Some considerations in modeling the mallard life cycle
We outline a population model proposed to accommodate the full life cycle of the mallard (Anas platyrhynchos). Events during the breeding season are better understood than events at other times of the year, but recent findings suggest the importance of phenomena away from the breeding grounds. Several processes are discussed relative to mallard population dynamics. Compensatory mortality is a poorly understood concept, but one that can overwhelm many other components of a population model. Diseases and environmental contaminants can inflict indirect as well as direct mortality and can reduce reproduction. They interact with numerous other variables in complex and yet unknown ways. Recent evidence of a wintering-ground effect on subsequent recruitment provides one avenue for modeling phenomena occurring at different times of the year. Finally, the role of heterogeneity among individuals is widely acknowledged but not fully appreciated. We illustrate with an example the importance of heterogeneity to population processes, including compensatory mortality.
Citation Information
Publication Year | 1988 |
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Title | Some considerations in modeling the mallard life cycle |
Authors | D. H. Johnson, J. D. Nichols, M.J. Conroy, L.M. Cowardin |
Publication Type | Book Chapter |
Publication Subtype | Book Chapter |
Index ID | 85378 |
Record Source | USGS Publications Warehouse |
USGS Organization | Northern Prairie Wildlife Research Center |