Factors influencing spring migration chronology of Lesser Scaup and Mallards
Dr. Scott Petrie, Long Point Waterfowl Executive Director
Dr. Michael Schummer, Long Point Waterfowl Scientist
Dr. Irena Creed, Western University
The Waterfowl Breeding Population and Habitat Survey (WBPHS) is conducted every spring in North America. Estimates of waterfowl breeding populations from the WBPHS are a critical component used in setting of harvest regulations in North America. Timing of the WBPHS generally coincides with spring migration and settling of Mallards (Anas platyrhynchos) on breeding areas; however, because Lesser Scaup (Aythya affinis) are thought to migrate based on different cues than Mallards, population estimates for this species derived from the WBPHS may be biased.
The timing of peak spring migration differs between Lesser Scaup and Mallards, with Lesser Scaup generally migrating relatively later, although both species are migrating during March, April, and May. Variation in spring migration chronology between Lesser Scaup and Mallards may be related to differences in habitat use, foraging behavior, and the seasonal availability of habitat types. Foraging habits of Mallards allow them to take advantage of agricultural waste grain in fields when wetlands required by Lesser Scaup still remain frozen, thus enabling a relatively earlier progression of spring migration by Mallards. Because Lesser Scaup and Mallards have different foraging strategies and habitat requirements, they likely respond to different environmental cues during spring migration. Thus, annual variability in environmental conditions may influence the likelihood that Lesser Scaup and Mallards migrate synchronously or at substantially different rates and times.
From 2005 – 2010, Long Point Waterfowl, the Pennsylvania Game Commission and Dr. Al Afton (U.S. Geological Survey, Louisiana Cooperative Fish & Wildlife Unit, Louisiana State University) led efforts to capture and implant Lesser Scaup with satellite transmitters at Long Point, Ontario (n= 48) and Presque Isle Bay, Pennsylvania (n = 7; Lake Erie) and Pool 19 (Mississippi River, n = 58). Taylor Finger will use these satellite data and determine how spring migration chronology by Lesser Scaup may be influenced by temperature, precipitation, snow and ice cover.
Taylor Finger began his graduate work in January of 2012 and will use long-term data from spring waterfowl surveys conducted by North Dakota Game and Fish to make within-season comparisons of the timing of Lesser Scaup and Mallard migration. Taylor aims to provide insight into annual variation in timing of spring migration by Lesser Scaup for potential use in population modeling efforts for these ducks.