Northern Prairie Wildlife Research Center
During recent studies of breeding waterfowl in the prairie pothole region of North America, high densities of duck nests were found in fields of grass-legume cover established on former cropland (Duebbert 1969, Duebbert and Lokemoen 1976). Factors believed to be responsible for these high densities were tall and dense nesting cover, high nest survival rates, adjacent high quality wetlands, and diversified upland land use. We hypothesized that high nest densities were maintained at these quality nesting tracts when adult hens and their female progeny returned the following year. To test our hypothesis it was necessary to identify breeding hens and their female offspring on the nesting grounds using permanent markers to examine homing of hens by age and breeding success for several years.
The major objectives of this study were to determine (1) return rates of mallards, gadwalls, and blue-winged teal as related to nesting success in various cover types, (2) factors influencing nest site selection by the 3 species, and (3) relationships between age and productivity with respect to arrival dates, nest initiation, nesting period, clutch size, and breeding success.
Acknowledgements. This study was conducted with support and guidance of the Northern Prairie Wildlife Research Center (NPWRC) DirectorateW. R. Goforth, G. A. Grau, R. C. Stendell, and D. L. Trauger. We appreciate the assistance in obtaining access to study areas and logistical support provided by L. M. Kirsch and L. J. Schoonover. Field data were collected through the dedicated efforts of J. D. Anderson, J. T. Beall, W. J. Berg, S. L. Fiegel, B. H. Garlinger, D. H. Johnson, J. J. Johnston, R. C. Kenyon, R. R. Naze, L. G. Nelson, and J. K. Patterson. We also appreciate field assistance provided during peak workload periods by E. K. Bartels, W. B. Bicknell, L. C. Diede, M. P. Dryer, R. L. Duval, J. P. Fleskes, M. A. Hay, K. F. Higgins, H. A. Kantrud, A. P. Ludden, A. R. Lund, M. R. McEnroe, K. A. Nemec, D. L. Orthmeyer, F. H. Roetker, B. J. Schaller, C. W. Shaiffer, S. G. Simpson, and S. J. Young. We received good cooperation in maintaining field station facilities from NPWRC maintenance staff, including V. A. Gums, L. F. Hemen, S. A. Hollingsworth, R. W. Opp, J. A. Romelfanger, and D. Van Asperen, Propagation facilities at NPWRC, operated by F. B. Lee and C. R. Telken, maintained captive birds needed for the project in excellent condition. Data entry was provided by S. A. Harris, C. L. Nustad, and D. J. Rova, and statistical analyses were accomplished by D. A. Davenport, D. H. Johnson, T. L. Shaffer, H. B. Harvey, and D. W. Sparling. Banding data and analyses were supplied by J. D. Nichols of Patuxent Wildlife Research Center. The insights and advice received through discussion and manuscript review provided by colleagues L. M. Cowardin, D. H. Johnson, G. L. Krapu, and J. R. Serie were appreciated. Also, we benefitted from reviews of the manuscript by the editor and consulting editors.