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Shorter-winged swallows evolve around highways

Posted by on Mar. 22, 2013 at 8:13 AM
  • 17 Replies

Shorter-winged swallows evolve around highways
In survey along Nebraska roads, number of birds killed by cars has plummeted over 30 years
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ENLARGE
TRAFFIC DODGERS
Cliff swallows build small mud nests under bridges and highway overpasses, placing them at serious risk of becoming roadkill. Dodging cars may have favored a shift toward short, maneuverable wings.
C.R. Brown and M.B. Brown/Current Biology 2013

Crossing the road has gotten easier for cliff swallows. Over generations, the mortal threat of speeding cars may have shortened their wings.

Over the last 30 years, the number of cliff swallows killed along roads in southwestern Nebraska has plunged, and the birds’ average wing length has shrunk, researchers report March 18 in Current Biology.

The data are “jaw dropping,” says animal behaviorist Colleen Cassady St. Clair of the University of Alberta in Edmonton, who was not involved with the work. The results suggest that years of smacking into SUVs forced swallows to adapt to the road.

In the absence of roads, cliff swallows — sparrow-sized birds with orange rumps and white foreheads — tuck their nests under overhangs on cliff faces. But in the last few decades, many birds have traded ancestral homes for modern real estate — highway bridges and overpasses.

ENLARGE
Cliff swallow colonies can include thousands of nests like the ones pictured here on an interstate highway bridge in Nebraska. The birds’ roadkill rates have dropped over the last 30 years; shorter wings that help the swallows evade traffic may explain why.
C.R. Brown and M.B. Brown/Current Biology 2013

Cliff swallows can plaster thousands of cantaloupe-sized mud nests to the undersides of these structures, says study author Charles Brown of the University of Tulsa in Oklahoma. These colonies are less likely than cliff nests to be washed away in storms but come with a different risk: They perch near roads — and fast-moving traffic.

As graduate students in the 1980s, Brown and study coauthor Mary Bomberger Brown didn’t set out to study swallows’ adaptations to cars. They were interested in the birds’ social behavior. But because the team drove thousands of kilometers among colonies, they saw a lot of roadkill.

Every summer for the next 29 years, the team trekked to the colonies, counted nests and picked up dead birds. In total, the Browns gathered more than 2,000 swallows.

Starting in 1983, the researchers collected fewer birds killed by cars each year, until they found only four in 2012. And when Charles Brown measured preserved specimens’ wing lengths, he saw that, compared with the rest of the population, swallows that died on the road had wings that were a few millimeters longer.

A few millimeters — about the width of a Tic Tac — might seem like a small change, but for birds’ wings, “a little bit can make a big difference,” says evolutionary biologist Ronald Mumme of Allegheny College in Meadville, Pa.

Petite wings let birds take off quickly and maneuver deftly through the air. Like quail, which have short, rounded wings and can explode off the ground almost vertically, Brown says, swallows might be better served by short wings that help them whiz up and out of harm’s way.

He thinks the population’s shorter average wing lengths could help explain why roadkill numbers are going down. “It’s amazing what natural selection can do,” he says. 

The team ruled out other potential explanations, such as declining swallow populations or an increase in avian scavengers stealing carcasses. Still, Charles Brown says, factors other than wing length may also be involved. Cars may have killed off daredevil swallows, for example, leaving more cautious birds behind.

http://www.sciencenews.org/view/generic/id/349028/description/Shorter-winged_swallows_evolve_around_highways
by on Mar. 22, 2013 at 8:13 AM
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Replies (1-10):
jessilin0113
by Ruby Member on Mar. 22, 2013 at 8:48 AM

How cool.

Radarma
by Ruby Member on Mar. 22, 2013 at 9:13 AM
1 mom liked this
It is God's plan.

Jk

Hey in about 100 yrs we may no longer have pinky toes...adaptation is fascinating!

Altho I do hope we won't waddle much.
UpSheRises
by Platinum Member on Mar. 22, 2013 at 9:37 AM
1 mom liked this

Beyod cool...facinating. I LOVE stories of nature reclaiming habitats that we've ruined. It makes me feel hopeful for the future. 


Quoting jessilin0113:

How cool.


 

Mommy_of_Riley
by Jes on Mar. 22, 2013 at 10:03 AM
Mother Nature is awesome
Posted on CafeMom Mobile
krysstizzle
by on Mar. 22, 2013 at 10:26 AM

Pshaw, this kind of research is a huge waste of money, didn't you know? Some random blogger with no understanding of science said so in another thread! 

Blech.

Anyway, this is interesting. And makes sense. 

Very cool.

Billiejeens
by Ruby Member on Mar. 22, 2013 at 10:37 AM

 

Unless things change, in another 100 years we will have "evolved" to the point where we have lost the ability to ascertain right from wrong, and any natural instinct to be free.

Quoting Radarma:

It is God's plan.

Jk

Hey in about 100 yrs we may no longer have pinky toes...adaptation is fascinating!

Altho I do hope we won't waddle much.


 

krysstizzle
by on Mar. 22, 2013 at 10:41 AM

Your grasp of the complexies of the interplay between cultlure and biology, and the intricacies of psychology, as well as the scope of the human condition in history across time and space is simply astounding. 

Astounding in the lack of grasp, to be precise. 

Quoting Billiejeens:


Unless things change, in another 100 years we will have "evolved" to the point where we have lost the ability to ascertain right from wrong, and any natural instinct to be free.

Quoting Radarma:

It is God's plan.

Jk

Hey in about 100 yrs we may no longer have pinky toes...adaptation is fascinating!

Altho I do hope we won't waddle much.




Billiejeens
by Ruby Member on Mar. 22, 2013 at 10:45 AM

 

Complexities and culture

Quoting krysstizzle:

Your grasp of the complexies of the interplay between cultlure and biology, and the intricacies of psychology, as well as the scope of the human condition in history across time and space is simply astounding. 

Astounding in the lack of grasp, to be precise. 

Quoting Billiejeens:

 

Unless things change, in another 100 years we will have "evolved" to the point where we have lost the ability to ascertain right from wrong, and any natural instinct to be free.

Quoting Radarma:

It is God's plan.

Jk

Hey in about 100 yrs we may no longer have pinky toes...adaptation is fascinating!

Altho I do hope we won't waddle much.

 

 



 

krysstizzle
by on Mar. 22, 2013 at 10:48 AM

Awww, you're just completely disappointing me now. Resorting to harping on spelling errors? 

Too bad. You seem a little off your game, maybe more coffee?

P.S. I fixed it for you, so don't worry your little ol' head anymore.

Quoting Billiejeens:


Complexities and culture

Quoting krysstizzle:

Your grasp of the complexities of the interplay between cultlure and biology, and the intricacies of psychology, as well as the scope of the human condition in history across time and space is simply astounding. 

Astounding in the lack of grasp, to be precise. 

Quoting Billiejeens:


Unless things change, in another 100 years we will have "evolved" to the point where we have lost the ability to ascertain right from wrong, and any natural instinct to be free.

Quoting Radarma:

It is God's plan.

Jk

Hey in about 100 yrs we may no longer have pinky toes...adaptation is fascinating!

Altho I do hope we won't waddle much.







Billiejeens
by Ruby Member on Mar. 22, 2013 at 11:04 AM

 

I could be off my game, I dunno.

It simply seemed apropos to illuminate a post that clearly wanted to appear erudite and condescending, by correcting elementary school errors.

Quoting krysstizzle:

Awww, you're just completely disappointing me now. Resorting to harping on spelling errors? 

Too bad. You seem a little off your game, maybe more coffee?

P.S. I fixed it for you, so don't worry your little ol' head anymore.

Quoting Billiejeens:

 

Complexities and culture

Quoting krysstizzle:

Your grasp of the complexities of the interplay between cultlure and biology, and the intricacies of psychology, as well as the scope of the human condition in history across time and space is simply astounding. 

Astounding in the lack of grasp, to be precise. 

Quoting Billiejeens:

 

Unless things change, in another 100 years we will have "evolved" to the point where we have lost the ability to ascertain right from wrong, and any natural instinct to be free.

Quoting Radarma:

It is God's plan.

Jk

Hey in about 100 yrs we may no longer have pinky toes...adaptation is fascinating!

Altho I do hope we won't waddle much.

 

 


 

 



 

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