Estimating Breeding Populations of Canada Geese in the Midwest



Principal Investigator:

Robert W. Klaver

Student Investigator:

Brenna Towery (M.S. Graduate)




January 2013 to September 2017

Funding Source(s):

Iowa Department of Natural Resources

U.S. Geological Survey


Updated measurements of Canada goose distribution and nest survival are essential to develop and evaluate management strategies. Iowa's protocols for monitoring the Canada goose breeding population use a stratified random sampling method to select square-mile sections to be surveyed by helicopter. Precise population estimates require that the universe of survey plots be accurately stratified. I provided a more statistically rigorous method of stratifying Iowa's square-mile sections by developing a model to predict Canada goose breeding pair densities by incorporating updated National Wetlands Inventory data and previous breeding population survey data. I found that breeding pairs were best predicted by the wetland types, number of wetlands, area of each wetland type, and a quadratic of the area of each wetland type in each section, as well as an interaction between the wetland types and the area of each wetland type, and random effects for observations and sections. The model indicated that goose densities are highest at large semi-permanent marshes. Reliable estimates of Canada goose nest survival allow management agencies to evaluate available nesting habitats and determine appropriate management techniques. I monitored Canada goose nests at five state-managed wetland complexes to determine how nesting habitat influenced nest survival rates at rural wetlands in north-central Iowa. I found that nest structures produced significantly higher nest survival than nests on islands and muskrat houses. I also found that shallow lake renovation activities at Rice Lake Wildlife Management Area, which involved manipulating the water level, had a negative impact on Canada goose nest survival.


Future Plans:

The project has been completed.

The following papers have been published / accepted:

Ness, B. N. and R. W. Klaver (2016). "Canada Goose Nest Survival at Rural Wetlands in North-central Iowa." Wildlife Society Bulletin 40(4): 705-713.

Koford, R. R., G. Dodici, G. Zenner, J. A. Vogel, B. Ness and R. W. Klaver (2016). "Influence of Patch Shape on Mallard Nest Survival in Northern Iowa." Wildlife Society Bulletin 40(4): 714-721. 

Ness,, B.N., R.W. Klaver, and G.G. Zenner.  In Press.  Long-term changes in Canada goose nest success and nest densities at an Iowa wetland complex.  The Prairie Naturalist.