Category Archives: Musings & News

On Vortex Street

Clouds on the lee side of Guadalupe Island, Mexico, 24 May 2017 (image from NASA’s Landsat satellite)

What do these photos and video have in common?

Smokestacks at Proserpine Mill, Jan 2012 (photo from Wikimedia Commons)

humming sound of wind in the wires (turn up speakers)

Answer: All three indicate the presence of — or potential for — a von Kármán vortex street.

When you’re in the neighborhood, this street is a fluid dynamic place. Learn more in this vintage article as we go Walking Down Vortex Street. (click the link)

(photos NASA and Wikimedia Commons; click on the captions to see the originals. video by Megan Lewis on YouTube)

In The End, The Sea Will Win

American oystercatcher in flight, New Jersey (photo by Tony Bruno)

Sunday, 12 January 2020

Tomorrow the New Jersey legislature will consider a bill that will either protect or destroy 15 acres of state park land where a neighboring golf course wants to build 3 golf holes. The showdown between those who love public parks and nature versus extremely rich developers is well described in the New York Times: Golf Club for the 1 Percent Wants to Seize a Migratory Bird Habitat.

I don’t know how the fight will play out in human terms but I’m sure of one thing. In the end the sea will win.

Caven Point Natural Area is a sandy peninsula on the Hudson River in Jersey City, NJ, a migratory bird stopover and nesting site so sensitive that the area is closed April through September to leave the birds in peace. American oystercatchers, shown above, are some of the cool birds you can see there.

Though it’s part of Liberty State Park, Caven Point Natural Area (yellow circle) is not contiguous to it.

Map of Liberty State Park (map from New Jersey State Parks)

Its adjacent neighbor is the very exclusive Liberty National Golf Club whose seawall borders the footpath to the site.

Hudson River Waterfront Walkway to Caven Point. Liberty National Golf Club seawall is on the right (photo by Bill Benson via Flickr Creative Commons license)

Liberty National Golf Club is one of the most exclusive golf courses in the US with an initiation fee of nearly half a million dollars. The course has breathtaking views of the Manhattan skyline which you may have seen on television last August when Liberty National hosted the PGA TOUR’s FedEx Cup Playoffs from August 6–11, 2019. This photo, uploaded by Redi-Rock International in 2015, gives you an idea of the view.

Scene from Liberty National Golf Club (photo by Redi-Rock International via Flickr Creative Commons license)

To us humans, Nature is the backdrop to the protests, letter writing, legislation and legal battles, but Nature will be the foreground in the years ahead. Climate change and sea level rise will engulf Caven Point and part of the existing golf course. It is already happening.

This map of the Caven Point area from NOAA’s Sea Level Rise Viewer shows red where the highest high tides inundate the land today. This doesn’t include the 5-foot wall of water that washed over the area during Hurricane Sandy in 2012.

Caven Point sea level at high high tide (map from NOAA Sea Level Rise Viewer)

If the ocean rises 3 feet, as predicted for this century, Caven Point will become an island, ponds on the existing golf course will overflow (green) and the end of Liberty National’s parking lot near the clubhouse will be underwater every day (green).

Inundation from 3-foot sea level rise (map from NOAA Sea Level Rise Viewer)

Even if it doesn’t rise three feet very soon …

“Nobody’s debating that sea-level rise is happening. It’s back to how much, how fast,” Helen Amanda Fricker, a glaciologist at Scripps Institution of Oceanography, told me. Even the most optimistic scientists have recently increased their low-end estimates, she said.

from The Atlantic, 4 January 2019

In the end, the sea will win. In the meantime, save the land for the birds.

UPDATE on 14 JAN 2020: The New Jersey legislature failed to act on the bill & it was the last day of the legislative session so the bill is dead unless reintroduced in the next session. See Despite gaining senate support, Liberty State Park Protection Act dead for now.

(photo of American oystercatcher by Tony Bruno. Caven Point walkway by Bill Benson on Flickr, Liberty National Golf Course by Redi-Rock International on Flickr, maps from New Jersey State Parks and NOAA Sea Level Viewer; click on the captions to see the originals)

Science By The Seat Of Our Pants

screenshot from CalTech video: The Science of Booming Sands – 2015

For thousands of years people have known that certain sand dunes make a low humming sound, the musical note of G, E or F. It occurs when the sand is moving but you can force the sound if you slide downhill. Why does it hum?

A decade ago scientists at CalTech studied two humming sand dunes in California to answer that question. They found that for the sand to sing, the grains have to be all the same size, the dune must have a slope greater than 30 degrees and be over 120 feet tall, and the sand must be dried under the desert’s summer sun. It was very hot work.

The humming sound occurs naturally when the sand moves but that doesn’t happen on a predictable schedule so the CalTech team forced the sound. Dr. Melany Hunt explained,

Usually we would trigger it by having a number of people slide down the dune in unison. We always called it ‘Science by the seat of our pants.’

Learn about their study in this short video from CalTech or hear the sound as it’s being made in this vintage article: Singing Sand.

(screenshot from CalTech video: The Science of Booming Sands – 2015)

A Corvid Sweep

Ravens in flight (photo by John Johnston via Flickr Creative Commons license)
Sweep(noun): In sports, a sweep is a series in which a person or team wins all games.

During the Pittsburgh Christmas Bird Count (CBC) last Saturday I saw every member of the crow family that occurs in Pennsylvania. I had a Corvid Sweep in my own city neighborhood!

Twenty corvid species can be seen in the US. but Pennsylvania hosts only four: blue jay, American crow, fish crow, and common raven. Blue jays and American crows are common, but until this century ravens and fish crows were quite rare in Pittsburgh. This year’s CBC tallied 7 ravens and 10 fish crows in the 15-mile circle, swamped by the presence of 10,000 American crows. (*)

The ravens (Corvus corax) were a real surprise. A group of four circled up and played in the sky over Hazelwood Greenway. I heard them call as they landed on the tallest thing for miles around — the radio tower next to Calvary Cemetery. Woo hoo!

Fish crows (Corvus ossifragus) are probably under counted in Pittsburgh because they’re hard to identify. They look just like American crows though slightly smaller. The only reliable way to identify a fish crow is by its nasal voice. If he doesn’t speak we don’t know who he is.

For sheer spectacle, though, nothing beats the winter crow flock coming in to roost. Claire Stales and I counted 10,000 from the roof of a parking garage near Trees Hall and we know we under counted, perhaps by half. This year the flock didn’t pre-roost west of us and, because buildings block the view, we never saw the crows that stream in from the Allegheny Valley and Shadyside.

But we did stop by the area of Bellefield, Bayard and Bigelow where 3,000 to 4,000 crows spend the night. This year they’ve abandoned Pitt’s campus, only two blocks away, and I think I know why. On December 18 at 5:00pm I was counting crows flying from Schenley Park toward Pitt when I saw the new resident female peregrine, Morela, escort them away from campus. Aha!

Crows fly in to roost in Oakland (photo by Kate St. John)

Hooray for the Corvid Sweep!

(photos by John Johnston via Flickr and Kate St. John)

(*) preliminary count as of 12/29/2019, before all the data is in.

From Grief To Action

Red-winged blackbird, Point Pelee, Ontario, 2010 (photo from Wikimedia Commons)

Yesterday I shared a report on the stunning loss of North American birds. 29% have disappeared since 1970 with heavy losses in many of my favorite species including blackbirds, warblers and wood thrushes. We grieve as Silent Spring happens before our eyes.

Though the report was depressing there were two bright spots that provide hope and can guide us from grief to action. The report includes this happy news: Ducks increased 56% and raptors 200% thanks to our intervention.

Ring-necked ducks take off, March 2011 (photo by Steve Gosser)
Ring-necked ducks, March 2011 (photo by Steve Gosser)

Ducks were in such steep decline in the early 1900s that hunters banded together to reverse the trend. The main cause of decline was habitat loss — the disappearance of wetlands — so they worked to pass wetland protection laws in the U.S. and Canada and migratory duck protection in Mexico. People gave of their time and money to build wetland habitat for waterfowl, especially through Ducks Unlimited. Their effort paid off.

Female peregrine in flight, May 2016 (photo by Peter Bell)

Meanwhile, by 1970 peregrine falcons were extinct east of the Mississippi and bald eagle populations had crashed. The cause was a pesticide — DDT — that was outlawed in the U.S. in 1972. With Endangered Species Act protection and the work of recovery programs, peregrine falcons and bald eagles made a stunning come back.

The recent decline in North American birds has its root in the same problems we solved for ducks and raptors: habitat loss and pesticides. We solved it before, can do it again. We can turn our grief into action.

Our actions can be small scale or large — from our own backyards, to local schools and parks, to the national level.

On a personal scale, Cornell Lab of Ornithology suggests seven simple things. I’ll add two questions to think about: Do you treat your lawn? Do you ‘fog’ your backyard to keep mosquitoes away? Reducing insects means birds and nestlings starve.

On a local and national scale we can work to restore habitat and reduce pesticides through conservation organizations and our local Audubon and birding clubs (see list at end).

And finally, we can work to change attitudes toward nature and we can vote. Wetland protection and pesticide laws were key to saving ducks and raptors. Every level of government — from school board to nation — makes decisions that affect birds.

After an interval of grief, we’ll have a lot to do. We can do it. We just have to try.

Red-winged blackbird flock, Kansas, 2006 (photo from Wikimedia Commons)

(red-winged blackbird photos from Wikimedia Commons; 7 Simple Things from Cornell Lab of Ornithology; click on the captions to see the originals. Ring-necked ducks by Steve Gosser, peregrine falcon by Peter Bell)

p.s. Pittsburghers, here are some land and bird conservation organizations, mostly local:

29% of Our Birds Have Vanished

In the past several years my friends and I have noticed it. We expect to see a lot of birds at our feeders and on migration but something has gone wrong. We rarely see so many, sometimes almost none. There are fewer birds than there used to be.

The truth is worse than we thought. A report published in Science on 19 September 2019, shows that the bird population of North America has declined by 2.9 billion birds since 1970. Half of that decline occurred in the last 10 years(*). Indeed, we have seen Silent Spring happening before our eyes.

The declines are uneven across species and regions. Grassland species have been hit the hardest with more than half gone. Boreal forests have lost a third. 617 million wood warblers are gone.

The research team, led by Kenneth V. Rosenberg of Cornell University, analyzed many data sets including Breeding Bird Surveys, Christmas Bird Counts and US Fish and Wildlife Surveys. The most poignant proof came from a non-human counter — radar data of nocturnal spring migration. Across the U.S. from 2007 to 2017 weather radar saw a 14% reduction in our bird population.

The heaviest losses occurred in the Atlantic and Mississippi flyways (blue and green on map).

Migration flyways map from Melissa Mayntz at The Spruce
Migration flyways map, Melissa Mayntz at The Spruce

Pittsburgh’s radar station was in the top 20% of locations that lost birds.

Pittsburgh’s National Weather Service radar in Moon Twp PA (photo from

Here’s just a sample of the decline in species since 1970:

  • 50% of red-winged blackbirds have vanished,
  • 92% of blackpoll warblers have disappeared since 1966,
  • 70% of chimney swifts,
  • 60% of wood thrushes,
  • 25% of blue jays (Have You Seen Any Blue Jays Lately?),
  • 81% of house sparrows and 49% of starlings. Though these two species are invasive their demise is an indication of how serious this is.

The reasons for decline are across the board including increased use of pesticides, habitat loss, collisions with windows, cats and many more. For instance, neonicotinoid pesticides, deadly to bees, are weakening songbirds so they delay migration or fail to complete it. Logging and fires in the boreal forest and in Central and South America have eliminated warbler habitat on both breeding and wintering grounds.

Birders have noticed the decline because it recently accelerated. Half the birds disappeared in the first 40 years. The other half vanished in the last decade.

Right now some of us are grieving, an ecological grief for the loss of birds and the prospect of a bleak future.

But there are bright spots in the report that give us hope and a way forward. I’ll write about them tomorrow.

(Credits: slideshow images courtesy Cornell University Digital Press Kit, flyways map by Melissa Mayntz at The Spruce, photo of Pittsburgh NWS radar station from

Source material and additional information:

An Infectious Enthusiasm For Birds

Tony Bledsoe lecturing at Univ of Pittsburgh, approx 2006 (screenshot from video)

This week I was saddened to learn that Dr. Anthony Bledsoe passed away on Saturday September 14, 2019. His infectious enthusiasm for birds and behind the scenes advocacy will be sorely missed.

Tony Bledsoe was an instructor and lecturer at the University of Pittsburgh for 31 years and such an inspiring teacher that his students rated him “One of the best professors I’ve ever had.” In 2006 he won the Tina and David Bellet Teaching Excellence Award as Outstanding Undergraduate Teacher in Arts and Sciences at the University, voted by the students themselves.

Tony was a friend and a behind-the-scenes advocate for birds at the University of Pittsburgh. I first met him in 2001 when he offered to help me establish a peregrine nestbox at the Cathedral of Learning. Tony read my PABIRDS report about peregrines in courtship flight and knew there was no suitable location for them to nest. I wanted to install a nestbox but had no idea how to approach the University. Tony knew who to call. He worked behind the scenes to find people to champion the peregrines within the Administration. By February 2002, with Tony’s help, the nestbox was in place. Dorothy and Erie raised their first chicks that spring.

Dorothy with first nestling at the nestbox Tony Bledsoe helped establish at the Cathedral of Learning, Mothers’ Day 2002

Tony provided scientific background on peregrine behavior within the University and beyond. In March 2007, when Erie killed an intruder peregrine at the nestbox, he was interviewed by John Tierney of the New York Times for an article about the peregrine fight: Peregrine Smackdown: Stay Away From My Dorothy!

Bright specks in the beam, migrating birds swirl in Pitt’s Victory Lights, 7 Oct 2018, 11:05pm (photo by Kate St. John)

Last fall, as a member of the Board of the Audubon Society of Western Pennsylvania (ASWP), he worked behind the scenes to save migratory birds at the University of Pittsburgh. When he read my blog about the deadly attraction of Pitt’s Victory Lights, he called ASWP’s Executive Director Jim Bonner to urge this as a Board concern. Jim made connections so quickly that by that evening the University of Pittsburgh and ASWP were working together on the solution. (See Hooray! Good News For Birds!) This rapid response would not have been possible without Tony’s phone call.

Tony’s enthusiasm for science and for birds inspired those who knew him. The video below, probably from 2006, shows how committed he was to education and how he inspired students in every class.

Tony’s infectious enthusiasm will be sorely missed.

For more information, see his obituary here.


An object at rest tends to stay at rest (photo of Emmalina asleep by Kate St. John)

Today’s post was inspired by my cat Emmalina (Emmy) and a Twitter video.

My cat demonstrates the everyday meaning of “inertia” all the time. She has a tendency to rest and do nothing.

In fact the real meaning of inertia is the resistance of any physical object to any change in its motion, including a change in direction. It applies to both motion and rest.

Inertia in motion explains how our bodies move when we ride in a car.

  • When the car is going in a straight line at constant speed on a smooth road it feels like we aren’t moving. (No change in motion; no resistance to change)
  • Going around a curve, our bodies lean toward the outside of the curve. (Inertia resists change in direction)
  • When the car stops our bodies keep on moving ahead. (Inertia resists change in speed)

This Twitter video shows an object at rest — a dinosaur toy — staying at rest in mid air after the trampoline surface goes down. Then gravity takes over. Pretty cool.

Or this: The water in the balloon remains in its original shape for a moment after the balloon bursts.

Inertia: the water briefly stays in place (animation from Wikimedia Commons)

In everyday conversation “inertia” should probably mean resistance to change. My cat is good at that, too.

(photo of Emmalina by Kate St. John, dinosaur video from Twitter, balloon animation from Wikimedia Commons. Click on the links to see the originals)

96 Million Shade Balls

Early this week YouTube said to me, “Here’s a video you might like.” Maybe you will too.

Crazy as it looks, the Los Angeles Department of Water and Power (LADWP) is happy with the results since they covered their reservoir with 96 million black balls.

LADWP calls them “shade balls” but they used to be called “bird balls.” Yet there’s not a bird in sight. This 12-minute video from Veritasium explains it.

I’ve never seen shade balls in Pittsburgh but I can think of several reasons why:

  • We have much less sun. (fewer sun-induced chemical reactions)
  • Our climate is humid. (less evaporation)
  • Bromates are not the big problem here. (Alas, in Pittsburgh our problem is lead.)

But perhaps I’m missing something. Have you seen shade balls in Pittsburgh? Let me know.

(video from Veritasium on YouTube)

Why So Many Landslides?

After a rainy period or spring thaw in Pittsburgh we inevitably see devastating landslides on the news. Why does Pittsburgh have so many landslides and why are they associated with rain or moisture?

The problem is a combination of a particular bedrock with our steep hillsides. Where both are present the location is landslide prone, as shown on the City of Pittsburgh map below. (Click here to see the City’s interactive landslide-prone map and zoom in for details. Click here for the Allegheny County interactive landslide map.)

Landslide prone areas (screenshot from Pittsburgh GIS Data Download Page)

The house in the video above was inside a landslide zone on Semicir Street overlooking Riverview Park. Add water and … the house collapsed!

The bedrock at fault is Pittsburgh redbed, a claystone that disintegrates into smaller and smaller pieces if exposed to pressure when it’s wet. Redbed is usually under pressure because it’s underneath solid rock and overlying soil. Add water to a steep slope and you have a landslide.

This sandstone boulder on the Bridle Trail in Schenley Park was part of the escarpment above it until the redbed layer beneath it gave way.

An old landslide in Schenley Park on the Bridle Trail, July 2019 (photo by Kate St. John)

Here’s a future landslide on the Lower Panther Hollow Trail. This sandstone boulder, high above my head, will fall some day because the slow drip of water over the boulder has disintegrated the underlying redbed. Notice the reddish crumbled stones.

Sandstone boulder is undercut, a landslide waiting to happen at Lower Panther Hollow Trail, Schenley Park, July 2019 (photo by Kate St. John)

I had read that Pittsburgh redbed disintegrates when wet but I wanted to see for myself so I gathered some redbed rocks and ran an experiment.

Thousands of years ago these small crumbles were a much bigger solid rock but water had already acted on them. Will the crumbles disintegrate in the presence of water and pressure? I kept some rocks dry and soaked others for a day. Here’s my experiment.

Add water and pressure to Pittsburgh redbed claystone and … Watch out below!

p.s. For a really spectacular landslide, check out what happened to Route 30 in East Pittsburgh in April 2018.

(photos and redbed experiment by Kate St. John, house collapse video embedded from WTAE Pittsburgh on YouTube, map from Pittsburgh GIS Data)