A Swift Game of Skittles

Bird Behavior, Peregrines
Peregrine approaches, dangling a menacing foot, 2021 (photo by Chad+Chris Saladin)

19 September 2021

The rooftop deck of my building overlooks the largest chimney swift roost in the Pittsburgh area, the Cathedral Mansions chimney, so I wasn’t surprised when Sarah Koenig of Audubon Society of Western PA emailed to arrange a location for a live online Chimney Swift Watch.

Sun pillar next to tall chimney (swift roost) at Cathedral Mansions, 19 Sept 2021 (photo by Kate St. John)

Unfortunately it didn’t look good for a live event. Since Hurricane Ida I hadn’t seen many swifts but I decided to take a look. On Thursday evening, 16 September, I went to the roof at sunset to count the swifts.

Chimney swifts near a peregrine nest site in Ohio, 2021 (photo by Chad+Chris Saladin)

By 7:40pm about 100 swifts were circling the chimney and one had just dropped in. Suddenly I was distracted by a large bug that banged right into me. I brushed it away and I looked at the chimney again and there were no swifts at all! I’d been distracted for mere seconds and I know it takes many minutes for the flock to drop in. Where did they go? As I waited and watched the swift inside the chimney came out and flew away, too. Huh?

I tried again last night, Saturday 18 September. This time I looked for all species. I saw 400+ crows heading for Oakland after sunset and a peregrine perched on the Cathedral of Learning.

As the sky darkened I focused exclusively on the chimney. Again, 100+ swifts circled the chimney and I waited to count them as they dropped in. It was 7:40pm.

Cathedral Mansions chimney with swifts circling, September 2020 (photo by Michelle Kienholz)

And then they were gone.

But this time I knew why. As I watched a peregrine approached the chimney from the darkened eastern sky. He could see the flock silhouetted against the sky but the swifts couldn’t see him until he flew through the flock and scattered them like small bowling pins.

Peregrine approaches a flock, 2017 (photo by Chad+Chris Saladin)

For the peregrine is was a game of skittles. For the swifts it was life or death. Peregrines can grab swifts in the air. Maybe he did.

Peregrine with chimney swift prey at St. Ignatius, 2020 (photo by Chad+Chris Saladin)

This swift game of skittles is new behavior for the Pitt peregrines but it may be that Ecco is trying out new things during his first autumn at Pitt.

I hope he gets over these sunset games. I’d like to see a lot more swifts at the chimney.

(photos by Chad+Chris Saladin, Kate St. John, Michelle Kienholz)

Caterpillar Attracts Attention, Moth Does Not

Insects, Fish, Frogs
American dagger moth caterpillar, 13 Sep 2021 (photo by Kate St. John)

18 September 2021

This gorgeous yellow caterpillar is an American dagger moth (Acronicta americana), a 2-inch long member of the owlet family Noctuidae. As a caterpillar he attracts attention.

As a moth he does not.

Adult American dagger moth (photo from Wikimedia Commons)

The difference is a matter of self defense. The adult American dagger moth is probably good to eat so he does his best to hide.

The caterpillar is conspicuous because he has a toxin in his black bristles that cause a stinging sensation when the bristles break off and embed in skin. Like many poisonous animals he’s using aposematic coloration and behavior to simultaneously attract attention and warn off predators, “Look. Don’t eat me.” Other examples include poison frogs, monarch butterflies and skunks.

However, this caterpillar is not invincible like the hickory tussock moth. If you know what you’re doing it’s possible to flatten the black bristles and touch the dagger moth caterpillar as Rebekah D. Wallace does, below, to show the spiracles under the caterpillar’s “fur.”

An expert carefully flattens the bristles to show the lateral spiracles (photo by Rebekah D. Wallace, University of Georgia)

No thanks. I’ll look but not touch.

(photos by Kate St. John, Wikimedia Commons, and Rebekah D. Wallace, University of Georgia via bugwood.org; click on the captions to see the originals)

Are the Swifts Gone?

Migration
Chimney swift flying in Austin, Texas (photo by Jim McCullough, Creative Commons license, Wikimedia Commons)
Chimney swift, Austin, Texas (photo by Jim McCullough, Creative Commons license, Wikimedia Commons)

16 September 2021

Because chimney swifts (Chaetura pelagica) eat insects on the wing, they eat while they migrate during the day then roost in chimneys at night. In August they begin leaving Pittsburgh and are gone by early October on their way to South America. Mid-September is usually prime time for watching them swirl and drop into chimneys at dusk.

Last year I was thrilled to watch 1,500 of them diving into the roost at the Cathedral Mansions chimney.

Chimney swifts swirl around the Cathedral Mansions chimney at dusk, Sep 2020 (photo by Michelle Kienholz)

But not this year.

Ever since Hurricane Ida passed through Pittsburgh, chimney swifts have been relatively rare and nearly absent from Cathedral Mansions. Earlier this week Steve Tirone, who watches swifts in Squirrel Hill, commented on the low numbers in his area. We’ve seen flocks of about 20 during the day but not the great numbers we usually expect.

Are the swifts gone? Have you seen large flocks of chimney swifts lately? Where?

(photos from Wikimedia Commons and Michelle Kienholz)

Not Truly Blue

Musings & News
Purple honeycreeper, Trinidad (photo by Greg Smith via Flickr, Creative Commons license)
Purple honeycreeper, Trinidad (photo by Greg Smith via Flickr, Creative Commons license)

15 September 2021

If you take photos of purple things you may have noticed that your camera renders the images as blue.

My classic example is the purple honeycreeper photo which I used on the blog in 2014. The bird looks blue in the photo above but in the photo below, taken with a different camera or edited differently, the bird is purple. The field guide says he is deep violet-blue, thus named the purple honeycreeper.

Purple honeycreeper as he looks in real life (photo from Wikimedia Commons)

The purple-turns-blue problem is caused by the fundamental difference between how our eyes see violet light and how a camera does.

Our eyes have color receptors that pull in three colors of light — short wavelength (S) blue, middle wavelength (M) green, and long wavelength (L) red — with sensitivity peaking at certain wavelengths. Our brains process color by noting the ratios from each receptor. When we see purple our brains detect information from the blue and red sensors.

Camera color receptors pull in the same colors too but they peak at slightly different wavelengths than our eyes and the camera processes blended colors differently than our brains do. Robert Schleif at Johns Hopkins University explains:

Digital cameras distinguish colors in about the same way as the human eye. Most likely however, distinguishing colors at the blue [violet] end of the spectrum utilizes the blue and green sensors rather than the blue and red sensors used in humans.

— Sensing Violet: The Human Eye and Digital Cameras Robert Schleif, Johns Hopkins University

His diagram, link-embedded below, shows the difference between human and Nikon D70 camera color sensitivity.

image embedded from Sensing Violet: The Human Eye and Digital Cameras, Johns Hopkins Dept of Biology, Robert Schleif

Humans register purple in our brains by seeing blue+red. Most cameras register purple using blue+green so they cannot match the color we see.

For example, here’s an unedited photo of a purple aster taken by my Pixel 5 cellphone camera. The camera makes it blue.

The Pixel photo editor can fix it. I used the “Enhance” filter to come closest to the original flower color but this makes the photo too bright to my liking.

Adjusted by Pixel cellphone “Enhance” edit (photo by Kate St. John)

My laptop photo editor can fix it, too, by simply pumping up the red. It’s close to the right color but still not perfect.

Aster photo, adjusted by hand to pump up the red (photo by Kate St. John)

So now you know why deep violet looks blue in many photos. Purple honeycreepers and purple asters are not truly blue.

For more information see Robert Schleif’s article: Sensing Violet: The Human Eye and Digital Cameras.

p.s. Light is violet. Purple is a color constructed by our brains. Bird brains see the color purple differently than we do because they can see ultraviolet light. I’m sure the purple honeycreeper looks quite different to his fellow birds. Perhaps he is ultraviolet.

(photos from Wikimedia Commons and Kate St. John, graph is link-embedded from Sensing Violet: The Human Eye and Digital Cameras, Robert Schleif, Johns Hopkins University Department of Biology)

Check The Antennae

Insects, Fish, Frogs
End band net-wing beetle, Frick Park, 6 Sep 2021 (photo by Kate St. John)

14 September 2021

This bug attracted my attention as it fluttered by so slowly that I thought it was a moth.

When it landed I could see its body shape and antennae were wrong for a moth. Moths usually have feathery antennae like this …

Antennae of an Agreeable Tiger Moth (photo by Chuck Tague)
Antennae of an Agreeable Tiger Moth (photo by Chuck Tague)

… whereas this bug has segmented antennae, as seen in this photo from Wikimedia Commons.

iNaturalist told me it was an “end band net-wing beetle (Calopteron terminale).” The black tip on the elytra (wing coverings) is the “end band.” The large and membranous “net-wings” are covered when the beetle is at rest. Click here to see him with open wings.

In flight I thought he was a moth because “This beetle is a strong, but slow, lumbering flier,” according to North American Insects and Spiders.

Check the antennae to narrow the possibilities. On beetles they can be whimsical.

Longhorn Beetle “Whitespotted Sawyer,” Sequoia National Park (photo from Wikimedia Commons)
Click beetle with antler-like antennae, Tsu, Japan (photo from Wikimedia Commons)

(photos from Kate St. John, Chuck Tague and Wikimedia Commons)

Smart Weeds

Phenology, Plants & Fungi
Oriental lady’s thumb is an Asiatic smartweed, Schenley Park, 10 Sep 2021 (photo by Kate St. John)

13 September 2021

Today’s article began with a question asked three times: What is that weed? I couldn’t remember the name even though I knew each was in the knotweed family (Polygonaceae) and that a similar native species was named for Pennsylvania.

On the first question I took a picture in Schenley Park, above. On the second question, Claire Bauerle took a picture at Duff Park, below. My plant and Claire’s plant are both alien but not the same species.

Lady’s thumb (photo by Claire Bauerle)

Claire’s plant shows its name on its leaves, a shadowy thumbprint in the center of the leaf.

Lady’s thumb (Persicaria maculosa) is a Eurasian smartweed that first appeared in the Great Lakes region in 1843, has spread across the continent, and is sometimes invasive. The dark thumbprint is a simple way to identify the plant.

My plant is similar but lacks the thumbprint. Not the same species but my photo is not detailed enough for a complete identification. My guess is Oriental lady’s thumb (Persicaria longiseta) a common weed in Asian rice paddies introduced to North America near Philadelphia in 1910 and now found across eastern North America.

The third question was answered on Sunday’s Botanical Society walk on the South Side where we found the smartweed named for Pennsylvania.

Pinkweed or Pennsylvania smartweed (Persicaria pensylvanica) now grows in waste places around the world. Gangly-looking compared to the lady’s thumbs, it has longer stalks, thinner leaves, and fatter, shorter, paler flower heads.

Pinkweed or Pennsylvania smartweed mixed in with other weeds, 12 Sep 2021 (photo by Kate St. John)

Here’s a single stalk.

Pinkweed or Pennsylvania smartweed, 12 Sep 2021 (photo by Kate St. John)

It has no flower bristles like those found on Oriental lady’s thumb P. maculata.

Flower heads of pinkweed (photo by Kate St. John)

All three smartweeds have stems that connect to the stalks at knot-like ochreas. Two of them, P. longiseta and P. pensylvanicum have bristly ochreas, shown below.

Bristly ochrea on pinkweed, P. pensylvanicum (photo by Kate St. John)

Identifying smartweeds is much trickier than I’ve described so I may have misidentified the first two plants.

If I was smart I’d know what to look for and take better pictures to key them out.

(photos by Kate St. John and Claire Bauerle)

p.s. Three range maps which might not work in Chrome: P. maculosa, P. longiseta, P. pensylvanica

Bonding and a Lot of Preening

Bird Behavior, Peregrines
Morela and Ecco pair bonding, 10 Sep 2021 (photo from the National Aviary falconcam at Univ of Pittsburgh)

12 September 2021

The Pitt peregrine falcons, Morela and Ecco, are staying close to home and watching fall migration as it passes through Pittsburgh. Every day they visit the nest, bow to strengthen their pair bond, and preen on camera. On 10 September they met twice at the nest, shown below.

A few days ago I wrote about birds that twist their necks. Watch Morela preen the spot between her shoulder blades. I can touch that spot with my fingertips but it’s a stretch!

(photos from the National Aviary snapshot camera at Univ of Pittsburgh)

Fall Is Here

Phenology, Schenley Park, Weather & Sky
Misty walk at Panther Hollow Lake, Schenley Park, 10 Sep 2021 (photo by Kate St. John)

11 September 2021

The weather has been pleasant with low humidity and highs in the 70s. Chilly fall mornings produce a mist on Panther Hollow Lake.

Asters are blooming right on time …

Asters (photo by Kate St. John)

… but this hawthorn tree is confused, opening two flowers and a leaf in September.

Hawthorn tree puts out two flowers and a leaf, Schenley Park, 10 September 2021 (photo by Kate St. John)

This eastern screech-owl confirms it’s fall when he peeks from his well known roost on 4 September. Though screech-owls breed in Schenley Park, they only use this roost during the non-breeding season.

Eastern screech-owl at the winter roost, Schenley Park, 4 Sep 2021 (photo by Kate St. John)

My least favorite hot weather will return tomorrow through Tuesday, forewarned by this morning’s red sunrise.

Red sky at morn, sailors forewarn.

Sunrise in Oakland, Pittsburgh, 11 Sep 2021 (photo by Kate St. John)

(photos by Kate St. John)

Wry and Awry

Bird Anatomy, Bird Behavior
Wrybill, New Zealand (photo from Wikimedia Commons)

10 September 2021

When I think of the word “wry” the first thing that comes to mind is sarcastic or dry mocking humor. “He made a wry comment” and everyone smiled like this:

Wry smiles: cat emoji and Gianni Gambi in 1937 (images from Wikimedia Commons)

At its root “wry” means twisted, bent or turned abnormally to one side. Two birds have “wry” in their names and their bodies show it.

The wrybill (Anarhynchus frontalis) is a plover endemic to New Zealand whose bill is permanently twisted, always to the right.

Wrybill in hand and illustration of bill (images from Wikimedia Commons)

The Eurasian wryneck (Jynx torquilla) is named “twisted neck” but his neck is straight …

Wryneck (photo from Wikimedia Commons)

… until he gets frightened.

All birds can twist their necks to preen, as Ecco demonstrates this week at the Pitt peregrine nestbox.

But the wryneck moves his neck in an mesmerizing way to distract predators.

We stop and stare when his neck is awry.

(images from Wikimedia Commons; click on the captions to see the originals)