Concerned with population control while caring for five captive nesting swan pairs, I used the The Humane Society of the United States Wild Neighbors Program CANADA GOOSE EGG ADDLING PROTOCOL (see links below). The wooden goose eggs (purchased at Michaels craft store, or link below) fooled all but one wild female that rejected them and would push them out of the nest forcing me to “oil” her eggs. The darker color, staining, or slightly different size and weight (see picture with real swan egg in the center) did not seem to make a difference. The previous care givers would rotate the eggs with refrigerated or shaken eggs which was effective, but more disruptive and time consuming. With both methods, after 30-35 days I would pull the dummy eggs, and put back and puncture one of the original eggs that I kept refrigerated. The male and female would then remove the broken egg and instinctively “bury” it in the water to avoid attracting predators. This would complete their “nesting cycle” and after a few hours freed them to leave the nesting area.

links to goose addling sites for detailed information

http://mdc.mo.gov/landwater-care/wildlife-management/nuisance-animal-management/controlling-wild-geese/how-addle-and-o

http://www.humanesociety.org/assets/pdfs/WILD_Goose_Egg_Addling_Protocol.pdf