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Food Habits of Diving Ducks in the Great Lakes
After the Zebra Mussel Invasion

Christine M. Custer & Thomas W. Custer

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Abstract: Zebra mussels (Dreissena polymorpha) invaded the Great Lakes in the mid-1980s and quickly reached high densities. The objective of this study was to determine current consumption of zebra mussels by waterfowl in the Great Lakes region. Feeding Lesser Scaups (Aythya affinis), Greater Scaups (A. marila), Canvasbacks (A. valisineria), Redheads (A. americana), Buffleheads (Bucephala albeola) and Common Goldeneyes (B. clangula) were collected in western Lake Erie and in Lake St. Clair between fall and spring, 1992-1993 to determine food habits. All 10 Redheads, 97% of Lesser Scaups, 83% of Goldeneyes, 60% of Buffleheads and 9% of Canvasbacks contained one or more zebra mussels in their upper gastrointestinal tracts. The aggregate percent of zebra mussels in the diet of Lesser Scaups was higher in Lake Erie (98.6%) than in Lake St. Clair (54.4%). Zebra mussels, (aggregate percent) dominated the diet of Common Goldeneyes (79.2%) but not in Buffleheads (23.5%), Redheads (21%) or Canvasbacks (9%). Lesser Scaups from Lake Erie fed on larger zebra mussels ( = 10.7 ± 0.66 mm SE) than did Lesser Scaups from Lake St. Clair ( = 4.4 ± 0.22 mm). Lesser Scaups, Buffleheads and Common Goldeneyes from Lake Erie consumed zebra mussels of similar size.

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This resource is based on the following source (Northern Prairie Publication 0951):

Custer, Christine M., and Thomas W. Custer.  1996.  Food habits of diving ducks 
     in the Great Lakes after the zebra mussel invasion.  J. Field Ornithology 
     67(1):86-99.

This resource should be cited as:

Custer, Christine M., and Thomas W. Custer.  1996.  Food habits of diving ducks 
     in the Great Lakes after the zebra mussel invasion.  J. Field Ornithology 
     67(1):86-99.  Jamestown, ND: Northern Prairie Wildlife Research Center 
     Online.  http://www.npwrc.usgs.gov/resource/birds/divduck/index.htm
     (Version 31JAN2002).

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Table of Contents

• Introduction
• Methods
• Results
  • Spring and fall diets
  • Size of zebra mussels
  • Winter Season
• Discussion
• Acknowledgments
• Literature Cited

Tables and Figures

• Table 1 -- Frequency of occurrence and aggregate percent of food in the upper gastrointestinal tract of five species of diving ducks.
• Table 2 -- Size of zebra mussels consumed by six species of diving ducks.

• Figure 1 -- Three general locations where six species of diving ducks were collected.
• Figure 2 -- Size distribution of zebra mussels from the upper gastrointestinal tracts of Lesser Scaups and Buffleheads.

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Christine M. Custer and Thomas W. Custer, National Biological Service, Northern Prairie Science Center, P.O. Box 818, La Crosse, Wisconsin 54602 USA
Current Address: National Biological Service, Upper Mississippi Science Center, P.O. Box 818, La Crosse, Wisconsin 54602 USA

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