Archive for the 'Musings & News' Category

Feb 04 2013

Which Kills More Birds?

Published by under Musings & News

Windmill and Cat named Lilith (photos from Wikimedia Commons)

In case you missed it last week, the numbers have changed.

The Smithsonian Conservation Biology Institute and U.S. Fish and Wildlife Service developed a mathematical model, used data from 21 of the most rigorous cat-wildlife studies, and ran the numbers on cats.

The results were quite surprising.  2.4 billion birds are killed by cats every year in the U.S.  That’s two to four times the old statistics.

Compare this new data to other human-induced causes of bird mortality(*) and cats are now on top.

  • Cats: 2.4 billion
  • Windows: 1.0 billion
  • Power lines: 0.174 billion
  • Communication towers: 0.051 billion
  • Windmills: 0.0004 billion

So you can stop worrying about windmills.

If you want to save birds’ lives, keep your cat indoors.  I do.

 

Read more about this study including information on feral and pet cats in the New York Times.

(photo of windmill and a former stray cat named Lilith, both from Wikimedia Commons.  Click on the imbedded links to see the original photos)

 

(*) p.s. I’m not sure where habitat loss fits in now, but it has always been the leading cause of human-induced bird mortality.

p.p.s. I love both birds and cats.  Here are two posts about my beautiful indoor cat, Emmalina:  Mouse in the House and Animal, Vegetable.

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Jan 31 2013

Walking Down Vortex Street

I know almost nothing about fluid dynamics but my article about wingtip vortices two weeks ago piqued my interest in the subject.

Last weekend I learned about this amazing phenomenon, the von Kármán vortex street, animated above by Cesareo de La Rosa Siqueira.

Von Kármán vortex streets occur when a fluid flows past a stationary object and generates a long line of vortices that swirl in opposite directions.  The phenomenon was named for Theodore von Kármán, the man who described it, and is probably called a street because it looks like one.

We usually don’t see von Kármán vortex streets in the wind, but it’s important that engineers plan for them.  If a tall structure is uniformly straight the vortices can make it fall down.  Click here to read about a famous mistake.

On a small scale, von Kármán vortex streets make telephone wires sing in the wind.  On a large scale they’re visible from outer space when clouds blow past a tall island.

Here’s a picture taken from the space shuttle that shows cloud cover blowing past Rishiri Island, Japan.  When the wind encounters Mt. Rishiri the clouds form a von Kármán vortex street on the downwind side.

Pretty cool, huh?

There are more than twenty islands that reliably generate von Kármán vortex streets.  Click here to see more pictures from NASA.

(Vortex animation by Cesareo de La Rosa Siqueira via Wikimedia Commons.  Space shuttle photo from NASA via Wikimedia Commons. Click on the images to see the originals)

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Jan 01 2013

2012: The Year In Review

Nature was busy and interesting in 2012.  The weather was hot, stormy, dry, and sometimes wet. This brought exciting developments in the natural world.

Here’s a month-to-month roundup of my favorite high points with each photo linked to an article about the event.  Some link to my blog, others link to information on the web that I didn’t point out at the time.

 

  • January: Snowy owls were abundant in the northern U.S. into March. (photo by Shawn Collins)
  • February: The warm winter prompted a massive Canada goose migration on February 27 in eastern Pennsylvania, New York State and Ontario. (photo by Chuck Tague)
  • March:  Pittsburgh’s temperatures averaged 11.9 degrees above normal with some days 20 degrees above normal. Spring wildflowers bloomed 4-6 weeks early. (photo by Kate St. John)
  • April: There was a mass migration of Red Admiral butterflies in mid-April. (photo from Wikimedia Commons)
  • May: Birds who wintered in the U.S. migrated early but the warblers were right on time. (photo by Bobby Greene)
  • June: A new peregrine family was confirmed at Tarentum, PA when their nestlings appeared on the bridge. (photo by Steve Gosser)
  • July: Drought! (photo from NOAA NWS)
  • August: Every year I count nighthawks passing my home during their August migration.  Every year there are fewer.  Sadly, 2012 was no exception. (photo from Wikimedia Commons)
  • September: Arctic sea ice at its lowest extent ever. (photo from NOAA)
  • October: Hurricane Sandy brings unusual birds to western Pennsylvania. (photo by Jeff McDonald)

  • November: A surprising number of western hummingbirds visit Pennsylvania: rufous, calliope, Allen’s (photo by Scott Kinsey)
  • December: Evening grosbeaks visit Pennsylvania after decades of absence (photo by Marcy Cunkelman)

 

Happy New Year!

 

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Dec 17 2012

Singing Sand

Published by under Musings & News,Travel

I rarely spend time near sand dunes so I was amazed to learn that sand can sing.  In fact there are 35 places around the world where the dunes sing a low frequency hum in the bottom half of a cello’s range.

The droning happens naturally when the wind causes a sand avalanche.  People can force the song by pushing sand downhill.  The songs are well known but people have always wondered how and why they happen.

Some of the “how” is already known.

Singing dunes are crescent-shaped barchans with their backs to the wind and their horns pointing downwind.  The slipface is inside the crescent (downwind) with its surface at the angle of repose and a stationary layer beneath.

Experiments have shown the importance of the grains themselves.  If they’re spherical,  0.1 to 0.5 mm in diameter, and contain silica, they will sing in the lab when they slide down an incline.

This year physicists from Paris Diderot University discovered that grain size determines the tune.  They studied two dunes:  one in Morocco, one in Oman.   The Moroccan dune has grains 150-170 microns and emits a 105 hz sound (for musicians that’s near G-sharp two octaves below middle C).    The Omani dune has a variable grain size from 150 to 310 microns and its sound varies, too — from 90-150 hz (F-sharp to D).

Researchers took the Omani sand back to the lab and sifted it down to a nearly uniform size — 200 to 250 microns — and sent it down an incline.  Voilà.  The sand made a sound of 90 hz, close to the song of the Moroccan dune.  (Click here for more information about the study.)

What are the songs like?  In this video, filmed in Morocco, a man shows how he learned to make the sand sing.  Turn up your speakers and you’ll be able to hear a variety of sounds as he puts the sand through its paces.  The video is in French with subtitles, some of which are surprisingly translated as in the first sentence that says “Beware” when it means the less dangerous-sounding “Be aware.”

Thanks to science we’ve learned how the sand sings, but we still don’t know why.

(video from YouTube)

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Nov 26 2012

The Triple Divide

Published by under Musings & News

There’s a unique place in north central Pennsylvania at the top of three major watersheds. It’s called The Triple Divide.

When a raindrop falls there it can split three ways:

  1. In one direction, it flows west to the Allegheny River, down the Mississippi watershed and into the Gulf of Mexico.
  2. Or it flows north to the Genesee River, Lake Ontario, the Saint Lawrence watershed and into the north Atlantic.
  3. Or it flows southeast to Pine Creek, the Susquehanna River, Chesapeake Bay and the Atlantic Ocean.

The spot is in Genesee Twp, Potter County, Pennsylvania and is marked with the sign pictured above.

The location itself is unremarkable.  It’s not a big mountain, just a hill on the Allegheny Plateau near the New York state line.  It’s not even the highest point in Pennsylvania, but it spawns three major North American rivers:  the Mississippi, the St. Lawrence and the Susquehanna.

According to Dr. Robert N. Andersen at University of Wisconsin Eau Claire, “Triple divide points are ubiquitous in North America. Wherever there is a confluence of two streams there is a Triple Divide Point uniquely associated with the confluence. ”  Then he uses Pittsburgh’s confluence of the Allegheny and Monongahela Rivers to describe how to find a triple divide near us.

Beginning at the Point in Pittsburgh, trace the border of the Allegheny and Monongahela watersheds, moving upstream. Eventually you reach the place where the border ends.  At that point in Somerset County, east of Berlin, PA, is a triple divide that drains the Mississippi (via the Conemaugh and Youghiogeny), the North Branch of the Potomac, and the Susquehanna River (via the Juniata).

In the western U.S. there are triple divides that drain to both the Atlantic and Pacific.  And somewhere in Canada there’s an oceanic triple divide where a raindrop can split and flow to the Arctic, the Atlantic and the Pacific Oceans.

Follow a raindrop uphill and you’ll eventually find a triple divide.

(photo by Nicholas A. Tonelli on Wikimedia Commons. Click on the image to see the original and explore the location on Google Maps)

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Nov 20 2012

New Series

As usual, winter is a slow time for observing nature so my blog ideas are pretty thin. However, your encouragement on my Bird Anatomy series (20 Nov 2009 to 25 Feb 2011) has inspired me.

This Friday I’m going begin a new series called Tenth Page.

Though it’s loosely based on bird anatomy, Tenth Page is named for its subject matter.  My rule is that I must open Frank B. Gill’s Ornithology at a page number evenly divisible by 10.  Whatever is on that page will be fodder for a blog.

I’ve already checked all the tenth pages in my copy of the book and discovered that there are 3 blanks in the #10-series.  Aha!  Those will be wildcard subjects in which I can pick any old page I please.

And I won’t be predictable.  That would be boring.  Not 10, 20, 30 for me!  To keep myself interested I’m more likely to dip in at random and choose a tenth page that inspires me.

As a result, you won’t be able to guess my subject by reading the book — and neither will I.

Stay tuned for Tenth Page, coming this Friday.

(photo by See-ming Lee via Wikimedia Commons. Click on the image to see the original)

 

p.s. The photo above has a series of its own.  Taken by See-ming Lee at Vinegar Hill, New York, NY on 30 Dec 2007, it’s been posted to Wikimedia Commons for use in a series of blogs.  Click on the image to see the original photo and the list of blogs that have used it.  (Mine is there too.) Pretty cool!

p.p.s.  On the Bird-thday blog Peter and Stephen suggested I write about bird calls.  Be watching for bird calls sprinkled throughout the year.

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Nov 17 2012

Twilight

The days are short.  Twilight lingers.

Look up and listen to the darkening sky. Birds are on the move.

Crows and robins hurry to the roost.  Mourning doves race home at last light.

In the dark, the calls of geese encourage the flock on their long journey south.

(photo by Kate St. John)

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Nov 05 2012

The Whole World Is Hotter

 

The aftermath of Hurricane Sandy has reopened the topic of climate change.  Understandably the loudest voices come from those most affected, worried that this unusual storm is just the beginning of weather as usual on a warm planet.  Mayor Bloomberg of New York City was especially forthright.

How did we get such a strong hurricane so late in the season?  Why did it hit New Jersey, a place that’s had only one hurricane make landfall in 161 years of hurricane records?  (And that was in 1903.)

I learned the answers on WESA’s Allegheny Front on Saturday. Jeff Masters of the Weather Underground explained how hot ocean temperatures, prevailing winds, and high pressure centered over Greenland spawned the storm and steered it west.  (Click here to listen to the podcast.)

And though this individual storm can’t be pinned on climate change, its causes can.  The bottom line:  The whole world is hotter.

I hadn’t realized how much hotter and how rapidly the heat has increased until I watched this NASA animation of global surface temperature anomalies from 1880 to 2011.  Using the average global temperature in the mid-20th century as baseline, the map is colored blue when colder, orange when hotter.

Play the animation and see for yourself.

The train is rolling down the track.  (Perhaps it’s naive of me to say…) we could do something if we worked together politically and individually.  Meanwhile …

Old Charlie stole the handle
And the train won’t stop going
No way to slow down
.
Jethro Tull, Locomotive Breath, 1971

 

(animation from Goddard Multimedia, Goddard Space Flight Center, NASA, January 2012. Click here for more information)

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Oct 16 2012

Stumped

Published by under Musings & News,Trees

On Saturday while hiking with KTA in the Quehanna Wild Area we encountered an area of low vegetation and waist-high stumps. The only trees were those growing on top of stumps like the one pictured above. These were not live sprouts from the old stumps.  They were all different species.

It was an oddly barren place where tree regeneration was prevented unless the seedlings were nurtured in the core of a stump.  Here’s a Wikimedia photo by Ruhrfisch, taken in the same area.

 

The stumps were white pines, felled a hundred years ago.  State Foresters wondered how old the trees were when cut so they studied stumps with intact rings and discovered that they were all the same age –  200 years old.  Something had caused the area to regrow from scratch around 1700.

And they were all cut down at once at the turn of the last century.  Loggers clear-cut the entire state, each tree felled by two men with a cross-cut saw.  When they were done Pennsylvania looked like this (Tioga County, 1914):

 

It took a long time to recover from this damage.  The clear-cuts were ravaged by fires and erosion.  During the Great Depression some areas were replanted by the Civilian Conservation Corps.  In other places the land is still challenged.

And so we have a few barren reminders of the time when Pennsylvania exploited trees.

 

(photo of a tree growing on a stump by Kate St. John, other photos from Wikimedia Commons — click on those photos to see their originals)

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Oct 11 2012

How’s The Water?

Southwestern Pennsylvania’s waterways are scenic but in many places the water is bad.  This photo of the notch where Stony Run meets the Conemaugh River is a case in point.  See the orange tinge on the river bottom?  That’s bad water from abandoned mine drainage.

How prevalent is bad water in our area?

PittsburghTODAY recently published a map of non-attaining waterways in southwestern Pennsylvania.  Using Department of Environmental Protection data, the yellow lines show where water quality is compromised by abandoned mine drainage, agricultural runoff, sewage, and other causes.  The good water is blue.

Even in this thumbnail it’s easy to see that most of Allegheny County has bad surface water while most of Greene County is good.  The white space in the middle of Allegheny County is the City of Pittsburgh where the streams were buried as the city was built.  Click on the image to see the large map at PittsburghTODAY and drill in for a close-up.

The region’s bad water affects both our quality of life and the natural world.  Where water’s impaired aquatic life is poor, there are fewer fish, fewer birds, fewer mammals and bad water for us to drink.

So why is a lot of the map yellow?  It’s the legacy of coal.

During the heyday of deep mining in the early 1900′s Pennsylvania had weak or non-existent environmental laws and the state did not collect money from industry for clean up of the inevitable abandoned mine drainage.  Pennsylvania eventually enacted laws to prevent new damage but there’s no money to turn all of the yellow lines into blue.

One would hope that Pennsylvania learned from this history but in my opinion (not necessarily the opinion of WQED) our state has not.  Though damage is predictable from new industrial threats like Marcellus shale, the state still begins with weak laws, suffers new damage, then changes the laws after the damage is done.  (Click here for an example.)

So… how’s the water?
Sad.

(photo by Tim Vechter; map from PittsburghTODAY.org.  Click on the map to see the details)

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