“it’s amazing how little we still know about what’s down there.” —BenjAMIn VAn Mooy
Streetlamps turn bird duds into studs
By Susan Milius
Nesting near a streetlight
brightens the chances of philandering for young male birds.
Among birds called blue
tits residing in a forest on the
outskirts of Vienna, a yearling
male often fathers at least one
illicit chick if he nests within
50 meters of a lamppost, says
Bart Kempenaers of the Max
Planck Institute for Ornithology in Seewiesen, Germany.
In dark nests in the woods,
though, roving females generally overlook youngsters in favor of older males,
Kempenaers and his colleagues report
in a paper to be published in the Oct. 12
Current Biology.
The young males’ strange success may
come from a quirk linked to light pollution, the researchers suggest. Males near
night lighting start singing on average
Among blue tits, nesting near artificial lights
gets males singing earlier in the morning, giving
youngsters an edge in seducing a neighbor’s mate.
about three minutes earlier during the
dawn chorus of birdsong than naturally
lit birds do, the team found.
That doesn’t sound like a long time, but
a female taking a quick break from her
usual mate often visits a neighbor for only
a matter of minutes. Kempenaers’ previous work has shown that early serenading
has extra appeal for wandering females.
“Birds are very sensitive to light cues,”
says Michael Murphy of Portland State
University in Oregon. His own studies
of eastern kingbirds in North America
found that large males that sang early
were especially successful in fathering
chicks with other males’ mates.
From an otherwise unattractive male’s
point of view, streetlights must be great.
But Kempenaers says he doesn’t have
data on what will happen to the blue tit
population as a whole if artificial light
inspires many females to mate with
males that would normally be shunned.
Unlike noise or noxious chemicals,
light gets ignored because it’s “a gentle
form of pollution,” he says. But he predicts that its effects on reproduction are
widespread among species.
Streetlights affect blue tit females
too, the researchers found. In nests
near lights, females started to lay eggs
an average of 1. 5 days earlier.
A growing body of research documents
that artificial light is a disruptive pollutant for wildlife, says biogeographer Travis
Longcore, science director of The Urban
Wildlands Group in Los Angeles.
Warming throws
off cuckoo timing
birds fool a different species
mix when spring comes early
from top: frankDrebin/WikimeDia Commons; Csaba moskat
Anders Pape Møller of the University of
Paris South in Orsay. Cuckoo lineages are
known to specialize in fooling different
host species, including some that travel
far and some that stay close to home.
Now an increasing proportion of cuckoo
eggs end up in the nests of long-distance
migrants, Møller and his colleagues
report online September 15 in
Proceedings of the Royal Society B.
The trend is so strong,
Møller says, that he wouldn’t
be surprised if some cuckoo
lineages specializing in
short-distance migrants
face extinction in a matter
of decades.
In a warming climate,
cuckoo chicks menace a
different set of victims.
Changing migration patterns are driving the shift, Møller argues. Cuckoos fly
from Europe to sub-Saharan Africa for
winter. By the time they return in spring,
early warming has pushed year-round residents and short-distance travelers too far
along in their nesting to be good targets.
“Mistiming is a worldwide trend” with
climate change, says evolutionary ecologist Naomi Langmore of the
Australian National University in Canberra.
In parts of Europe where
spring temperatures have
risen the most, cuckoos have
targeted 73 species of short-distance migrants less, the
new study finds. In contrast,
the birds have focused more
on 49 species that migrate
longer distances.
