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50 YEARS AGO
550-year-old
seed sprouts
Bite a mouse in the back of the neck and
don’t let go. Now shake your head at a
frenzied 11 turns per second, as if saying
“No, no, no, no, no!”
You have just roughly imitated a hunting
loggerhead shrike (Lanius ludovicianus),
already considered one of North America’s
more ghoulish songbirds for the way it
impales its prey on thorns and barbed
wire.
Once the shrike hoists its prey onto
some prong, the bird will tug the carcass
downward “so it’s on there to stay,” says
vertebrate biologist Diego Sustaita. He
has witnessed a shrike, about the size of
a mockingbird, steadying a skewered frog
like a kabob for the grill. A bird might dig
in right away, keep the meal for later or
just let it sit around and demonstrate the
bird’s sex appeal (SN Online: 12/13/13).
Shrikes eat a lot of hefty insects, mixing
in rodents, lizards, snakes and even small
birds. The limit for impaling may be close
to the shrike’s own weight. A 1987 paper
reported on a shrike killing a cardinal not
UPDATE: Scientists continue
to test plants’ staying power,
growing plants from older
and older seeds. A roughly
1,300-year-old lotus seed
(SN: 8/31/02, p. 132) and then
a 2,000-year-old date palm
seed (SN: 7/5/08, p. 13) broke
the record for world’s oldest
viable seeds. Then in 2012,
Russian scientists grew a plant
from tissue frozen in Siberian
permafrost more than 30,000
years ago (SN: 4/7/12, p. 15).
These successes give hope to
seed bank programs that keep
plant species in cold storage
for future generations.
Excerpt from the
October 12, 1968
issue of Science News
I T’S ALIVE
These songbirds violently
fling and impale prey
A seed of the South America
herb achira (Canna sp.),
taken from an ancient
Indian necklace, has germinated, and the young plant
is growing well.… Carbon- 14
dating of bones at the site
sets the seeds’ age at about
550 years.… The plant from
the old seed appeared to
have a disturbed gravity
orientation, but is still
growing fairly normally.
and then struggling to lift off with its prize.
Recently, Sustaita got a rare chance to
video how the shrikes kill their prey.
Conservationists breed one loggerhead
shrike subspecies on San Clemente Island.
That’s about 120 kilometers west of
where Sustaita works at California State
University San Marcos. Sustaita set up
cameras around a caged feeding arena
and filmed shrikes, beak open, lunging
to catch dinner. “They’re aiming for the
prey’s neck,” he says.
That’s a very shrikey thing. Falcons and
hawks attack with their talons, but shrikes
evolved on the songbird branch of the bird
family tree — without such powerful
grips. Instead, shrikes land on their
feet and attack with their hooked
bills. “The bite happens at
the same time the feet hit
the ground,” Sustaita
says. If a mouse some-
how dodges, the shrike
pounces again, “feet first, mouth agape.”
Reading several decades of gruesome
shrike papers, Sustaita first thought the
real killing power came from the bird’s
bill, with bumps on the side, wedging
itself between neck vertebrae and biting
into the spine. Shrikes definitely bite, but
based on videos, Sustaita now proposes
that the shaking may help immobilize or
kill prey.
He and colleagues discovered that the
San Clemente shrikes fling their mouse
prey with a ferocity that reached six
times the acceleration of Earth’s gravity, the researchers report September
5 in Biology Letters. That’s about what a
person’s head would feel in a car crash at
about 3 to 16 kilometers per hour — “not
superfast,” Sustaita says, but enough to give
a person whiplash.
In a small mouse, such shaking looks
more damaging. Video analysis showed
that the mouse’s body and head were
twisting at different speeds. “Buckling,”
Sustaita calls it. Just how much damage
twisting does versus the neck bite remains
unclear. And there’s a whole other question: How does a shrike manage not to
shake its own brain to mush?
— Susan Milius
Watch a loggerhead shrike shake its prey at bit.ly/SN_shrike
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b
it o
t
n
evolved on the songbird branch of the bird
family tree — without such powerful
grips. Instead, shrikes land on their
feet and attack with their hooked
bills. “The bite happens at
the same time the feet hit A loggerhead shrike violently shakes small
vertebrate prey — such as
this dangling lizard.
