Watch Out for the Thagomizer!

Musings & News
Stegosaurus stenops, life reconstruction (image from Wikimedia Commons)

20 November 2023

For those who love dinosaurs, Stegosaurs are a recognizable favorite. These plant-eating armored animals wore rows of raised plates on their backs and spiky tails to protect them from the carnivores, especially the Allosaurus, a theropod ancestor of modern day birds.

When threatened, the Stegosaur swung its tail to batter its attacker with the spikes.

Stegosaurus tail detail, in the Royal Belgian Institute of Natural Sciences (photo from Wikimedia Commons)

This display at the Denver Museum of Nature and Science shows an Allosaur ready to bite a Stegosaur while two Stegosaur young run beneath her. Look closely in the background and you can see that the end of her tail — the spikes — are out of sight as they swing at the Alloasaur’s back.

Allosaur attacking Stegosaur, Denver Museum (photo from Wikimedia Commons)

When paleontologists were puzzled by a hole in this Allosaur vertebrae (at left) they figured out that a Stegosaur spike fits the hole (at right). Bone piercing bone in real time. Ouch!

Stegosaur tail spike pierced an Allosaur backbone (image from Wikimedia Commons)

The arrangement of the tail spikes had no name until “Kenneth Carpenter, then a paleontologist at the Denver Museum of Nature and Science, used the term when describing a fossil at the Society of Vertebrate Paleontology Annual Meeting in 1993.” — quote from Wikipedia.

The name came from a Far Side cartoon in 1982 when Gary Larson invented it as a joke. “Now, this end is called the thagomizer … after the late Thag Simmons.”

(fair -use-sized image from Wikipedia)

The name caught on and is now official.

A thagomizer is the distinctive arrangement of four spikes on the tails of stegosaurian dinosaurs. These spikes are believed to have been a defensive measure against predators.

— Wikipedia: Thagomizer account

The rest is history.

Watch out for that thagomizer!

(credits are in the captions. Tip of the hat to Jonathan Nadle who told me about the thagomizer.)

Where Do 10,000 – 20,000 Crows Go During The Day?

Crows & Ravens
Crows burst off a building as they prepare to roost in Oakland, 4 Nov 2016 (photo by Kate St.John)
Crows preparing to roost in Oakland, 4 Nov 2016 (photo by Kate St.John)

19 November 2023

As I wrote in Trying To Move The Crows last Thursday, Pittsburgh’s winter crow flock now numbers 6,000 to 10,000 and will build to 20,000 by the end of December. Their final flight to the roost every evening is so impressive that I included a video taken from my apartment window. Annie commented, “Your video is incredible! But where do the crows go during the day? And does morning look the same as they leave?”

In the morning crows leave the roost before sunrise but not nearly in the numbers I see at dusk, probably because most of them leave when it’s too dark to see Black Birds in a Black Sky. They are tiny silhouettes in this sunrise photo.

Sunrise with crows (tiny dots) heading east, 2 Nov 2023 (photo by Kate St. John)

The crows fan out in all directions and travel 6 to 50 miles one way — in stages — to find food. Flocks of 10 to 50 go to neighborhoods on trash day.

A crow on Garbage Day (photo by Joe Loong via Flickr Creative Commons license)

Photographer Sue Thompson said these crows were a day too early. It wasn’t Garbage Day yet.

Crows a day too early for Garbage Day (photo by Sue Thompson via Flickr Creative Commons license)

Some groups visit restaurants and shopping centers to explore the dumpsters.

Crows at a dumpster (photo by Edna Winti via Flickr Creative Commons license)

But for a really big feast crows go to landfills. There are at least seven large landfills within 30 miles of Pittsburgh’s crow roost. The nearest are 8-15 miles “as the crow flies.”

Landfills within 25 miles of Pittsburgh, PA (annotated Google map)

In mid-afternoon they start to head back in stages. At first there are just a few crows per flock.

Crows (photo from Wikimedia Commons)

They pause along the way in ever greater numbers as they combine into boisterous, noisy flocks. At the staging areas they meet new friends, greet neighbors, and exchange information about their day. It’s “The Bar Scene For Crows.”

Crows hanging out at a staging location (photo by Kate St. John)

The last stage is a only few blocks from the roost. Often they fly in after dark.

(video by Claire Staples, December 2018)

And the next morning they start all over again. If people rousted them from the prior night’s roost they’ll pick a new one and change the final staging area close to the new location. Crows can be flexible.

p.s. If you did not see the video taken from my apartment window at Trying To Move The Crows, check it out here:

Seen This Week: Red Sky and Leaves

Phenology

18 November 2023

After beautiful fall foliage in late October, the landscape faded to brown this week. All the colors were in the sky.

Friday’s sunrise was spectacular for good reason. “Red sky at morn” meant rain was on the way. Fortunately. Even with yesterday’s precipitation we are 6.81 inches below normal for the year.

Wednesday’s sunset was muted by comparison.

Sunset in Pittsburgh, 15 Nov 2023 (photo by Kate St. John)

By now the native trees in Pittsburgh are all brown or bare, so why are there still yellow and green leaves in Schenley Park?

Scene from Schenley Park Upper Trail, 17 Nov 2023 (photo by Kate St. John)

Invasive alien plants are tuned to the climate and daylight levels of their homeland. Those that originated further north than Pittsburgh, Japan for instance, see our November daylight as if it were October back home. Thus invasive honeysuckle bushes are still yellow-green and Norway maples still cling to their yellow leaves.

This virburnum retains its pinkish-green leaves for the same reason.

Pink-green leaves on alien viburnum, Schenley Park, 17 Nov 2023 (photo by Kate St. John)

The sun’s low angle showed off two Agaricaceae mushrooms among fallen leaves in Hays Woods.

Agaricaceae mushrooms at Hays Woods, 12 Nov 2023 (photo by Kate St. John)

Yesterday I found a tree on stilts in Schenley Park. This black locust germinated on top of a log on a rock. As the log deteriorated the roots found soil on either side of the rock. Years later there is a significant gap between the trunk and the ground.

Black locust tree “on stilts” because it grew on top of a rock, Schenley Park, 17 Nov 2023 (photo by Kate St. John)

(photos by Kate St. John)

Can You Spot the Peregrine?

Bird Behavior, Peregrines, Water and Shore
Stirring up the pigeons in Cleveland, 2017 (photo by Chad+Chris Saladin)

17 November 2023

Can you spot the peregrine?

When peregrines are hungry, the birds they’d like to eat flock tightly and move as fast as they can. The denser the flock the harder it is for the peregrine to pick out a solo bird to catch for dinner.

In the photo above pigeons are flying crosswise to avoid an oncoming peregrine. Can you spot the peregrine in the picture?

Dunlin (Calidris alpina) are masters of tight flocking and evasive maneuvers when threatened from the air. In the video below by Pacificnorthwestkate (@pnwkate) the dunlin move like a murmuration of starlings as a peregrine harasses them. Can you spot the peregrine?

embedded video by Pacificnorthwestkate on YouTube

Notice how the dunlin flock winks off and on in the video, dark at one moment then so white they disappear. In winter plumage dunlin have brown-gray backs and white bellies. The flock changes color as the birds turn in unison in the air.

Dunlin in winter plumage (photo from Wikimedia Common)

Last month I wrote about peregrines’ winter strategy for catching dunlin: Peregrines Are Just Tiring Them Out.

(credits are in the captions)

Trying To Move The Crows

Crows & Ravens
Crows roosting at Pitt by the light of the supermoon, 1 Dec 2017 (photo by Kate St. John)

16 November 2023

Crow news this week! from Phillip Rogers:

Hi all! There are hundreds (probably thousands?) of crows that roost every night outside the Cathedral of Learning at Pitt. Coming in at sunrise it feels like a scene straight out of Hitchcock’s The Birds movie. This evening I saw a man (facilities or groundskeeping employee?) using loud clapping and flashing lights to try to get the birds to leave (short video below). The sidewalks all around are littered with droppings, which is presumably why they want the birds gone.

— Phillip Rogers comment to PittsBirder Chat
Pitt tries to move the crows, 13 Nov 2023 (video by Phillip Rogers)

I remembered a similar episode 10 years ago when Pitt used bird distress sounds to scare the crows. Back then it worked …

The Crows Moved

… but crows are really smart. They soon figured out the recordings are fake and promptly ignored them.

By 2020 Pitt had to change tactics. Crows don’t like sudden loud noises and flashing lights when they’re trying to sleep so they made hinged wooden clappers to scare the crows.

Clappers used to disperse crows (photo courtesy Alex Toner, Univ of Pittsburgh)

The clappers worked for a while … but crows are persistent so this week Pitt had to add flashing lights.

This tug of war with winter crows happens every year when thousands come to Pittsburgh to spend the winter. By mid-November the crows wear out their welcome in Oakland and are “encouraged” to move to other locations.

Right now there are 6,000 to 10,000 crows trying to sleep at Pitt and until they stop roosting there, I live in their flyway. This video from early Nov 2020 shows what it was like outside my apartment on 5 November.

Pittsburgh’s winter crow flock flying to the roost, 2 & 4 Nov 2020 (video by Kate St. John)

By the end of the year the crow flock will number 20,000 and the roost will have moved at least once or twice. Where will they be on 30 December when I have to count crows for the Pittsburgh Christmas Bird Count? I’ll need to find out.

(credits are in the captions)

Pignuts

Nuts, Trees
Pignut with husk partly gone, Oct 2023 (photo by Kate St. John)

15 November 2023

The Nutty Series: Pignut hickory

Different species of hickory nuts look the same … but not quite. This one, partially in its husk, was a puzzle so I brought it home. Husks and shells together provide the clues so I had three nuts to work with in various stages of undress, plus a table of southwestern PA hickory husk and shell characteristics.

Pignuts in husk, shell with insect hole, partially in husk, Nov 2023 (photo by Kate St. John)
Characteristics of Southwestern PA Hickory Husks and Shells
Common NameScientific name
Husk
Shell
Shagbark HickoryCarya ovataNearly round, 1.75", thick, green, splits to baseNut has 4 ribs
Mockernut hickoryCarya tomentosaOval to pear shaped, 1.75", green, husk is thinner than shagbark's, splits to baseNut is thick-shelled with 4 ribs
Pignut hickoryCarya glabraOval or slightly pear shaped, 1.5", thin husk green to tan, maturing to da
rk brown, usually splits only partway to base		Nut has no ribs
Bitternut hickoryCarya cordiformisVery thin rough husk with 4 wings, splits only to the middle as if it is peeling off the shellNut is round, small and thin-shelled with a pointed tip

The Verdict: The photo was taken after the nuts sat indoors for three weeks. The husk is still pear shaped but has turned brown and splits completely. Hmmm. The nut, however, has no ribs so I’d say this is a pignut.

Sliced open it would look like this. I lack the tools to make such a clean cut.

Pignut sliced open (photo by Rebekah D. Wallace, University of Georgia, Bugwood.org)

Pignuts were too bitter for European settlers so they fed them to their pigs, hence the pignut name. However pignuts are prized by wildlife including chipmunks, squirrels, mice, blue jays, red-bellied woodpeckers and wild turkeys. If deer eat them they will soon disappear from the ground in Pittsburgh’s parks.

Pignut hickories (Carya glabra) range along the east coast (the original colonies) all the way to the Mississippi Valley and down to the Gulf of Mexico but don’t normally grow in northern Pennsylvania.

Pignut hickory range (map from Wikimedia Commons)

In winter they are best identified by their buds. As with all hickories, the end bud is larger than the side buds but on the pignut it is relatively small and the side buds are almost at right angles to the twig. This one is about to burst into spring leaves.

Pignut hickory buds (photo by Chris Evans, University of Illinois, Bugwood.org)

Young trees have smooth bark. Mature ones have these ridges.

Mature bark on a pignut hickory (photo by Rebekah D. Wallace, University of Georgia, Bugwood.org)

The tree’s compound leaves have 5-7 serrated leaflets …

Pignut on the hickory tree (photo by Franklin Bonner, USFS (ret.), Bugwood.org)

… which turn a beautiful golden color in the fall.

Pignut hickory in autumn (photo by T. Davis Snydor, The Ohio State University,Bugwood.org)

But now the trees are bare.

Bare pignut hickory (photo by T. Davis Sydnor, The Ohio State University, Bugwood.org)

Bonus! Did you notice the clean hole in the center nut in my three-nut photo? It was probably made by a pecan weevil (Curculio caryae). The weevil drills a hole to lay its eggs inside developing hickory nuts, including pecans.

Pecan weevil drilling into a husk (photo by Jerry A Payne, USDA Agricultural Research, Bugwood.org)

How does she drill into the nuts? Check out this video of acorn weevils drilling and mating.

Read more about pignuts at the Glen Arboretum.

(credits are in the captions)

Tiny Blue Lights In The Woods

Insects, Musings & News

14 November 2023

On my way to somewhere else I found … tiny blue lights in the woods. I have never seen them in person but these photos from Anna Ruby Falls Recreation Area in the Chattahoochee National Forest are intriguing. Bioluminescent mushrooms glow green, fireflies glow yellow-green, but these are blue.

Each light is one of two ends of a fungal gnat larvae (Orfelia fultoni). This photo by Alan Cressler, embedded from Flickr, shows what the larva looks like during the day.

Orfelia fultoni, Anna Ruby Falls Recreation Area, Chattahoochee National Forest, White County, Georgia 5
Orfelia fultoni, Anna Ruby Falls Recreation Area, Chattahoochee National Forest, White County, Georgia 5 (photo embedded from Alan Cressler on Flickr)

Alan Cressler describes them:

Orfelia fultoni, Anna Ruby Falls Recreation Area, Chattahoochee National Forest, White County, Georgia:

This is the only bioluminescent fungus gnat larvae in North America. Both whitish ends of the larvae emit a blue light used to lure prey. Although they may be common in proper habits, apparently there are very few places in the southeast where they form extensive colonies. One place is Dismal Canyon in Alabama where they are locally called “dismalites”. I was invited by my friends who work for the Chattahoochee National Forest to view and photograph the extensive colony at Anna Ruby Falls Recreation Area. Locally the event is called “fox fire” and there are scheduled night hikes to witness the amazing colony. Other than the guided night hikes, after hours entry into the area is prohibited.

Fungus gnat larvae live within a slime tube and develop a network of sticky filaments that capture prey that are attracted by the blue glow. The sticky filaments can be seen in the photos.

— Orfelia fultoni, Anna Ruby Falls Recreation Area description, Alan Cresler on Flickr

In the photographs above, the lights don’t look connected but you can see how they move in this video in New Zealand. The bluish glow worms in New Zealand are not the same species but they have a similar appearance and behavior.

video embedded from PBS Deep Look

Back in Georgia the foxfire glows mid-May through June when the gnat’s larval form is alive. Night hikes are offered during those months but pre-registration is required and the hikes fill up fast. Don’t wait until May 2024 to check this website for Foxfire Night Hikes at Anna Ruby Falls: https://gofindoutdoors.org/events/foxfire-night-hikes-coming-soon/

(Originals and credits of the slideshow photos can be seen by clicking on each photo)

Yesterday at Duck Hollow: A Few Good Birds

Phenology
Monongahela River valley at Duck Hollow, 12 Nov 2023, 10:30am (photo by Kate St. John)

13 November 2023

Warbler migration is over and waterfowl migration has not yet reached Pittsburgh so at times we seem to be in a birdless state. The Monongahela River at Duck Hollow was in that condition at yesterday’s Duck Hollow outing — a dozen mallards and 1(!) Canada goose — but we found a few good birds in the thickets.

When we arrived the sky was brilliantly blue with some russet trees on the hillsides. Our group of five was so small that we didn’t do go-around-the-circle introductions and I forgot to take a group photo.

Brilliant blue sky, fading leaves, Duck Hollow, 12 Nov 2032 (photo by Kate St. John)

One golden-crowned and three ruby-crowned kinglets bopped around us as we looked up this hill.

Best birds of the day were five purple finches (Haemorhous purpureus) — one male and four females — that were too far for a photograph, so here’s one from Wikimedia. We parsed out the females first: Very brown stripes on chest, wide white eyebrow, brown face, brown head, notched tail.

Female purple finch (photo from Wikimedia Commons)

Then we saw the lone male (again this photo is from Wikimedia). House finches were nearby for comparison. Here’s how to tell the difference –> Purple and House.

Male purple finch (photo from Wikimedia Commons)

Later a northern mockingbird came close for a photo, this one by Charity Kheshgi.

Northern mockingbird, Duck Hollow, 12 Nov 2023 (photo by Charity Kheshgi)

View our checklist online at https://ebird.org/checklist/S154301974 and below.

Duck Hollow, Allegheny County, Pennsylvania
Nov 12, 2023 8:30 AM – 10:15 AM
5 participants, 25 species

Canada Goose (Branta canadensis) 1
Mallard (Anas platyrhynchos) 12
Mourning Dove (Zenaida macroura) 3
Killdeer (Charadrius vociferus) 3
Herring Gull (Larus argentatus) 2
Red-shouldered Hawk (Buteo lineatus) 1
Red-tailed Hawk (Buteo jamaicensis) 1
Belted Kingfisher (Megaceryle alcyon) 1
Red-bellied Woodpecker (Melanerpes carolinus) 1
Downy Woodpecker (Dryobates pubescens) 1
Northern Flicker (Colaptes auratus) 1
Blue Jay (Cyanocitta cristata) 5
Carolina Chickadee (Poecile carolinensis) 3
Ruby-crowned Kinglet (Corthylio calendula) 3
Golden-crowned Kinglet (Regulus satrapa) 1
Carolina Wren (Thryothorus ludovicianus) 4
European Starling (Sturnus vulgaris) 1
Northern Mockingbird (Mimus polyglottos) 3
American Robin (Turdus migratorius) 8
House Finch (Haemorhous mexicanus) 8
Purple Finch (Haemorhous purpureus) 5
American Goldfinch (Spinus tristis) 5
White-throated Sparrow (Zonotrichia albicollis) 8
Song Sparrow (Melospiza melodia) 3
Northern Cardinal (Cardinalis cardinalis) 6

(credits are in the captions)

A Wasp, An Oak, and Indelible Ink

Insects, Musings & News, Trees
Screenshot from Making Manuscripts: Oak Gall Ink (source video below from the British Library on YouTube)

12 November 2023

Nowadays it’s rare to write anything by hand unless it’s the size of a Post-It note. When we really want to say something we use keyboards and touch screens to generate digital text read on screens or, less often, on paper. Our writing equipment becomes obsolete so rapidly that our computers and cellphones are replaced within a decade. (Who among us is still using the same cellphone since 2013? Do we even remember what model it was?)

So consider this: Humans used the same writing tool, the same indelible ink, from the 5th to the 19th century. When applied to parchment, it is readable 1,700 years later. The ink is easy to make by hand from natural ingredients and is still used in calligraphy today. To make iron gall ink, the process starts with a wasp and an oak.

When a cynipid wasp lays an egg in a developing oak leaf bud, the hatched larva secretes a substance that makes the oak surround it with a gall. The wasp (Andricus kollari) and the oak marble gall below are from Europe but similar wasps and oak galls occur in North America(*).

Cynapid wasps, Andricus kollari, whose larvae are found in oak marble galls (photo from Wikimedia Commons)

The outer shell of the gall is rich in tannins whose presence protects the wasp from predation.

Oak marble gall on white oak forced by Andricus kollari (photo from Wikimedia Commons)

When crushed and soaked in water the galls’ tannins give color to the ink.

Oak marble galls on the twig, forced by Andricus kollari (photo from Wikimedia Commons)

Two more ingredients transform the ink for final use: Iron sulfate dissolved in water makes the ink black.

Iron sulfate crystals (photo from Wikimedia Commons)

Gum arabic dissolved in water makes the ink sticky enough to hold onto parchment or paper.

Gum arabic in lumps and powder (photo from Wikimedia Commons)

This video from the British Library shows how iron gall ink is made.

(video embedded from the British Library on YouTube)

Eventually we used paper instead of parchment, even for important documents, and iron gall ink fell out of favor because the acid in iron sulfate makes the paper disintegrate. To solve that problem we invented paper-friendly inks and then computers.

Iron gall ink has oxidized the cellulose, causing the paper to disintegrate (from Wikimedia Commons)

Medieval manuscript creation used natural products from animals, plants and minerals. See the process from parchment to ink to binding in this 6-minute video from the Getty Museum.

video embedded from the Getty Museum on YouTube

Read more at Making Ink From Oak Galls: Some History & Science.

(*) p.s. The amount of tannin varies by type of gall and the tree species the gall came from. Galls with the most tannin work best.

(credits are in the captions)

Seen This Week: Owl, Crows and Deer

Birds of Prey, Crows & Ravens, Phenology, Trees
Eastern screech-owl, Frick Park, 7 Nov 2023 (photo by Charity Kheshgi)

11 November 2023

Songbird migration is quiet now and birds, when they’re found, are in mixed species flocks.

On 7 November, Charity Kheshgi and I encountered agitated golden-crowned kinglets, tufted titmice and dark-eyed juncos but it took us a while to find what they were upset about. This red morph screech-owl was hiding above our heads in a small oak.

Golden-crowned kinglet, Frick Park, 7 Nov 2023 (photo by Charity Kheshgi)

An exception to the mixed species flocking rule is our “murder” of crows. My guess is that Pittsburgh’s winter crow flock is 90% American and 10% fish crows, but who can tell? They look alike.

In late afternoon crows stage in the trees in Shadyside and Squirrel Hill, then head west at sunset. 6,000 to 10,000 pass by my building on their way to the roost.

Crows staging in Squirrel Hill just before dusk, 10 Nov 2023 (photo by Stephen Tirone)

At sunset black birds in a darkened sky are impossible to photograph but it’s another story at sunrise. Click on the photo below for a closeup of crows in the brightening sky.

Sunrise with crows, 2 Nov 2023 (photo by Kate St. John)

Leaves littered the ground this week and the air was filled with the sound of leaf blowers. 🙁

Fallen red maple leaf, 7 Nov 2023 (photo by Kate St. John)

Most of the trees were bare in Schenley Park by Friday 10 November.

Bare tree touched by sun, Schenley Park, 3 Nov 2023 (photo by Kate St. John)
Most of the trees are bare, 10 Nov 2023 (photo by Kate St. John)

And finally, a reminder that the rut is still in progress and deer are crossing roads. This duo showed up at a Squirrel Hill polling place on Election Day at a place surrounded by roads. So watch out.

Deer at the polling place on Election Day, 7 Nov 2023 (photo by John via Mardi Isler)

(credits are in the captions)