons, and miscellaneous factors. Collision mortality (n = 3,015) was 0.1 percent of the total sample and was reported most commonly from the Central Flyway. Collisions with utility wires and automobiles were the most frequent causes of mortality. Weather-related mortality (n = 158,723) was attributed to 7.4 percent of the total sample. Hail was the most important factor during summer. In other seasons various factors operated in concert with cold weather. Predation (n = 2,621) accounted for 0.1 percent of the total mortality reported. Losses appeared to be of similar magnitude in all flyways and peaked during summer. Mortality from pollution (n = 13,944) was 0.6 percent of the total sample. Losses were concentrated on the Atlantic coast and were proportionally heavier among diving ducks (Aythyinae). Mortality from disease (n = 1,873,970) was 87.7 percent of the total mortality studied. Losses were most prevalent in the Central and Pacific flyways during summer and fall. Mortality from miscellaneous causes (n = 82,424) was 3.8 percent of the total sample. Losses were confined largely to the Mississippi Flyway and to the summer-fall period. The seasonal losses peaked during winter and spring. J. WILDL. MANAGE. 40(4):681-693 This paper summarizes a survey of reported nonhunting mortality of wild waterfowl conducted by the Delta Waterfowl Research Station, Delta, Manitoba, 1963-65. A preliminary discussion of waterfowl nonhunting mortality was given by Cornwell and Hochbaum (1962, paper presented at 24th Midwest Fish Wildl. Conf., Des Moines, Iowa), and a detailed study, including an extensive literature review, was completed by Stout (1967). Boyd (1962) provided further impetus for our study. The objective of the survey was to review and compile qualitative evidence from the available records on nonhunting mortality in waterfowl. Hopefully, this data base will aid in the design of future quantitative studies of nonhunting mortality. Acknowledgment is made to The Wildlife Management Institute for providing a graduate fellowship and other budgetary support and to the Division of Forestry and Wil life Resources, Virginia Polytechnic Institute and State University, for funding and use of facilities.