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.
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.
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)
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.
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.
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.
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:
In one direction, it flows west to the Allegheny River, down the Mississippi watershed and into the Gulf of Mexico.
Or it flows north to the Genesee River, Lake Ontario, the Saint Lawrence watershed and into the north Atlantic.
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)
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.
(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.
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 …
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.
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.)