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Adamus, P. R. 1996.  Bioindicators for assessing ecological integrity of 
     prairie wetlands. Environmental Protection Agency, National Health and 
     Environmental Effects Research Laboratory, Western Ecology Division, 
     Corvallis, OR, USA.  EPA/600/R-96/082. U.S.

Agresti, A. 1996.  An Introduction to Categorical Data Analysis.  John Wiley 
     and Sons. New York, NY, USA.

Bartonek, J. C. and J. J. Hickey.  1969.  Food habits of canvasbacks, redheads,
     and lesser scaup in Manitoba. Condor 71:280-290.

Bartonek, J. C. and H. W. Murdy.  1970.  Summer foods of lesser scaup in 
     subarctic taiga. Journal of the Arctic Institute of North America 
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Bataille, K. J. and G. A. Baldassarre.  1993.  Distribution and abundance of 
     aquatic macroinvertebrates following drought in three prairie pothole 
     wetlands. Wetlands 13:260-269.

Bouffard, S.H. and M.A. Hanson. 1997. Fish in waterfowl marshes: waterfowl 
     managers' perspective. Wildlife Society Bulletin 25:146-157.

Breslow, N.R. and D.G. Clayton.  1993.  Approximate inference in generalized 
     linear mixed models. Journal of the American Statistical Association 
     88:9-25.

Brinkman, M. A. and W. G. Duffy.  1996.  Evaluation of four wetland aquatic 
     invertebrate samplers and four sample sorting methods.  Journal of 
     Freshwater Ecology 11:193-200.
	
Chura, J. J.  1961.  Food availability and preferences of juvenile mallards.  
     North American Wildlife Conference Transactions 26:121-133.

Corkum, L. D.  1984.  Movements of marsh-dwelling invertebrates. Freshwater 
     Biology 14:89-94.

Cox, R. R., Jr., M. A. Hanson, C. C. Roy, N. H. Euliss, Jr., D. H. Johnson, and
     M. G. Butler. 1998.  Mallard duckling growth and survival in relation to 
     aquatic invertebrates. Journal of Wildlife Management 62:124-133.

Danell, K. and K. Sjöberg.  1980.  Foods of Wigeon, teal, mallard and pintail 
     during the summer in a Northern Swedish Lake.  Viltrevy 11:141-167.

Elmberg, J., P. Nummi, H. Pöysa, and K. Sjöberg.  1992.  Do intruding predators
     and trap position affect the reliability of catches in activity traps? 
     Hydrobiologia 239:187-193.

Gerard, P. D., D. S. Smith, and G. Weerakkody.  1998.  Limits of retrospective 
     power analysis.  Journal of Wildlife Management 62:801-807.

Hanson, M. A., C. R. Roy, and K. D. Zimmer.  1995.  Bait fish effects on 
     wetland invertebrate communities and mallard ducklings-preliminary results 
     and conclusions. p. 167-196. In B. Joselyn (ed.) Summaries of Wildlife 
     Research Findings 1995. Minnesota Department of Natural Resources, Section
     of Wildlife, St. Paul, MN, USA.
 
Hanson, M. A. and M. R. Riggs.  1995.  Potential effects of fish predation on 
     wetland invertebrates: a comparison of wetlands with and without fathead 
     minnows. Wetlands 15:167-175.

Keene, O. N.  1995.  The log transformation is special.  Statistics in Medicine
     14:811-819.

Kelsey, J., W. D. Thompson, and A. S. Evans.  1996.  Methods in Observational 
     Epidemiology.  Oxford University Press, New York, NY, USA.

Krapu, G. L. and K. J. Reinecke.  1992.  Foraging ecology and nutrition. p. 
     1-29. In B. D. Batt, A. D. Afton, M. G. Anderson, C. D. Ankney, D. H. 
     Johnson, J. A. Kadlec, and G. L. Krapu (eds.) Ecology and Management of 
     Breeding Waterfowl. University of Minnesota Press, Minneapolis, MN, USA.

Littell, R. C., G. A. Milliken, W. W. Stroup, and R. D. Wolfinger.  1996.  
     SAS System for Mixed Models.  SAS Institute Inc., Cary, NC, USA.

Manly, B. F.  1992.  The Design and Analysis of Research Studies.  Cambridge 
     University Press, New York, NY, USA.

Merritt, R. W. and K. W. Cummins (eds.). 1984.  An Introduction to the Aquatic
     Insects of North America. Kendall/Hunt Publishing Company, Dubuque, IA, USA.

Muller, K. and V. A. Benignus.  1992.  Increasing scientific power with 
     statistical power.  Neurotoxicology and Teratology 14:211-219.

Murkin, H. R., P. G. Abbott, and J. A. Kadlec.  1983.  A comparison of activity
     traps and sweep nets for sampling nektonic invertebrates in wetlands.  
     Freshwater Invertebrate Biology 2:99-106.

Murkin, H. R. and D. A. Wrubleski. 1988.  Aquatic invertebrates of freshwater 
     wetlands: function and ecology. p.239-249. In D. D. Hook, W. H. McKee, Jr.,
     H. K. Smith, J. Gregory, V. G. Burrell, Jr., M. R. Devoe, R. E. Sojka, S. 
     Gilbert, R. Banks, L. H. Stolzy, C. Brooks, T. D. Matthews, and T. H. Shear 
     (eds.) The Ecology and Management of Wetlands. Volume 1: Ecology of 
     Wetlands. Croom Helm, London, England.

Pennak, R. W. 1989.  Freshwater Invertebrates of the United States: Protozoa 
     to Mollusca. John Wiley and Sons, New York, NY, USA.

Perret, N. G.  1962.  The spring and summer foods of the common mallard (Anas 
     p. platyrhynchos L.) In south central Manitoba.  M.S. Thesis. University 
     of British Columbia, Vancouver, BC, Canada.
 
Resh, V. H. and J. K. Jackson.  1993.  Rapid assessment approaches to 
     biomonitoring using benthic macroinvertebrates. p. 195-233. In D. M. 
     Rosenberg and V. H. Resh (eds.) Freshwater Biomonitoring and Benthic 
     Macroinvertebrates. Chapman and Hall, New York, NY, USA.
 
Ringelman, J. K. and L. D. Flake.  1980.  Diurnal visibility and activity of
     blue-winged teal and mallard broods. Journal of Wildlife Management 44:
     822-829.

Ross, L. C. and H. R. Murkin.  1989.  Invertebrates. p. 35-38. In E. J. Murkin
     and H. R. Murkin (eds.) Marsh Ecology Research Program: Long-term 
     Monitoring Procedures Manual.  Delta Waterfowl and Wetlands Research 
     Station, Portage la Prairie, MB, Canada. 

Sjöberg, K. and K. Danell.  1982.  Feeding activity of ducks in relation to 
     diel emergence of chironomids.  Canadian Journal of Zoology 60:1383-1387.
 
Stewart, R. E. and H. A. Kantrud.  1971.  Classification of natural ponds and
     lakes in the glaciated prairie region. U.S. Fish and Wildlife Service, 
     Washington, DC, USA.  Resource Publication 92.

Sugden, L. G.  1973.  Feeding ecology of pintail, gadwall, American widgeon, 
     and lesser scaup ducklings.  Canadian Wildlife Service Report Series 24.  
     Ottawa, ON, Canada.

Swanson, G. A.  1977.  Diel food selection by Anatinae on a waste-stabilization
     system.  Journal of Wildlife Management 41:226-231.

Swanson, G. A.  1978.  Funnel trap for collecting littoral macroinvertebrates.
     Progressive Fish-Culturist 40:73.

Swanson, G. A.  and A. B. Sargeant.  1972.  Observation of nighttime feeding 
     behavior of ducks.  Journal of Wildlife Management 36:959-961.

Turner, A. M. and J. C. Trexler.  1997.  Sampling aquatic invertebrates from 
     marshes: evaluating the options.  Journal of the North American 
     Benthological Society 16:694-709.

Whitman, W.R. 1974. The response of macro-invertebrates to experimental marsh
     management. Ph.D. Thesis. University of Maine, Orono, ME, USA.		

Manuscript received 18 May 1999; revision received 14 September 1999; accepted
     15 November 1999.