Warmer ocean temperatures and changing food sources in the ocean could be the reasons for the higher than average amount of seagulls roosting all over Cordova, scientists say.
Since January, water temperatures recorded at the Cordova tide station are four degrees to six degrees warmer than normal, said Mary Anne Bishop, Prince William Sound Science Center’s research ecologist, who holds a doctorate in wildlife ecology.
“The temperatures have been breaking records every month since March,” she said. “The warmer ocean temperatures are changing food sources.”
While it isn’t unusual to see a plethora of seagulls in a coastal community during this time of year, Bishop said she believes there are a few thousand more of the Glaucous-winged gulls in Cordova than usual.
The science center has conducted two gull counts this summer. Preliminary numbers from the count in June estimate that there are 8,000 to 10,000 seagulls roosting in Cordova. The center continues to count the gulls approximately every 10 days.
The birds are in Cordova, Bishop said, because they’re not sitting on nests in colonies on the Copper River Delta.
“The uninhabited barrier islands of the Copper River Delta provide gull nesting habitat,” she said. “There have been colonies of gulls on them for many years. There are also gulls nesting out on Middleton Island and there are some gull colonies in the sound. … There is an estimate that approximately 10,000 pairs nested on Egg Island in the late 60s or early 70s.”
But this year, Bishop said, the nesting colonies failed.
“The gulls are not starving, but they can tell that conditions are not good in which to raise chicks,” Bishop said.
Failing colonies means that gull eggs were not laid, or that the adult gulls destroyed the eggs. “Gulls can survive, but they know when there isn’t enough food, so they don’t bother to nest,” Bishop said.
Bishop was at the mouth of the Copper River in mid-June, and said there were almost no seagull nests there. Some of the nests she examined had no eggs; others had a single egg, or an egg that had been broken by an adult.
“There were very few nests with eggs,” Bishop said. “They just were not nesting.”
Under normal conditions, gulls start nesting around mid-May. About four weeks later, the eggs hatch and then the chicks are able to fly at about 40 days old. Usually, the spike in gull numbers in and around Cordova happens at the end of July, when those fledglings are out of the nest. Bishop said we’re not going to see that spike in numbers this year.
“What we’re seeing is that all of these gulls here in town usually would be giving a lot of time and energy to raising chicks out in the islands,” she said. “Raising chicks would normally keep the adults busy, but there are no chicks to raise, so they’re here. Their natural food supplies appear to be low, that’s why they’re not nesting and why they’re here in town, when they would normally be out on the barrier islands in much higher numbers.”
Now that commercial fishing is in full swing, the waste at the canneries is also a draw for the birds.
“Undoubtedly, the offal brings the birds in,” Bishop said. “The canneries are a reliable source of food at this point. The processors have installed fish meal plants, so that will help.”
Hopefully, and I never thought I’d say it, we’ll see a colder winter, which will help to cool down ocean temperatures, which will increase the gulls’ food supply, and the birds will nest next year. I expect if that happens that we will see decreased numbers of birds here next year.”
City officials are looking into how the abundance of seagulls in town this summer is affecting the rooftops of city buildings.
“I have heard, anecdotally, that gull feces will react with the tiles on the Cordova Center. Gull feces are loaded with uric acid and will cause damage to exposed metal of any kind,” Cordova Mayor Clay Koplin said.
The seagull problem was brought up at the Cordova City Council meeting on June 6. Acting City Manager Michael Hicks said he was researching various ways of keeping the birds off of rooftops.
“We have been looking at different ideas posted on the internet,” he said. “I told the council that we are looking for a cost-effective solution that will work. From what I have heard and read, what works today may not work tomorrow, as they become desensitized to some of the methods.”
Bird pest control may be another viable solution
Cordova resident Carlos Martin is a wildlife and pest bird control contractor with 20 years of experience.
Martin met with City of Cordova staff this week to discuss what could be done about the surplus of seagulls roosting on the Cordova Center.
“Seagulls are flocking birds,” Martin said. “In wildlife and pest bird control we seek to do things which create negative aversions to the flock and will make it uncomfortable for the birds to be there.”
“Personally, I do not want gulls on my roof and I can certainly understand the city not wanting them on the Cordova Center,” Bishop said. “I think they should be trying some different techniques to see if they can discourage the gulls from roosting there.”
But the gull problem isn’t limited to the birds roosting on available rooftops. Some residents have raised concerns that E. coli bacteria may be introduced into the town’s fresh water supply from the their feces.
But Hicks said Cordova’s water supply is unaffected due to the treatment process the city uses.
“Remember, we have thousands of salmon that die off in the lake each year, too,” he said.
So far, there has not been any roof damage from the gulls, he said.
Residents can do a few things to help keep the gulls at bay, Koplin said, such as disposing of fish waste properly and keeping household trash in closed containers.
There soon may be a natural end to Cordova’s seagull dilemma.
“Hopefully this will not be a long-term problem,” she said. “They will be migrating by the end of August or early September and we’ll see a huge drop off in the numbers.”