Panther Hollow Lake Found Empty Last Friday

Schenley Park
Panther Hollow Lake bottom exposed, 23 June 2023, 8:38am (photo by Kate St. John)

27 June 2023

On my Friday morning walk in Schenley Park (23 June 2023) the first thing I noticed from the Upper Trail was that Panther Hollow Lake looked really odd. When I got down to the edge I found out why. The lake had drained out, leaving half of it a sea of mud.

Panther Hollow Lake was built in 1892 by damming Panther Hollow Run and directing its outflow to a sewer pipe containing its original drainage, Four Mile Run, plus sewage. Last week something went wrong at the outflow point and the lake emptied.

Panther Hollow Lake, drained out at this outflow point, 23 June 2023, 8:56am (photo by Kate St. John)

Within 15 minutes of my Friday call to Pittsburgh 311, employees from two City Departments arrived on the scene. By mid-morning the Department of Public Works and Pittsburgh Water and Sewer Authority were working to fix the outflow.

DPW at Panther Hollow Lake outflow awaiting PWSA, 23 June 2023, 10:15am (photo by Kate St. John)

Today (27 June) Panther Hollow Lake is probably filling again but I’m out of town and haven’t had a chance to see it. If you visit the lake this week, leave a comment to let me know how it looks.

Meanwhile, this episode does not fix Panther Hollow Lake’s underlying problems of summer algae blooms and its unnatural concrete edge that prohibits lakeside vegetation. The algae blooms in part because the lake is shallow. The lake is shallow because it’s passing through the normal life cycle of a lake, illustrated in this diagram from NHLakes: The Life of a Lake.

diagram from The Life of a Lake at NHLakes.org

Once formed, lakes do not stay the same. Like people, they go through different life stages—youth, maturity, old age, and death. All lakes, even the largest, slowly disappear as their basins fill with sediment and plant material. The natural aging of a lake happens very slowly, over the course of hundreds and even thousands of years. But with human influence, it can take only decades.

… Eventually, the lake becomes a marsh, bog, or swamp. At this point, the drying-up process slows down dramatically; limnologists aren’t sure why. Eventually, the lake becomes dry land.

— The Life Cycle of Lakes, National Geographic

At this point eutrophic Panther Hollow Lake is “old” and somewhat like a marsh, a state that can last a long time without much change. But the lake’s 130 year history is filled with human intervention, from construction in 1892, through two “renovations” (1909 and 1957), and plans made in 2010-2016 to renovate again. Those plans fell through last November and put Panther Hollow Lake on hold.

Last Friday’s drain-out will likely restart the planning process. Meanwhile, the marsh attracted two rare birds in late April (American bittern and sora) and still has nesting red-winged blackbirds. On Friday the remaining “puddle” at the deep end held two Canada geese and a great blue heron, both unbothered by low water.

Two Canada geese and a great blue heron are not bothered by low water, 23 June 2023 (photo by Kate St. John)

Curious about the life stages of a lake? See:

(photos by Kate St. John, diagram courtesy nhlakes.org)

Duck Hollow Outing, Sun July 2

Books & Events
Spotted knapweed with a metallic green bug, early July 2013 (photo by Kate St. John)

26 June 2023

Join me this coming Sunday for a bird and nature walk at:

Duck Hollow and the Lower Nine Mile Run Trail — 2 July 2023, 8:30am to 10:30am.

Meet at Duck Hollow parking lot at the end of Old Browns Hill Road.

We’ll see flightless Canada geese, swallows over the river, busy birds with young, midsummer flowers, and insects like this metallic-green bug on spotted knapweed. I’m hoping for an indigo bunting.

Dress for the weather and wear comfortable walking shoes. Bring binoculars, field guides and a scope for river watching if you have them. Don’t forget to bring water, sunscreen and a hat.

As of this moment, Scattered Thunderstorms are predicted for 2 July but we all know that could change for the better or worse so check the Events page before you come in case this outing is canceled for thunder or heavy downpours.

Hope to see you there.

p.s. This July has five Sundays so the next outing will be on Sunday 30 July.

(photo by Kate St. John)

Listen For Merlins Nesting Near You

Birds of Prey, Nesting & Courtship
Merlin family at Chatham University, Pittsburgh, PA, July 2022 (photo by Malcolm Kurtz)

25 June 2023

Last year Malcolm Kurtz found the first recorded merlin nest in Allegheny County when he heard them on Chatham University’s campus. They were easy to find because merlins are extremely vocal during the breeding season, especially late June through July when their young beg loudly. If you recognize the sound you may discover merlins nesting near you. In Pennsylvania this is a very big deal and Don Nixon, who tracks Pennsylvania’s merlins, wants to know about it.

Merlins (Falco columbarius) are small, streaky, dark, very fast falcons about the size of pigeons who, after the DDT crash, did not nest in Pennsylvania for over 30 years. When they returned they chose old unmodified crow or hawk nests in conifers in forests, cities, residential areas, school yards, parks, cemeteries, and golf courses.

Don Nixon has seen merlin numbers grow quickly in recent years and writes:

  • We now have over 100 documented merlin nests across Pennsylvania since 2006.
  • Nest sites stretch from a repeatedly used area at Promised Land State Park in the Poconos to a golf course in Somerset.
  • Nests have been reported in 24 of Pennsylvania’s 67 counties.
  • Counties reporting nests for the first time in 2022 include Allegheny (Malcom’s nest), Blair, Cameron, Clarion, Columbiana and Somerset. 
  • This year Lackawanna County is already reporting its first nest.

Don publishes an annual PA merlin map after the breeding season, 2022 shown below. The dots appear clustered because there are few observers.

Pennsylvania merlin nests in 2022 (map from Don Nixon)

Since merlins don’t use the same nest site in consecutive years these dots don’t tell you where to find merlins this year. Instead you’ll have to listen for them. The two most common calls, described by Birds of the World, are:

  • Ki-Ki-Kee (Kek-Kek-Kek) given in courtship displays, territorial or other aggressive encounters,
  • Food Begging Whine: a monotonous call, given by female soliciting food transfers from male. Sometimes given after copulation. Also given by nestlings but softer and quicker.

Here are three examples:

Alarm near the nest, Xeno Canto 666137:

Female calling after mating with male, Xeno Canto 642023:

Adults and begging juvenile, Xeno Canto 583041:

If you hear these sounds look for merlins. If you heard them in Pennsylvania, Don Nixon wants to hear from you. Add your own dot to the PA Merlin Map. Contact Don at:

Don Nixon
1009 Green Glen Drive, DuBois, PA  15801
814-661-5944 (cell)
pamerlins@gmail.com

Now’s the time to listen for merlins. Maybe you’ll find a nest!

(photo by Malcolm Kurtz, map from Don Nixon)

Two Kinds of Mullein

Phenology, Plants & Fungi
Common mullein in bloom, Aspinwall, 21 July 2021 (photo by Kate St. John)

24 June 2023

Two kinds of mullein are blooming now in western Pennsylvania. Both are native to Eurasia and northern Africa and are listed as invasive in some states, but not in Pennsylvania.

Common mullein (Verbascum thapsus) is hard to miss in late June, standing 5-6 feet tall with a spike of yellow flowers. This hairy biennial plant spends its first year as a rosette of fuzzy basal leaves, similar to the early stage of lamb’s-ear.

Basal rosette of common mullein leaves, April 2016 (photo by Kate St. John)

In the second year it sends up a tall shoot topped by a flower spike.

Common mullein, Ohio River Trail, Pittsburgh, 18 June 2023 (photo by Kate St. John)

As the spikes go to seed in late July you can see why people used these plants as torches.

Common mullein by the river, Pittsburgh, 23 July 2017 (photo by Kate St. John)

Moth mullein (Verbascum blattaria), like common mullein, is also biennial but its flowers are prettier and more delicate.

Moth mullein in bloom, 25 July 2015 (photo by Kate St. John)

The basal leaves are hardly noticeable because the flowers draw so much attention.

Moth mullein basal leaves (photo by Bruce Ackley, Ohio State University via Bugwood.org)

The plant blooms from the bottom up …

Moth mullein, 12 June 2021 (photo by Kate St. John)

… and goes to seed in the same direction. Each seed pod looks like a ball with a string on top.

Moth mullein seed pod, 14 July 2019 (photo by Kate St. John)

Other than its beauty, moth mullein has an unexpected benefit. According to Wikipedia, it has “long been known to be an effective cockroach repellent, and it’s species name blattaria is actually derived from the Latin word for cockroach, blatta.”

Torches and cockroach repellent. Something to think of when you see these two mulleins.

(photo credits are in the captions)

Deep Sea Headlights

Water and Shore
 Lights from the Hercules ROV, Mid-Atlantic Ridge, The Lost City Expedition, 2005 (photo from NOAA via Wikimedia Commons)

23 June 2023

While the media focused this week on the search for a missing tourist submersible that imploded on its way to the wreck of the Titanic, we saw underwater search footage illuminated by headlights. Beginning at the ocean’s twilight zone, 200-1000 meters below the surface, headlights are required because sunlight cannot reach that deep. In underwater darkness deep sea creatures use bioluminescence.

In 2005, for the first time, Japanese scientists filmed a Dana octopus squid (Taningia danae) and saw its “headlamps” or photophores on the tips of two tentacles, some of the largest such organs known to science and comparable in size to fists or lemons. It is so dark in this squid’s natural habitat, 240 to 940 meters below the surface, that scientists believe the lights are used to stun its prey.

Illustration of Dana octopus squid from Wikimedia Commons

In September 2015 NOAA’s ship Okeanos Explorer was roving the undersea world near Hawaii with a robotic submersible when two Taningia danae approached the robot and acted aggressively.

video embedded from Schurel Video on YouTube

Were the squid annoyed by the man-made headlights?

Maybe they thought the headlights were the signal of a competitor.

(photo and video credits are in the captions; click on the captions to see the originals)

Pitt Peregrines Now and Then

Peregrines
Ecco and Carla bow at the Pitt peregrine nest, 21 June 2023 (photo from the National Aviary falconcam at Univ of Pittsburgh)

22 June 2023

This morning just after dawn I saw a peregrine fly by my window carrying prey to the Cathedral of Learning. I’m sure it was Ecco bringing breakfast to Carla. The pair is “in tune” as if it was nesting season. Ecco supplies Carla’s food and they bow at the nest several times a day, but I know there will be no eggs at the Cathedral of Learning this year. It’s too late to raise a peregrine family.

Today on Throwback Thursday I looked back seven years to find that the blog was All Peregrines All The Time in 2016. In this trip down memory lane, you might remember a few of these incidents from that June.

At the Cathedral of Learning in 2016, the peregrine pair was Hope and Terzo with just one female nestling who fledged on 13 June. Click here to read about her adventures.

A moment of repose: Peregrine fledgling C1, 16 June 2016 (photo by Peter Bell)
A moment of repose: Peregrine fledgling C1, 16 June 2016 (photo by Peter Bell)

One week later a banded female peregrine showed up on camera at the Cathedral of Learning nest. It was Magnum from the Neville Island I-79 Bridge territory where she had already fledged two young. (Click here or on the video screenshot for the story.)

A few days later Magnum left Oakland, Hope and Terzo paired again, and their fledgling grew up and left town.

This year, by contrast, is very quiet. Fingers crossed for a good season next year.

(photos and videos from the National Aviary falconcam at Univ of Pittsburgh)

Speaking of the Tilted Earth

Weather & Sky
Sunrise on the summer solstice, Pittsburgh, 21 June 2023 (photo by Kate St. John)

Wednesday 21 June 2023

Two days ago we learned how humans are changing the tilt of the Earth(*). Today we celebrate the most important Tilted Earth Day in the northern hemisphere when the summer solstice occurs at 10:57am EDT and gives us the longest day.

Sunlight on Earth on the northern summer solstice (diagram from Wikimedia Commons)

Three years ago meteorologist Bill Kelly made this video at WJLA in Washington, DC explaining how the Earth’s tilt is the key to the solstice. Only one fact has changed: The solstice is on a different date and time. Sunrise, sunset, and day length are the same in DC today as they were on the solstice in 2020.

Bill Kelly video on YouTube

In Pittsburgh today the sun rose at 5:49am, we’ll have 15 hours, 3 minutes and 50 seconds of daylight, and the sun will set at 8:53pm. Thanks to the tilted Earth.

(*) p.s. How much have humans changed the tilt of the Earth? The study highlighted in Monday’s blog calculated that we’ve already moved it 80 cm (31.5?) in just 17 years (1993-2010). Click here to read more.

(photo and video credits: Click on the captions to see the originals)

Thunderstorms in Training

Weather & Sky
Thunderstorm (photo by “jcpjr” from Shutterstock.com)

Occasionally during the May-to-August storm season, the National Weather Service warns of flash flooding because of potential “training thunderstorms.”

Training thunderstorms? Are they getting in shape for a big competition? Are they practicing to be better thunderstorms? Are they learning from older, wiser storms?

No. “Training” in this case means the storms are lined up in a row, moving one after the other like railcars in a train. The Philadelphia Area Weather Book describes it:

Most of the year, thunderstorms, steered by speedy winds a few miles above the ground, move along quickly enough so that flooding is not a problem. But those high-altitude winds are typically much weaker in summer and, at times, nearly calm. When this happens, thunderstorms can sit over the same spot for hours. Even if the steering winds are not that lazy, flooding can still occur if the winds blow parallel to a line of storms. When that happens, one thunderstorm after another passes over the same location like railroad cars in a train passing over a track. Appropriately meteorologists call this process training.

— The Philadelphia Area Weather Book, 2002

From the ground we experience them as storm after storm and downpour after downpour, but on radar they look like a moving train seen from above.

Marked up radar image showing training thunderstorms (image from Wikimedia Commons)

When radar-watching meteorologists saw this phenomenon they turned the concept of “moving like a train” into an adjective describing thunderstorm behavior. The new use of an old word did not catch on. Though it’s been around at least 30 years it’s not in the dictionary.

definition of training from Google

And so when “training thunderstorms” occur, which is thankfully rare, weather forecasters must explain the term.

video about training thunderstorms from KHOU-TV on YouTube

Learn more about the complex cauldron of air that churns out training thunderstorms in Forbes Magazine: Thunderstorm Training Can Turn an Average Storm into a Flash Flood Emergency.

(photos by “jcpjr” from Shutterstock.com and from Wikimedia Commons, dictionary screenshot from Google)

Humans Are Changing the Tilt of the Earth

Musings & News, Weather & Sky
Windmill pumping groundwater in Texas (photo from Wikimedia Commons)

19 June 2023

Compared to the size of our planet we humans aren’t particularly large but with billions of us pumping groundwater we have changed the tilt of the Earth. Slightly.

The angle of Earth’s axial tilt varies over a period of 26,000 years (precession) from 22.1 to 24.5 degrees, but within that it wobbles due to sloshing liquids like molten lava, ocean currents, and massive air currents such as hurricanes.

This very short video shows the North Pole wandering as the axis wobbles.

video from climate.nasa.gov

Earth’s spin axis wobbles, its North Pole tracing out a roughly 10-meter-wide circle every year or so. The center of this wobble also drifts over the long term; lately, it has been tilting in the direction of Iceland by about 9 centimeters per year. …

Now, scientists have found that a significant amount of the polar drift results from human activity: pumping groundwater for drinking and irrigation.

— Science Magazine: Humanity’s groundwater pumping has altered Earth’s tilt

Local water abundance, on the surface and underground, changes a region’s gravitational pull. This principle was used by the GRACE and GRACE-FO satellites as they rode the “hills” and “valleys” of gravity and recorded the presence and absence of groundwater.

To find out what affected Earth’s axial tilt, Clark R. Wilson at the University of Texas at Austin and his colleagues built a model of polar wander factoring in all the sloshing over time, including changes to surface water. But the model was missing something.

When the researchers also put in 2150 gigatons of groundwater that hydrologic models estimate were pumped between 1993 and 2010, the predicted polar motion aligned much more closely with observations. Wilson and his colleagues conclude that the redistribution of that water weight to the world’s oceans has caused Earth’s poles to shift nearly 80 centimeters during that time, reported Thursday in Geophysical Research Letters.

— Science Magazine: Humanity’s groundwater pumping has altered Earth’s tilt

The GRACE satellites detected groundwater changes that produced this map. Notice how groundwater dropped in the U.S. Southeast and the Central Valley of California.

NASA GRACE data shows trends in global groundwater storage, 2003-2013 (map from NASA)

How did we pump so much groundwater? We used machines like these.

Groundwater pumping station at water facility (photo from Wikimedia Commons)

Watch the groundwater come and go in India 2002-2008 in this NASA video. (Click on the image to access the video.)

Groundwater depletion in India (video from NASA Goddard Space Flight Center)

Who knew that we could make the planet move!? 80 cm (31.5″) in just 17 years.

(photos from Wikimedia Commons, maps from NASA, click on the captions to see the originals)

American Kestrels Mysteriously Decline

Bird Anatomy, Birds of Prey
American kestrel at Madera Canyon, AZ (photo from Wikimedia Commons)

18 June 2023

When I began watching peregrine falcons 22 years ago, peregrines were endangered and our smallest falcon, the American kestrel, was doing just fine, but the tables have turned. Peregrines have fully recovered from extinction in eastern North America while kestrels have lost half their population and face an uncertain future. The New York Times described their plight this week in The Mystery of the Vanishing Kestrels: What’s Happening to This Flashy Falcon? Can we save this beautiful bird before it’s gone?

Pair of American kestrels in Colombia (photo from Wikimedia Commons)

American kestrels (Falco sparverius) range from Alaska to Tierra del Fuego and are the only “kestrel” in the Americas, but they aren’t true kestrels like those found in Europe and Africa. Instead, DNA tests have shown that our kestrel is closely related to the larger falcons of the Americas, including peregrines. Falco sparverius evolved to fill the kestrel niche.

Range map of American kestrel from Wikimedia Commons. purple=Year round, orange=Summer breeding, blue=Winter non-breeding

American kestrels are versatile birds. At home in grasslands, meadows, deserts, cities and suburbs, they eat grasshoppers, crickets, large flying insects, beetles, lizards, small rodents and small birds.

Kestrel eating a bug (photo from Wikimedia Commons)

Kestrels nest in cavities in buildings, trees, cliffs and nestboxes but more than half of their sites are unoccupied now in eastern North America. I’ve seen the decline first hand in Pittsburgh. A decade ago there were two kestrel nests within a few blocks of Downtown’s Third Avenue peregrines. Now there are none.

Dr. John Smallwood, a professor of biology at Montclair State University interviewed in the New York Times article, has monitored 100 kestrel nestboxes in New Jersey for nearly 30 years. The number of occupied nests at his sites peaked at 61 in 2002 and has dropped ever since.

What’s going wrong for kestrels? Are they out-competed for prey? Are they ingesting poison? What’s happening on their wintering grounds? Are insect declines affecting kestrels? Are neonicotinoid pesticides a factor? And what about the bigger questions of habitat and climate change?

Many kestrel experts think it’s a combination of causes. Dr. Smallwood agrees, but he still has a top suspect. “If I’m only allowed one word: grasshoppers.”

The one parameter that seems to be declining over time, researchers say, is survival of young birds in the summer.

… the thinking is that those juveniles may be more dependent on insect prey because it’s easier to catch.

— New York Times: The Mystery of the Vanishing Kestrels: What’s Happening to This Flashy Falcon?
Female American kestrel holding a cricket (photo from Wikimedia Commons)

I would not be surprised to learn that the kestrels’ decline is linked to the rapid insect decline in this century which was probably prompted by neonics. Neonicotinoids were first introduced in the 1990s but didn’t take off as a pesticide until the early 2000s.

Meanwhile a nationwide study funded by the USGS and the U.S. Fish and Wildlife Service is looking into the American kestrel’s mysterious decline. I hope they find the answer soon.

Read more at The Mystery of the Vanishing Kestrels: What’s Happening to This Flashy Falcon?

(photos and map from Wikimedia Commons, click on the captions to see the originals)