For the 10th spring in a row, Bend Park & Recreation District staff is working to control the local Canada goose population by coating their eggs in corn oil.

Jeff Amaral, natural resources manager for the district, said the oil keeps oxygen from entering the egg, which prevents embryo development. Oiling eggs is one of several techniques the district uses to manage geese, along with scaring geese away, and relocating them to Summer Lake Wildlife Area.

The district began oiling eggs in 2009 to manage an overabundance of Canada geese living in Bend parks. Amaral said having too many geese in an area harms the grass and causes erosion along riverbanks. He added that goose droppings affect the way visitors use parks, keeping them from sitting or taking their shoes off.

Geese typically mate during February and nest in March. While the district looks for eggs from March through June, Amaral said the majority of eggs are oiled in April. The number of eggs oiled increased from 18 in 2009 to 220 in 2017, peaking in 2015, when 365 eggs were oiled.

Because the majority of eggs are on private property, Amaral encouraged residents to contact the park district if they know of nests near their homes.