Archive for the 'Musings & News' Category

Oct 28 2014

From T-Rex To Hummingbirds

Chart of dinosaur-to-bird evolution (illustration by Steve Brusatte)

Ancient birds have a new family tree.

In a report last month in Current Biology researchers at University of Edinburgh and Swarthmore College analyzed 850 body features of 150 dinosaurs, then used statistical analysis to assemble a detailed family tree from dinosaurs to birds.

Interestingly, they found that the evolution of bird characteristics in dinosaurs was very gradual and non-linear.  Features like feathers, wings and wishbones appeared in many species over tens of millions of years so there is no “missing link” dinosaur line to the first bird.

“This process was so gradual that if you traveled back in time to the Jurassic, you’d find that the earliest birds looked indistinguishable from many other dinosaurs,” said Swarthmore statistician Stephen Wang.

And then, 150 million years ago the bird skeleton came together and bang! there was an explosion in species from the one-of-a-kind hoatzin to more than 350 species of hummingbirds.  According to Science Daily, this explosion “supports a controversial theory proposed in the 1940s that the emergence of new body shapes in groups of species could result in a surge in their evolution.”

Read more here in Science Daily about the family tree.

Most kids go through a dinosaur-loving phase.  Some of us fall in love with birds and never come out of it.  ;)

 

(diagram by Stephen L. Brusatte, University of Edinburgh. Click on the image to see the original.)

 

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Oct 13 2014

What If…?

Published by under Musings & News

Portraits: Christopher Columbus, Passenger pigeon (images from Wikimedia Commons)

This year’s remembrance of the passenger pigeon is, for me, inextricably linked to Christopher Columbus.

Last year I read a book that generated that association.  1491: New Revelations of the Americas Before Columbus describes what North America was like before and after Columbus’ arrival.

Before Columbus, the human population in the Americas was larger than Europe’s and the landscape, animals and birds were balanced by the pressure of so many people.  Europeans arrived and accidentally left behind pigs carrying human disease.  Native Americans, who had no immunity to European disease, encountered the free-range pigs and spread the plagues through human contact.

The Western Hemisphere suddenly lost 95% of its human population in only 150 years.  Remove the keystone species and you get some pretty weird results.  European settlers didn’t see the transformation so they thought what they found was normal including the endless forest, huge bison herds and billions of passenger pigeons.

So I wonder …

If Native Americans had not died off, would passenger pigeons have boomed at all?

If there hadn’t been so many passenger pigeons, would we have hunted them to extinction?

What if?

 

(Two photos from Wikimedia Commons: portrait of Christopher Columbus by Sebastiano del Piombo, 1519.  Digital painting of the extinct Passenger Pigeon Ectopistes migratorius by Tim Hough.)

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Oct 07 2014

Water Cuts Rock

Published by under Musings & News

Kiskiminetas River at Roaring Run near Apollo, PA (photo by Kate St. John)

Amazing as it seems none of the hills in the Pittsburgh Low Plateau were ever mountains.  They were all made by water cutting rock.

When dinosaurs roamed the earth, Pittsburgh was at the shore of a shallow inland sea to our west.  At the time our soil was composed of sandy beaches, mudflats and swamps. The sand became sandstone, the mud became shale, and the decayed swamp plants became coal.

No geologic events deformed our rocks.  To our east the Appalachians slammed into the edge of the plateau and pushed up the Allegheny Mountains.  To our north the retreat of the glaciers made the land rise in a bounce-back from the pressure release.  Our plateau remained essentially flat, tilting slightly to the south and west.  Indeed the rock layers in our area are horizontal.  You can see this at highway road cuts.

But Pittsburgh doesn’t look flat.

Water transformed us, cutting dendritic paths in the landscape as it drained to the inland sea (now the Gulf of Mexico). The paths became deep valleys.  When you stand in a valley you see hills.

Vegetation now hides what happened to the land. You see the hills but none of the water cuts as shown in this view of the Kiskiminetas (Kiski) River at the mouth of Roaring Run.

Take a short hike up Roaring Run and see what water can do.

Water cuts rick at Roaring Run, Armstrong County (photo by Kate St. John)

Here the creek is carving a notch in weak shale.  The valley walls are steep and narrow.  The notch is big enough to wade in.

Eventually Roaring Run may look like the Kiski with tree-covered hills.

It all comes from water cutting rock.

 

(photos by Kate St. John)

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Sep 15 2014

In Steep Decline

Published by under Musings & News

Herring Gull (photo by Shawn Collins)

Last week I learned something new.  Did you know that herring gulls are in steep decline?

On Thursday Cornell’s Lab of Ornithology published the 2014 State of the Birds Report in honor of Martha, the last living passenger pigeon who died 100 years ago this month.  The report heralds the great conservation successes of the past 100 years — bald eagles, wood ducks, Kirtland’s warbler, brown pelicans — and warns of species currently in decline that need our attention.

Especially interesting is the list of 33 common birds in steep decline.  According to the report, “These birds have lost more than half their global population. All of these species combined have lost hundreds of millions of breeding individuals over the past four decades.”  We know from the passenger pigeon’s experience that steep decline can quickly lead to extinction so these birds are the ones to help right now.

Many are those I’ve written about in the past — common nighthawks, snow buntings, rusty blackbirds, common grackles — but the herring gull was a real surprise.   How can this species be threatened when we see them everywhere at the shore and the mall?

It turns out that herring gulls nearly went extinct in the 1880’s because of market hunting but made a stunning comeback to 100,000 birds by the 1980’s, thanks in part to humans’ wasteful ways (coastal refuse dumps and fishing boat waste).  Then the tide started to turn.  78% of the herring gull population has disappeared in the last 40 years.  Who knew?

There are plenty of birds who need our help.  Click here for the full report.  We can do it!

And here’s the list of 33 Common Species in Steep Decline.  You’ll find some surprises.

 

(photo by Shawn Collins)

http://ebird.org/ebird/view/checklist?subID=S19786167#sthash.nJ6TklhP.dpuf

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Aug 27 2014

Birds *Are* Dinosaurs

Published by under Musings & News

Four-winged dinosaur, Changyuraptor yangi, discovered in China (illustration by Stephanie Abramowicz, NHM)

(illustration by Stephanie Abramowicz, NHM)

News broke in mid-July of a newly discovered dinosaur with four wings and a very long tail.  As a member of the Microraptoria clade, Changyuraptor yangi is unusual.

Microraptors had been characterized as 2.5 – 3 feet long weighing up to 2.2. pounds, but this one broke the mold.  Changyuraptor is four feet long with 30% of its length made up of foot-long feathers at the end of its tail.  The animal is “four-winged” because it has long feathers on all four limbs.  And it was heavy — probably 9 pounds — which is four to six times heavier than a peregrine falcon, more similar in weight to a male bald eagle.

Changyuraptor’s long tail showed that this non-avian dinosaur had good flight control.  If you watch a big (modern) bird coming in for a landing you’ll see it slow its air speed by pushing down its tail and holding its head high.  The July report in Nature Communications said this dino could do that too.  Unfortunately the feathers on the raptors forewings (arms) were not well preserved, so scientists can’t tell if it could take off from the ground or only glide from trees.

Though he could fly Changyuraptor yangi is non-avian in other respects.  He had teeth instead of a beak and bones in his tail.  But he was clearly a forerunner to birds.  If you ask someone who knows a lot about dinosaurs what he thinks of birds you get a very cool answer.

In a video from the Syndey Morning Herald (click on the illustration to see the video) science columnist Peter Spinks interviews two paleontologists, one in the studio and one on the phone.  He asks both of them, “Does this clinch the deal for you that dinosaurs were the precursors of birds?”

Both answer that the deal was clinched for them long ago.  And then the second paleontologist, Mikael Siversson, adds, ““Not only are birds descended from dinosaurs, but in fact birds are dinosaurs. They are highly specialized surviving dinosaurs.”

Woo hoo!

 

Read more here at Science Matters.

(illustration of Changyuraptor yangi by Stephanie Abramowicz, Natural History Museum of Los Angeles County)

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Jul 29 2014

Even Less Water Than We Thought

Colorado River water loss as seen at Lake Mead, Nevada (photo from US Bureau of Reclamation)

Rainfall in Pittsburgh is normal this year but out West they’re in their 14th year of drought with no end in sight.  This is starkly obvious at Lake Mead near Las Vegas where the water level has dropped 138 feet, leaving a “bathtub ring” of mineral deposits.

Three western states depend on Lake Mead for water and on its dam for electricity.  Since last October 4.2 million acre feet came into the lake but 7.9 million was withdrawn.  The lake has dropped 30 feet in the past five months alone.  As the water drops so does Hoover Dam’s generating capacity, putting the electric supply at risk too.

You’d think this problem could be fixed by controlling surface water consumption but it goes much deeper than that.

Back in January, I wrote about NASA’s GRACE satellite pair that measures groundwater from outer space (click here to read how it works).  Using nine years of GRACE data from the Colorado River Basin, University of California Irvine and NASA scientists made an alarming discovery.  From December 2004 to November 2013 the watershed lost 53 million acre-feet of water, an amount almost twice the size of Lake Mead.  More than 75% of that loss was from groundwater.  No one knows how much water is underground but it’s going fast.

When wells deplete groundwater, there are significant downstream consequences.  A 2012 study by Stanford Woods Institute found that overpumping can make the surface run dry.  Though surface water is carefully managed in the West, groundwater use is often poorly documented and barely managed — if at all.

Water loss at this scale affects every living thing.  Near Las Vegas the wetlands along Lake Mead are gone and so are the birds and animals that depended on them.

If the loss continues at this rate, humans may have to leave Las Vegas, too.

 

Read more about this study in Science Daily.

(photo of Lake Mead by U.S. Bureau of Reclamation)

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May 13 2014

A Last Look?

Olive-sided flycatcher (photo by Dominic Sherony via Wikimedia Commons)

On Sunday afternoon I saw an olive-sided flycatcher above the Sand Dunes Trail at Oak Openings Preserve, Swanton, Ohio.  I mention these specifics because he was only the second olive-sided flycatcher I’ve ever seen.  The first was 11 years ago at Raccoon Creek State Park on May 18, 2003.

Olive-sided flycatchers were always uncommon and now are increasingly rare.   In the past 40 years they’ve declined 3.3% per year, especially in western North America.  Where there used to be 100 individuals there are only 27 now.  They used to nest in Pennsylvania but no more.

Though he isn’t a flashy color he’s the peregrine falcon of flycatchers.  Perched high on a dead snag he scans the air for large flying insects, dives to catch them, and chases them down if they try to escape.  This bird is fast!   I watched him chase down bees or wasps, return to the perch and swallow each catch in a single gulp.  He rarely missed.  Then, just like a bird of prey, he ejected a pellet.

Olive-sided flycatchers breed at coniferous and boreal forest edges in the western U.S. and Canada and spend the winter in northwestern South America.  They happen to prefer burned or logged areas because the openings make for better flycatching.  The bird I found was in a location that had burned several years ago.

Pesticides, loss of bees and wasps, and habitat loss in North and South America have all contributed to the olive-sided flycatcher’s decline.  A reintroduction program like the one that restored the peregrine falcon can’t save this bird.   Instead we have to cooperate to preserve large tracts of his habitat.  Unfortunately, human cooperation on this scale is notoriously difficult to achieve.

This was my second look at an olive-sided flycatcher.  Will it be my last?

 

(photo by Dominic Sherony, Creative Commons license on Wikimedia Commons. Click on the image to see the original.)

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Feb 10 2014

Fresh Water At Risk

Published by under Musings & News

Aqueduct mapping tool screen shot at World Resources Institute

In the U.S. we tend to think that oil is the most precious and contested substance on earth because we hear about it in the media every day:  oil exploration, spills, oil prices and wars.  But if you think competition for oil is bad, water is worse.  Oil is a luxury, water is a basic necessity and clean fresh water is getting harder to find.

Last month the World Resources Institute (WRI) published Aqueduct, an interactive tool that measures and maps water risk.  From the maps I learned that water woes come in many flavors.

Some are naturally caused:   (This is not an exhaustive list!)

Others have man-made origins:

Water is very complicated,” says WRI.

Try their Aqueduct interactive tool to see where water is at risk.  You may be surprised at what you find in Wisconsin, Michigan and Cape Cod.

 

(screenshot of the Aqueduct mapping tool at World Resources Institute. Click on the image to use the tool)

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Feb 06 2014

Clean Your Bird Feeders

Published by under Musings & News

House finches in Phoenix, Arizona (photo by Kevin McGraw, Arizona State University)

In the depths of a bitter winter it’s a challenge to wade through ice and snow to refill the feeders and even more challenging to pull in those feeders and clean them.  Every day I put it off.  This message is for all of us who’ve been procrastinating.

A new study published this week in PLOS One has found a direct link between urbanization and avian infections.  The denser the human population, the sicker the birds.

Mathieu Giraudeau, Melanie Mousel, Stevan Earl, and Kevin McGraw studied canarypox and Coccidian infections in male house finches (Haemorhous mexicanus) in the Phoenix, Arizona metro area.  Like chicken pox, canarypox forms blisters on the skin.  Coccidiosis is caused by parasites in the intestinal tract, spread by infected feces or ingestion of infected tissue.  During the study, house finches with coccidiosis were found to be fatter but unable to absorb the nutrients they ate.

At each site where they trapped and diagnosed house finches, the researchers also noted the land use patterns and habitat.  Then they looked for correlations and found:  The denser the human population and the less natural the habitat, the higher the number and intensity of infections in the birds.

Why?

According to Science Daily: “Much like the spread of human disease in populated areas, urban centers can foster increases in multiple disease types in wild animals,” said Kevin McGraw, senior author of the study. “We are now investigating the mechanism underlying this observation.”

And from the PLOS One article: “Humans may facilitate infections in these birds via bird feeders (i.e. horizontal disease transmission due to unsanitary surfaces and/or elevations in host population densities) and/or via elevations in other forms of physiological stress (e.g. corticosterone, nutritional).”

Interestingly this photo from the study may hold a visual clue to the health of these two birds.  Male house finches should have red faces like the bird on the left.  Those with yellow have not absorbed enough carotene to produce red feathers.  Perhaps the yellow-faced bird has coccidiosis.

Bottom line:  Clean your bird feeders.

Read more here in Science Daily or the research article in PLOS One.

 

p.s. Click here for information on how to clean your bird feeders.

(photo by Kevin McGraw, Arizona State University)

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Jan 05 2014

Two Resins For Tomorrow

Published by under Musings & News,Trees

Frankincense from Yemen (photo from Wikimedia Commons)

Back in December when I wrote about amber, I learned about other tree resins important to humans.  Two of them are celebrated tomorrow on the traditional anniversary of the visit of the Magi who brought gold, frankincense and myrrh to the infant Jesus.

Frankincense, native to the Arabian peninsula and the Horn of Africa, is a hardened resin used in religious ceremonies around the world. It’s been traded for at least 5,000 years, burned as incense or steamed to release its essential oils.

The resin is produced by slashing the bark of trees in the Boswellia genus as often as two to three times a year.  Some say that Boswellia sacra produces the best.  Ironically frankincense trees are declining because agricultural pressure is clearing the land and the remaining trees can’t produce viable seeds if they’re slashed too often.

Frankincense tree, Boswellia sacra (photo from Wikimedia Commons)

 

Myrrh is the resin of thorny trees in the Commiphora genus, valued for its religious and medicinal uses.  Just like frankincense it’s produced by slashing the tree’s bark to make it ooze sap.

Myrrh (photo from Wikimedia Commons)

Commiphora myrrha is one of the species favored for myrrh and because it is native to Yemen, Somalia, Eritrea, and eastern Ethiopia Biblical scholars say that the wise man who gave that gift came from one of those countries.

Commiphora myrrha produces myrrh (image from Wikimedia Commons)

 

Tomorrow these two resins will be in the limelight, though frankincense and myrrh are used throughout the year.

 

(photos from Wikimedia Commons. Click on the images to see the originals)

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