Where have all the seabirds gone? A tufted puffin on Prince William Sound, Alaska. At left, a pair of murrs sit on the cliff on St. Paul Island, Alaska (AP photos)
Where have all the seabirds gone?
Lexile

The number of seabirds, including gulls, puffins and auklets, has dropped significantly in the Gulf of Alaska and northeast Bering Sea, a possible consequence of warmer waters, according to a preliminary federal analysis of nearly 40 years of surveys.

U.S. Geological Survey experts found that the seabird population density declined 2 percent annually from 1975 to 2012 in the northeast North Pacific, said John Piatt, research wildlife biologist at the USGS Alaska Science Center.

"Biologically speaking, that's a pretty major change," he said.

Piatt and researcher Gary Drew suspect the decline may be tied to less food availability, a consequence of warmer ocean temperatures that occur in cycles over decades.

Seabird populations could bounce back as water cools, Piatt said, but decadal cycles could ultimately be superseded by global warming.

"That's what a lot of people are concerned about," he said. "We don't know. We're just learning about the Pacific Decadal Oscillations and that they're important."

The analysis of seabird surveys began in earnest in 1989.

"We started pulling together some of these data bases after the Exxon Valdez oil spill when it was clear we needed to get a better handle on densities of birds at sea to assess damages," Piatt said.

The result was the creation of the North Pacific Pelagic Seabird Database. It includes bird counts from 350,000 ship transects, the plotted paths to systematically make measurements.

To make sense of the numbers, researchers looked for blocks of water where at least 10 surveys had been conducted in a given year in all four decades.

"We pulled out places where there was repetition. It gave us 72 blocks of water for which we had data spanning 40 years," Piatt said.

Exxon Valdez oil killed a lot of birds, Piatt said, but seabird numbers also declined outside the spill area.

"It was much bigger than the oil spill," Piatt said.

Starting in the late 1970s, atmospheric circulation changed. Water temperatures that had been colder than average for a decade shifted to several degrees warmer than average for more than 30 years.

The changes were tied to effects from Pacific Decadal Oscillations. The term describing climate variability was coined by fisheries scientist Steven Hare, who researched connections between Alaska salmon production cycles and Pacific climate. NASA describes the oscillations as long-term ocean fluctuations that wax and wane every 20 to 30 years.

With warmer water, phytoplankton bloomed earlier. Zooplankton fed on phytoplankton and developed earlier, providing abundant food for early spawning fish such as halibut, pollock and cod and leaving less food for late spawners such as capelin, a type of smelt consumed by seabirds.

"This was a magnitude-9 earthquake in the ecosystem," Piatt said. "Everything changed afterward, including marine birds."

Counts at bird colonies were not part of the USGS review. U.S. Fish and Wildlife Service seabird researcher David Irons said trends at colonies are generally in sync with the at-sea data. Seabird numbers fell at some colonies in the mid-1980s and afterward but eventually leveled off or increased.

"Basically the decline leveled off around 2000," Irons said.

The USGS review goes through 2012. As water temperatures have cooled in recent years, some bird numbers have ticked up, Piatt said. The historical record indicates wildlife such as salmon has booms and busts in population corresponding to natural cycles in the environment.

"The animals are responsive to changes in the environment," he said.

The more worrisome issue is global warming that could supersede decadal pulses.

"The background increase in global temperature is a happening fact," he said. "It's not hypothetical."

Critical thinking challenge: How did warmer water lead to fewer birds?

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COMMENTS (13)
  • TamraD1
    4/06/2015 - 08:35 a.m.

    The effect of global warming and the warmer water is causing the birds to die off and they might or might not have a chance to come back in these type of environments..

  • Malikc1
    4/06/2015 - 08:36 a.m.

    alot of seabirds have been disappearing all over the world , and people are curious where they are going. scienctist are thinking that tghey are migrating south

  • hannaht-Goo
    4/06/2015 - 08:46 a.m.

    Warmer water lead to fewer birds. The text states, "U.S. Geological Survey experts found that the seabird population density declined 2 percent annually from 1975 to 2012 in the northeast North Pacific, said John Piatt, research wildlife biologist at the USGS Alaska Science Center." In the long run that's a major change in population. The text also states, "Piatt and researcher Gary Drew suspect the decline may be tied to less food availability, a consequence of warmer ocean temperatures that occur in cycles over decades." They don't know why there are fewer birds with warm water but they are worried about global warming. The evidence from the text explains why there are more birds with colder water and fewer birds with warmer water.

  • cobys-Goo
    4/06/2015 - 08:49 a.m.

    Their has been a decline in seabirds along the gulf of Alaska. The text states that the seabird population density dropped by 2%. The text also states the water is warming up and that is a very good reason the population is going down. Evidence from the text suggest that if the water cools back up then we won't have to worry about the population going down.

  • stevef-Goo
    4/06/2015 - 08:55 a.m.

    There has been fewer sea birds in the environment due to warmer temperatures. The text states that warmer temperatures have lead to fewer birds. The text also states that because of warmer water the zoo plankton bloomed earlier so the fish in the areas that were tested so they didn't have any food. Since the fish in the area didn't have any food it lead to a decline in sea birds because they didn't have any food.

  • noahd-Goo
    4/06/2015 - 09:01 a.m.

    Warmer water leading to fewer birds.The text states that some problems are not as much food available. The text also states that stopping global warming could stop the bird loss.The evidence from the text suggests the warmer weather is decreasing the population of birds.

  • caitlinl-Goo
    4/06/2015 - 10:42 a.m.

    All the seabirds have vanished. The text states, "The number of seabirds, including gulls, puffins and auklets, has dropped significantly in the Gulf of Alaska and northeast Bering Sea." The text also states, "U.S. Geological Survey experts found that the seabird population density declined 2 percent annually from 1975 to 2012 in the northeast North Pacific, said John Piatt, research wildlife biologist at the USGS Alaska Science Center." The evidence from the text clarifies the data of the disappearing of seabirds.

  • AlbertoM4
    4/06/2015 - 11:24 a.m.

    The declining of sea birds first got noticed during the oil spill,however it is very possible that it could've began long before it. Global warming is a greenhouse effect, caused by excessive amounts of carbon dioxide within the atmosphere. This is caused by the burning of fossils fuels. Although we want to deny it the majority of all environmental issues are caused by humans.

  • AlbertoM4
    4/06/2015 - 11:24 a.m.

    The declining of sea birds first got noticed during the oil spill,however it is very possible that it could've began long before it. Global warming is a greenhouse effect, caused by excessive amounts of carbon dioxide within the atmosphere. This is caused by the burning of fossils fuels. Although we want to deny it the majority of all environmental issues are caused by humans.

  • TreyvaunT
    4/06/2015 - 01:24 p.m.

    I thought those birds were extinct! I like the way they look. Like their colorful beaks. I would be scared if one would come towards me though.

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