16 THE SCIENTIST | the-scientist.com
ANDRZEJ KRAUZEdrifting with the tide, perhaps while sleep-
ing or resting before foraging, the birds
could provide another source of data,
Bowers and Cooper reasoned.
The researchers tracked down the razor-
bill dataset from the Royal Society for the
Protection of Birds, which had tagged the
animals. Cooper, who graduated in 2016 with
his master’s in oceanography, compared the
birds’ movements during periods of apparent
drifting with tidal data, and saw that patterns
in the two datasets mirrored each other. As
the tides sped up, so did the birds, and when
the tide turned, the birds changed direction
by 180° (Ocean Sci, 14:1483–90, 2018). “It’s
overwhelming evidence that they are moving
with the tide,” Cooper says.
Drifting seabirds could offer several
advantages over traditional ocean moni-
toring. While buoys tend to converge in
a few major oceanic streams, birds only
drift for part of the day or night before
picking up and flying to new locales. They
also go places that buoys can’t, such as
close to shore, Bowers adds. And the best
part: the data already exist. “People all
over the world have tagged seabirds to
see where they go,” says Cooper. Using
these animals to assess ocean currents—
“it’s recycling of data.”
It’s not the first time that researchers
have turned to seabirds to monitor physi-cal properties of the world’s oceans. Wil-
lem Bouten, a computational ecologist
at the University of Amsterdam, started
tracking seabirds in the early 2000s and
soon noticed patterns of movement that
seemed to be linked with ocean currents.
He and his colleagues confirmed the drift-
ing behavior among lesser black–backed
gulls (Larus fuscus) in the North Sea off
the coast of the Netherlands. Compar-
ing the birds’ movements to a model of
the tides, they found that “it matched
perfectly,” Bouten says (Ibis, 153:411–15,
2011). And in 2014, Nagoya University
seabird biologist Ken Yoda showed that
tagged streaked shearwaters (Calonectris
leucomelas) could be used to track water
currents off the northeastern coast of
Japan (Prog Oceanogr, 122:54–64).
As living organisms, however, birds are
“not a sensor that you can control,” says
Bouten. And in some cases, their behav-
iors may complicate the data. In Cooper’s
analysis, the speed at which the birds were
moving was not quite the same as the tidal
speed predicted by an oceanographic model.
It could be that the models were wrong, says
Bowers, or that the birds were paddling.
Another risk is that the birds may be
pushed by the wind in a way that causes
their path to deviate from the currents
below the surface, a phenomenon knownas slip. “We have to think about the degree
of slip to estimate ocean currents,” Yoda
tells The Scientist in an email. “Nobody
knows the strength of the effects.” As a
result, he adds, “the method is not an alter-
native to satellites, drifter buoys, or cur-
rent-meter moorings.”Still, he and others argue that seabirds
could provide a wealth of additional infor-
mation on ocean currents. Bouten says
that he and his collaborators have tracked
some three or four hundred birds floating
on the ocean’s surface and that the data are
available to oceanographers. To date, he
hasn’t gotten any requests. “I think that’s
because people are not used to this.”
Bowers agrees. “I suspect that for some
time oceanographers... won’t trust the
seabirds because they’re not perfect drift-
ers,” he says. But, “they’ve got advantages.
I suspect as time goes on, people will
explore those advantages.”
—Jef AkstPassing Marks
Brown and yellow mice nestle side by
side in their cages in Anne Ferguson-
Smith’s molecular genetics lab at the
University of Cambridge. The mice are
Agouti Viable Yellow, naturally occur-
ring mutants, which, though geneti-
cally identical, have coats that vary in
color—a phenomenon that researchers
have long studied as an example of epi-
genetic inheritance.
All of the mutant mice have a gene,
Agouti, that influences coat color, and an
adjacent transposable element—a DNA
sequence that can move about the genome,
creating or reversing mutations—that pro-
motes the gene’s expression. In the brownNOTEBOOKDrifting seabirds could
off er several advantages
over traditional ocean
monitoring.