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A28 SCIENCE
Tuesday 11 december 2018

Croak to croon: City frogs sing more alluring love songs

By CHRISTINA LARSON increases,” said Halfwerk.
AP Science Writer “The best adaptation is to
WASHINGTON (AP) — City be the most attractive, with
frogs and rainforest frogs an elaborate love song.”
don’t sing the same tune, Corinne Lee Zawacki, a
researchers have found. biologist at the University
A study released Monday of Pittsburgh who was not
examined why Panama’s involved in the study, said
tiny tungara frogs adapt the researchers’ methodol-
their mating calls in urban ogy confirmed that urban-
areas — an unexpected ization is the reason for the
example of how animals call changes.
change communication “I love the choice of study
strategies when cities en- system,” she said.
croach on forests. “A lot of background re-
These frogs take advan- search has already been
tage of the relative ab- done on this frog. So we
sence of eavesdropping can see clearly how urban-
predators in cities to belt ization changes the inter-
out longer love songs, play of natural and sexual
which are more alluring to selection” — or the trade-
female frogs. offs between survival and
Tungara frogs don’t croak courtship goals.
like American bullfrogs. But not all amphibians are
To human ears, their dis- as lucky as Panama’s tun-
tinctive call sounds like a In this undated photo provided by researchers in December 2018, a male tungara frog in Panama gara frogs.
low-pitched, video-game uses his vocal sac to call out in Gamboa, Panama. “Amphibian populations
beep. Associated Press are declining worldwide,
To female frogs, it sounds Whether the female frogs that extended frog calls belt their hearts out. mostly due to habitat de-
like pillow talk. hailed from the city or significantly increased the “An urban male can take struction,” said Andrew
Every evening at sunset, forest themselves, they risk of attracting predators. greater risks,” said lead au- Blaustein an ecologist at
the 1-inch male brown showed the same prefer- In the rainforest, the frogs thor Wouter Halfwerk, an Oregon State University,
frogs crawl into puddles ence for fast-paced, com- must balance two goals: ecologist at Vrije University who was not involved in
to serenade prospective plex crooning that com- attracting a mate and in Amsterdam. the study.
mates. The lady frog selects bines high and low tones in staying safe. A town frog also has to “This is a rare case — and
a mate largely based on quick arrangements. In the city, there are no work harder to find a mate a very interesting case — of
his love song. Study co-author Michael frog-eating bats, and far because lady frogs are rar- an animal adapting quick-
Researchers found that J. Ryan, a biologist at the fewer snakes and midges. er in the city. ly, in evolutionary terms, to
the urban frogs call faster, University of Texas who has The male frogs are freer to “Competition for females new circumstances.”q
more frequently and add studied tungara frogs for
more embellishments — a more than 30 years, said
series of staccato “chucks” that the high and low notes NASA’s Voyager 2 becomes
on the end of the initial likely stimulated the inner
whine — compared with and outer ear chambers of 2nd craft in interstellar space
those in the forest. female frogs in a pleasur-
Those fancy urban love able or interesting way.
songs are three times more So why don’t rainforest By SETH BORENSTEIN
likely to attract the la- frogs sing the same way? AP Science Writer
dies, as scientists learned The scientists set out to WASHINGTON (AP) —
by playing back record- confirm their hypothesis NASA’s Voyager 2 is now
ings of both city and forest that frogs that added ex- the second human-made
frog calls to an audience tra high-pitched “chucks” object to zip away from
of female frogs in a labo- attracted not only more the sun into the space be-
ratory. Thirty of 40 female mates, but also more trou- tween the stars.
frogs hopped over to the ble from frog-eating bats Voyager 2 last month exit-
speaker playing the urban and parasitic midges. With ed “this bubble that the sun
frog calls, the researchers the help of camera traps creates around itself,” long-
report in the journal Nature and sticky paper, the re- time NASA mission scientist
Ecology & Evolution. searchers demonstrated Ed Stone said Monday. The
spacecraft is now beyond This is a handout photo from the Jet Propulsion Lab in Passadena,
the outer boundary of the Calif., showing the Voyager spacecraft. NASA’s Voyager 2 has
heliosphere, some 11 billion become only the second human-made object to reach the
miles (about 18 billion kilo- space between stars.
meters) from Earth. Associated Press
It’s trailing twin Voyager 1, Scientists know that Voyag- ing the spacecraft was now
which reached interstellar er 2 has left the sun’s influ- in between the stars. One
space in 2012 and is now ence because of four dif- of the instruments mea-
13 billion miles (21 billion ferent instruments that are sures solar plasma and this
kilometers) from Earth. In- measuring solar particles is the first time NASA saw a
terstellar space is the vast and different types of rays. drop in that key instrument;
mostly emptiness between They showed a dramatic the same instrument wasn’t
star systems. change on Nov. 5, indicat- working on Voyager 1.q