Summerlake Park Goose Invasion Thwarted

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Summerlake Park, Tigard.
Summerlake Park, Tigard.

By Ygal Kaufman for Tualatin Life

Canadian geese are glorious, majestic creatures that nest all over North America. According to the most recent numbers, there are over five million in the United States, and Oregon is one of their favorite destinations. Unfortunately for the residents of Tigard and the fans of Summerlake Park, these birds have taken a shining to the area and their waste has presented real problems for the city. This past spring, the enterprising minds at the Parks & Recreation department got creative and used an interesting new solution to curb the population problem; egg depredation.

Steve Martin is the Parks and Facilities Manager for the city of Tigard. We spoke to him about the city’s Canadian goose problem and how he solved it.

“Typically in the past, natural events have done a lot to keep the goose population down. And lately they haven’t, so the goose population has been spiraling out of control,” says Martin of the challenges facing the city. Among the causes of natural thinning in the ranks of the geese are the local predatory populations like coyotes. “A lot of the geese will move on when the lake freezes over all the way- which it hasn’t for a little while – and there’s no safe place for them to stay at the lake when it freezes over, so a lot of them would have left and not come back in the spring,” says Martin of the other chief cause of why normally the goose population isn’t a problem.

Compounding the problem is the fact that geese tend to come back to where they’re hatched. They tend to have 2-8 eggs per female with an incubation period of just under a month. When this is combined with the geese that haven’t left from the previous season, it adds up quickly.

“They come back and raise their own young there.  So you can imagine the population will grow astronomically, and there are very few predators at Summerlake,” says Martin of the population explosion.

Over the past few years, the goose population issues have been mounting.

“We observed that there were more and more geese, and from the neighbors and people using the park- the number of complaints kept rising.  In past years it was just a couple of complaints, but this year there were an awful lot. You did not want to walk on the pathways, it was pretty nasty, and the park was becoming pretty much unusable,” Martin says of the park’s state under layers of droppings.

As glorious as the Canadian goose may be, a flock of just 50 of them will produce over two and half tons of excrement per year, according to a National Geographic report.

“This year, to try and control it for coming years, we used one of the few ways you can actually work with migratory birds, which is egg depredation,” says Martin, “which keeps the eggs from hatching.”

Egg depredation is  the endorsed method by Ducks Unlimited and other conservatory groups to control Canadian goose populations. “Usually you try to get rid of most of the nests, especially with a population that’s already out of control. You figure you’ll find most of the nests, but probably not all of them.”

With egg depredation, the eggs are treated, or  “addled,” in some way to prevent the embryo from growing, as opposed to literally destroying or removing the eggs.

“If the eggs don’t hatch, the geese then leave, whereas if you broke the eggs or cooked them, the geese would just hatch more,” says Martin, “with depredation, they will then abandon the nest and go away.”

The most commonly effective and accepted method of depredation is to apply a layer of corn oil to the eggs. The oil prevents the egg from getting oxygen and the embryo is deprived, killing the embryo within the first two weeks of incubation. There are other methods, such as shaking or puncturing the eggs, which are less successful and sometimes can lead to survival of the embryo and deformed hatchlings.  Depredation is the most humane current method of population control and is endorsed by Ducks Unlimited as well as the Humane Society of the United States.

Oregon is a particular hub of Canadian goose populations, as it sits squarely in a region that is climatically perfect for them to live in, breed in and winter in. Often the birds and live and breed up north, in Canada, then fly south for the winter. But Oregon provides just the right climate to potentially stay all year, breeding and wintering in the same spot… namely Summerlake Park.

“In the fall, we may engage the same contractor, who has herding dogs who are really good at staying there and making the geese nervous enough that they leave,” says Martin of the city’s future plans for dealing with bird populations. He leaves the options open to return to depredation or explore other methods of making Summerlake Park enjoyable and walkable again for Tigard’s residents. For now, though, mission accomplished, says Martin.

“We’re done for the year, there are no more eggs being hatched right now.”

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