Industrial noise
disrupts plants
effects on animals alter
dispersal of seeds, pollen
By Susan Milius
Noise pollution can stomp its sound-print on plants, a study of motors chugging in a Western forest finds.
Of course, plants don’t have ears, but
birds and other animals hear the throb
of humankind’s machines. The uproar
drives away some species and sometimes
encourages others, swapping their various influences on plants, says Clinton
Francis of the National Evolutionary
Synthesis Center in Durham, N.C.
Around noisy gas wells in a northwestern New Mexico woodland, Francis and
his colleagues found that the reshuffling
of birds and small mammals changed
the odds of success for crucial steps in
plant reproduction. Hummingbird pollination, important for certain wildflowers, increased. Yet birds likely to spread
around pine seeds without eating all of
them largely gave way to mice that eat
more of their seed cache, Francis and his
colleagues report online March 21 in the
Proceedings of the Royal Society B.
The new experiments are the first to
show that sounds affect the structure
of a whole biological community, says
behavioral ecologist John Swaddle at
the College of William and Mary in Williamsburg, Va. With such cascading consequences, “whole ecosystems can be
restructured by noise pollution,” he says.
The automated gas wells create a natural experimental setup for separating
the effects of noise from other quirks of
landscapes, Francis says. About half the
wells need compressors that run day and
night and blast such a din that anyone
working up close needs ear protection.
The rest of the wells don’t use compressors but have the same basic setup.
Earlier work concluded that noise
36
decibels
noise level at flower
sites 125 meters
from quiet gas wells
49
decibels
noise level at flower
sites 125 meters
from noisy gas wells
Black-chinned hummingbirds (left) are more common near noisy gas wells than near
wells with quieter equipment. Tests with fake flowers (right) reveal more humming-
bird pollination near noisy wells, perhaps because fewer predators lurk there.
matters for bird nesting. About the
same number of birds nested around
both roaring and quieter wells, but
quieter neighborhoods had a greater
variety of species. Western scrub jays
hardly showed up around the noisy
sites, possibly because noise masked
the jays’ hunting cues. But house finches
and black-chinned hummingbirds were
more common there, perhaps avoiding
noise-averse predators.
Deception aids crayfish fighters
smaller of two claws doesn’t always pack less of a punch
By Rebecca Cheung
When it comes to male crayfish, not all
claws are created equal. In these crustaceans, the left and right claws might be
very different sizes — and the larger one
isn’t necessarily stronger, researchers
report online March 14 in Biology Letters .
This deceptiveness could help crayfish
bluff or trick an opponent during a fight,
says study coauthor Robbie Wilson, a
Clashing male crayfish size up their
adversary’s claws, but a bigger claw
doesn’t necessarily mean more muscle.
biologist at the University of Queensland
in Brisbane, Australia. What’s more, the
findings suggest that within a species,
“dishonesty occurs in nature more commonly than we expect,” Wilson says.
During a clash, a male crayfish sizes
up his opponent when deciding to fight
or flee. Previously, scientists found that
stronger, smaller-clawed crayfish would
back down from weaker, larger-clawed
opponents. So some bluffing clearly
occurred between these crustaceans.
In the new work, Wilson and Michael
Angilletta Jr. of Arizona State University
compared claw size and strength in the
slender crayfish Cherax dispar. In some
cases, one of an animal’s two equally sized
claws was much stronger. In other cases,
a larger claw was weaker than the smaller
limb. This misleading size and strength in
the two claws might provide an advantage
during combat, says Wilson.
