How to beat the Chicago gulls? Don’t let them rebound

chicago gulls

A reduced gull population in Chicago makes Lake Michigan beaches safer for swimming. Photo: United States Department of Agriculture.

Researchers cut a population of pesky Chicago gulls almost in half by putting oil on their eggs.

The United States Department of Agriculture project was an attempt to control the population of ring-billed gulls on Lake Michigan beaches.

Gulls in Chicago have caused general nuisance, property damage and economic losses. Their excrement threatens the health of beachgoers.

Several studies showed a relationship between ring-billed gulls and increased levels of fecal indicator bacteria, such as E. coli, in the nearshore waters.

Concerns grew when the tests prompted Lake Michigan swim advisories from the Chicago Park District.

E.coli isn’t necessarily harmful, but some Chicago beaches were found to have unsafe levels, said Zvezdana Kubat, assistant press secretary for the district.

“When our beaches test above the standard set for all Great Lakes, we have to notify the public,” Kubat said.

While the gulls aren’t the only cause of beach bacteria, gull overpopulation has been a long-term problem.

The gull’s long life span  contributes to a large adult population, said John Hartmann, a wildlife specialist on the project.

Hartmann and other specialists oiled eggs during nesting season, hoping to reduce the amount of hatch-year ring-billed gulls.

“We actually use food grade corn oil and coat the eggs to inhibit the transmission of oxygen through the egg shell,” Hartmann said. “We do this in the first two weeks after the egg has been laid, before the embryo develops, effectively sterilizing it.”

Egg removal can cause the adult gulls to lay more eggs, but sterilization through egg oiling doesn’t trigger that response, said Hartmann.

The project began under the direction of the Chicago Park District in the spring of 2007 and continues now, as the gull’s nesting season is about to begin.

“Ring-billed gulls arrive in Chicago after winter, and in April they build nests,” Hartmann said. “We scout out the sites while they’re nesting, and in the middle of April they lay their eggs.”

Oiling the eggs has been successful in stabilizing the population without harming it, Hartmann said.

The project’s wildlife specialists followed recommendations from the U.S. Humane Society. The group says that egg management is not considered inhumane if performed in the first two weeks, before the gull embryo begins to develop.

“We’ve seen results,” Hartmann said. “We reduced swim bans on Chicago beaches.”

According to the final report, the gull population was cut 46 percent between 2007 and 2012.

During the 2012 swim season the proportion of tests resulting in a swim advisory declined at 12 of 14 beaches, compared to data from 2006.

Kubat said that while such results are encouraging, gulls aren’t the only factor that leads to unclean water.

“We’re doing a number of things to manage bacteria on our beaches,” Kubat said. “Last year we implemented a predictive modeling system that takes things like wave height and air temperature into account.

“Regarding gulls, we’ve also seen success with canine management – we’ve got border collies chasing the birds away,” she said. “Reducing litter can also prevent attracting them. As always, we’re encouraging beachgoers to throw away their garbage and to stop feeding the gulls.”

  • Pingback: PSA: Don’t feed the birds | World of Birds

  • Laurie

    I’m with Harold. I live in a beach-front community, and have heard the e-coli blamed on the gulls, but believe me, if they tested for dna, it would be human poop, and not the birds, that is causing the problem.

    The Metropolitan Water Reclamation District in Chicago has had its “poop” gates open to Lake Michigan since last Thursday, dumping millions of gallons of untreated sewage into the lake. This contaminates our shoreline sand, which washes into the lake even after the lightest rains, and triggers the warnings that lead to beach closings.

    Its a pattern we’re all familiar with: it rains, and the beaches close. Even when the MWRD isn’t dumping raw sewage, our lake-front sanitary sewers are old and leaky, and human waste co-mingles with the storm water that is piped into the lake.

    To blame it on the sea gulls is ridiculous. And oiling cormorant eggs is despicable.

  • Scoop

    Gulls and geese are a big part of the problem in northern Lake Michigan. It’s a no-brainer; they and their poo is everywhere! The piers some days are covered from one end of the other in gulls. Common sense says there are too many when one can’t even walk there any more without stepping in crap, and boats in the marinas are pelted daily. This might sound cruel to some but IMO we should be managing gulls just like we manage geese and other critters. If not lethal control like for cormorants, then perhaps oiling eggs at nesting sites for a while to reduce numbers. srtave

  • Kathleen

    Great comment, Harold…thank you. Too often, humans refuse to see themselves as part of the problem–it’s always easier to “manage” nonhuman animals than to accommodate them or change our own ways. I’m just thankful to hear that a lethal management tool wasn’t reached for first, which is so often the case.

  • Debbie

    Yeah, I agree with Harold. Hate that the animals always seem to have to pay for what is largely a human-caused problem. Most of that E. coli is coming from somewhere else.

  • Harold

    This article is even more interesting if you replace the word “gulls” with “people”, e.g.:

    “People in Chicago have caused general nuisance, property damage and economic losses. Their excrement threatens the health of beachgoers.

    Several studies showed a relationship between people and increased levels of fecal indicator bacteria, such as E. coli, in the nearshore waters.”