Wednesday, February 1st, 2023
Wednesday, February 1st, 2023

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MN: So far, little evidence of negative effect on loons from Gulf oil spill

St. Paul – After the Gulf oil spill last year, many people had
concerns about the potential effects on loons in Minnesota, many of
which winter in the area.

While more than 100 dead birds have been recovered in the Gulf –
and more dead ones undoubtedly sank to the bottom or were scavenged
– there seems to be reason for optimism.

The state’s loons have arrived back on their breeding lakes, and
Lori Naumann’s phone has been quiet.

“The biggest gauge is public comments,” said Naumann, of the DNR
nongame wildlife program. “I have not had calls from anyone in a
panic that ‘their loon’ has not returned.

“It seems as if the population has fared pretty well.”

The anecdotal reports that Rich Baker, a wildlife biologist in the
nongame program, has heard mirror that.

“It’s going to take a big picture view, with statistical analysis,
to say if there is anything going on as a result of the oil spill,”
he said. “I would be amazed if it was so dramatic” that people were
already noticing fewer loons.

“I think it’s going to be more subtle – if there is anything to
observe,” Baker said.

While anecdotal information to date suggests a huge number of loons
didn’t perish as a result of the spill, one of the first tests will
be the annual loon-monitoring surveys that take place in early July
on 600 lakes around the state.

More than 30 of those lakes are around the Tamarac National
Wildlife Refuge in northern Minnesota. While refuge biologist Wayne
Brininger won’t have solid data on the number of loons that have
returned until the survey, “we are seeing loons where we typically
see them.”

By the time the survey, which has been conducted for 17 years,
takes place, baby loons haven’t taken off; they’re still swimming
around near the adults, or riding on their backs. As a result, the
DNR can see if there are any changes with adults or young

The 17 years of data gives the agency “a lot of power to detect a
very small change,” Baker said.

So far, 107 loons have been collected in the Gulf since the oil
spill, Naumann said.

But loons are different from most birds in that they have solid
bones, so they sink when they die in the water. As a result, those
birds that have been collected likely are only a small portion of
the loons that actually died.

But even if just 10 percent of the loons that actually died were
recovered – and even if every one of those birds was from
Minnesota, where the estimated loon population is 12,000 – “would
we be able to detect that visually? I doubt it,” Baker said.

And, if there are any changes, people may not notice them

Loons don’t return from the Gulf until they’re 3 years old, so a
certain number of the birds that were in the area when the spill
occurred wouldn’t have come back to Minnesota this spring anyway,
Naumann said.

Some of what occurs could be “sublethal impacts,” over a longer
period of time, Baker said.

“If they are being exposed to the residues down there on the Gulf
every winter, it may not kill them, but it may reduce their
reproductive capacity, or reduce their longevity,” Baker said. “We
will be looking for those factors in the coming years.”

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