Yearly Archives: 2025

Last Night at the Pitt Peregrine Nest

Bird Behavior, Nesting & Courtship, Peregrines
Carla at the nest at night, 15 March 2025 11:28pm (photo from the National Aviary falconcam at Univ of Pittsburgh)

16 March 2025

When a female peregrine is getting ready to lay eggs she spends the night at the nest ledge. As egg laying becomes imminent she doesn’t have far to go to crouch over the scrape.

Last night Carla spent five hours at the nest and, from the start Ecco encouraged her to do so.

This Day-in-a-Minute timelapse video shows nest activity from 10:30 on Saturday night through 7:00am Sunday morning, 15-16 March, as follows:

  • 15 March 2025: The nest is empty from sunset until 10:30pm, not shown in the video.
  • When Ecco arrives he pops in and out so fast that you might not realize it’s him. Carla arrives soon after.
  • Carla stands on the gravel or the green perch for most of the night; she leaves at 4:40am.
  • A few minutes later Ecco arrives, checks the scrape and spends a while on the green perch.
  • Ecco leaves near dawn.
(Timelapse video from the National Aviary falconcam at Univ of Pittsburgh)

The real time video clip below shows the most interesting segments. With audio on you can hear Carla calling before she leaves the nest, perhaps wailing to Ecco for a snack. After a short gap with no peregrines, Ecco comes to the nest.

(Real time video clip from the National Aviary falconcam at Univ of Pittsburgh)

Fingers crossed we’ll see the first egg this week. Watch for it at the National Aviary falconcam at the University of Pittsburgh’s Cathedral of Learning.

p.s. Nighttime activity is not unusual among peregrines. Fifteen years ago Louie was famous for it at the Gulf Tower. See Remembering Louie: 2002-2019

Seen This Week: Owlet, Planets, and Incipient Spring

Birds of Prey, Phenology, Weather & Sky
Great horned owlet in a tree in Schenley Park on 14 March 2025 (photo by Dana Nesiti)

15 March 2025

The great horned owlet that fell from its nest in Schenley Park and was returned on 11 March was relatively easy to find on Wednesday, posed like a statue on a sloping tree branch (below).

Great horned owlet on a branch, Schenley Park, 12 March 2025 (digiscoped by Kate St. John)

The owlet spent Thursday well camouflaged on an inaccessible-to-humans cliff ledge. On Friday she was in a tree, see photograph at top. Juvenile owls use their claws to climb trees. (Note: in case you hear people calling her Muppet, Tamarack gave her that nickname.)

Mercury and Venus

After sunset on 9 March I noticed a bright planet in the west with a divot out of the top of it like a phase of the moon. It was Venus about to set. How did I live this long without knowing that Venus has phases?

Phases of Venus (diagram from Wikimedia Commons)

When I digiscoped Venus I saw a shadowy planet next to it. Mercury was also about to set, pinkish and to the left of Venus whose brightness plays havoc with my optics.

Mercury and Venus with a divot off the top, 9 March 2025 (digiscoped by Kate St. John)

Here’s a view that shows Venus a bit better.

Mercury and Venus, 9 March 2025 (digiscoped by Kate St. John)
Incipient Spring flowers and leaves

Incipient is a good word to describe spring flower and leaf status this week. As of Thursday 13 March spring was “in an initial stage; beginning to happen or develop.”

Common whitlowgrass blooming in Aspinwall, 11 March 2025 (photo by Kate St. John)

Common whitlowgrass (Draba verna), a member of the cabbage family, blooms very early. It is native to Europe, western Asia and North Africa and is now spread around the world.

Honeysuckle leaves were just beginning to open on Thursday.

Incipient honeysuckle leaves in Greenfield, 13 March 2025 (photo by Kate St. John)

And the Cornelian cherry tree near Panther Hollow Lake had a single tiny flower open in the bud.

Incipient Cornelian cherry flowers, Schenley Park, 13 March 2025 (photo by Kate St. John)

All of these plants are from other continents and they start blooming sooner than our native plants.

After yesterday’s very warm weather everything else will speed up.

Cool Corvids: Raven Pairs on Territory

Bird Behavior, Crows & Ravens
Raven pair in flight (photo from Wikimedia Commons)

14 March 2025

I’ve seen a lot of ravens in the past two weeks — 11 in Minnesota, two as we landed at Pittsburgh airport, and one over Aspinwall on Tuesday. When I found Vance Crofoot’s 3-minute video explaining raven territories I was fascinated.

video embedded from Exploring wildlife with Vance Crofoot on YouTube

Here’s what we learned:

  • Immature ravens spend 3 to 4 years in large flocks of young ravens. On reaching adulthood, ravens pick a mate and go off to claim a territory.
  • Adult pairs display their territorial boundary by flying along the border.
  • Ravens know their neighbors and will sometimes fly with them along the mutual border.
  • Ravens help their neighbors drive out predatory threats.
  • Other ravens are not allowed to land in an adult pair’s territory. If they do they are challenged.
  • When a pair has chicks they aggressively drive out predators.
  • Once the chicks can fly, neighboring families meet up for “play dates” with their kids.
  • Youngsters also can bring friends home to play with.
  • Juvenile ravens stay with their parents for about 7 months. At the end of that time their parents aggressively drive them out of the territory.

The first comment on the video points out how different ravens are from crows!

Very informative! It’s interesting that the intergenerational behaviour is different from crows whose juveniles hang around longer and actively assist their parents in raising the next chicks and fledglings. The ravens’ cooperative behaviours are very well adapted to their needs and types of threats.

— Comment on the video from @julieprior3126

And why are there so many ravens in this video? Southern California has a lot more ravens than we do in the East, as shown on this eBird map.

Sightings of common ravens in North American in the past 10 years, 14 March 2025 (map from eBird)

Why Owls Can Turn Their Heads So Far

Bird Anatomy, Birds of Prey
Great horned owl with head facing over its back (photo from Wikimedia Commons)

13 March 2025

Owls have excellent eyesight but they see the world differently than we do.

When we look straight ahead (fixation point below) our peripheral vision allows us to faintly see our hand waving near our ear — a 200-220° field of view.

Human field of view (diagram from Wikimedia Commons)

Owls have binocular vision similar to ours but their peripheral vision is much narrower. They cannot even see 180°.

Field of View diagram for owl derived from an illustration on Wikimedia Commons

To make matters worse they cannot move their eyes!

Great horned owl eye closeup (photo from Wikimedia Commons)

Since their eyes are always facing forward, they have to move their heads or their bodies to see anything outside their narrow field of view. Moving their bodies would alert their prey, so owls have evolved to move their heads as far back as they need to see — up to 270°.

  • Owls have 14 neck bones for greater flexibility. We have only 7 neck bones
  • The owls’ atlanto-occipital neck joint has evolved to move the head further back.

When you can’t move your eyes, you have to move your head.

video embedded from Garry Hayes on YouTube

Fallen Owlet Returned to Schenley Park

Birds of Prey, Nesting & Courtship
Great horned owlet about to be delivered to temporary nest, Schenley Park 11 March 2025 (photo by Dana Nesiti)

12 March 2025

Almost two weeks ago this 6-week-old great horned owlet fell 100 feet from her nest on the Panther Hollow Bridge and was rescued and taken to Tamarack Wildlife Center. Tamarack determined her injuries were so minor that she was ready for release quite soon. But where to take her? Her birth-nest is inaccessible.

Panther Hollow Bridge, Schenley Park, with owls’ nest indicated (photo by Kate St. John)

She needed to be in a foster family with siblings her age but she is older than other known nestlings in western PA. (Her parents nest really early.) In the end the best choice was to return her to her parents by placing her in a temporary nest near the bridge.

Yesterday she went home with help from Tamarack Wildlife Center, City of Pittsburgh Forestry and Pittsburgh Park Rangers. Her adventure is documented in these photos by Dana Nesiti.

First, her temporary nest was placed 20-30 feet up in a tree within sight and sound of her parents. Then George DeSavage of City Forestry received her from Tamarack staff.

The handoff, great horned owlet on his way to the temporary nest in Schenley, 11 March 2025 (photo by Dana Nesiti)

As a parting shot she bite the gloved finger of her Tamarack handler. Fortunately those gloves are very thick.

Owlet bites a finger during the handoff, fortunately in a stout glove! Schenley Park, 11 March 2025 (photo by Dana Nesiti)

Then she rode in the bucket truck to her temporary nest …

Owlet on his way to the temporary nest via bucket truck, Schenley Park, 11 March 2025 (photo by Dana Nesiti)

… and settled in.

Great horned owlet in his temporary nest, Schenley Park, 11 March 2025 (photo by Dana Nesiti)

She is just the right age to begin “branching” — walking off the nest — so her parents will not be surprised to hear her away from the birth-nest. When she wakes up hungry she will make begging calls like this and her parents will bring her food.

Tamarack explains:

Over the next 3-4 weeks, she will practice perching, hopping, flapping and short flights before being fully able to fly at around age 9 weeks.

Great Horned Owls spend more time with their young than any other owl species in Pennsylvania. Six months or more are spent supporting their young and teaching them hunting skills, before encouraging their young to disperse in the fall.

— Tamarack Wildlife Center Facebook pAGE

Read more about her adventure in the Post-Gazette Great horned owl named Muppet, rehabbed after 100-foot fall, returned to Schenley Park.

Follow Tamarack Wildlife Center on Facebook where they mention how to help them rehab wildlife.

If you would like to contribute and to be part of making this and other treatments and reunions possible, check out www.tamarackwildlife.org

— Tamarack Wildlife Center Facebook pAGE

U.S. Butterflies Declined 22% in Only 20 Years

Insects, Musings & News
West Virginia white (Pieris virginiensis) in 2008 (photo from Wikimedia Commons)

11 March 2025

A new study published last week in the journal Science analyzed butterfly surveys from 2000 to 2020 to determine the population status of each species in the continental U.S. The results were sobering.

Total butterfly abundance (all individuals of all species) decreased across the contiguous US at a rate of 1.3% annually, for a cumulative 22% decline in overall abundance between 2000 and 2020.

— Science: Rapid butterfly declines across the United States
during the 21st century

The only region of the continental US that didn’t suffer was the Pacific Northwest where the total population remained stable and the highly irruptive California tortoiseshell (Nymphalis californica) surged on and off as expected.

The study found that declines were common and increases rare.

Over our two-decade study period, 33% of individual butterfly species (114 of 342) showed significantly declining trends in abundance. Conversely, only 3% of species increased.

— Science: Rapid butterfly declines across the United States
during the 21st century

For instance, the West Virginia white (Pieris virginiensis), above, declined each year by nearly 20%, in part because they are fooled into laying eggs on invasive garlic mustard that kills their caterpillars. By now 98% of them are gone.

And in southern Texas and south Florida the Soldier butterfly (Danaus erisemus), a relative of the monarch, declined about 15% per year, which means about 96% of them gone.

Solider or Tropical Queen butterfly (Danaus erisemus), Loxahatchee, Florida, 2016 (photo from Wikimedia Common)

Learn more about the study and see the graphs of declining species in Science.

Meanwhile, what can we do to save butterflies? In some cases it simply means planting the butterfly’s host plant. The zebra swallowtail returned to Pittsburgh after an absence of 87 years(!) because many people planted its host plant, the pawpaw tree.

Pitt Peregrine Courtship Beak to Beak

Nesting & Courtship, Peregrines
Ecco and Carla touch beaks during courtship on 9 March 2025 (photo from the National Aviary falconcam at Univ. of Pittsburgh)

10 March 2025

Did you know that peregrines touch beaks during courtship?

As egg laying time approaches, Pitt peregrines Ecco and Carla have been courting four and five times a day and engaging in long bowing sessions. Yesterday’s courtship included several touching moments beak-to-beak (shown below without distracting audio).

video excerpt without audio, 9 March 2025 12:14pm, from the National Aviary falconcam at Univ of Pittsburgh)

After Ecco left, Carla stayed at the nest for more than an hour stretching, snoozing, sunning, puttering , and preening. This is a good sign that she’s getting into breeding condition.

Carla putters at the nest, 9 March 2025
(snapshots from the National Aviary falconcam at Univ. of Pittsburgh)

We will know egg laying will happen soon when Carla spends the night at the nest.

Watch her at the National Aviary falconcam at the University of Pittsburgh’s Cathedral of Learning.

Population Hit by Bird Flu Recovered in Just 2 Years

Migration, Musings & News, Water and Shore
Barnacle goose closeup (photo from Wikimedia Commons)

9 March 2025

Every autumn barnacle geese (Branta leucopsis) leave their arctic breeding grounds and migrate to Europe. In 2021-2022, those wintering at Solway Firth, UK(*) became infected with highly pathogenic avian influenza (HPAI) H5N1 and 31% of them died. Even though their population had been devastated, they recovered to full strength in just two years. This can give us hope for North American birds hit hard by bird flu.

Wild barnacle geese breed in Greenland, Svalbard and Siberia yet each population has its favorite wintering site as shown on the map. Counts on the wintering grounds are directly tied to one breeding location.

Distribution of barnacle geese highlighting the studied population in 2021-22 (map from Wikimedia Commons)

The winter population at Solway Firth breeds at Svalbard.

Wintering flock of barnacle geese in the fog at Solway Firth (photo from Wikimedia Commons)

When bird flu hit Solway Firth in the winter of 2021-2022 researchers began a two+ year study to measure the demographic impact of the major HPAI outbreak on barnacle geese. During the outbreak they carefully counted dead goose carcasses and, thanks to fencing, were able to extrapolate for predation.

By February 2022 the barnacle goose population had dipped precipitously, but in the two years that followed the number of juveniles increased even faster. High birth rates on the breeding grounds quickly made up for the loss of adults.

Year to year maximum late-winter count of barnacle geese at Solway Firth. From Impacts of highly pathogenic avian influenza (HPAI) on a Barnacle Goose Branta leucopsis population wintering on the Solway Firth, UK

Researchers speculated that …

The large impact of HPAI-related mortality on the Solway Barnacle Goose population was rapidly recovered, probably through a combination of the widespread development of natural immunity and high levels of breeding success in the years following the outbreak.

— Impacts of highly pathogenic avian influenza (HPAI) on a Barnacle Goose Branta leucopsis population wintering on the Solway Firth, UK

In Pennsylvania, snow geese have been hard hit with wild bird flu. It will be interesting to watch how their winter population fluctuates in the eastern U.S. in the years ahead.

p.s. We don’t have barnacle geese in the U.S. Here’s look like.

Barnacle geese (center of photo) look unique but are similar in size to their nearest relative the cackling goose.

One barnacle goose with many cackling geese (photo from Wikimedia Commons)

Size comparison! Though cackling geese look like Canada geese they are much smaller. Thus barnacle geese are smaller than Canada geese we see in Pittsburgh.

Two cackling geese with a Canada goose (photo from Wikimedia Commons)

(*) Solway Firth forms the western border of Scotland and England.

Seen This Week: Winter Weeds and Trees

Trees, Winter Weeds & Trees
Golderod in winter, Beechwood Farms, 3 March 2025 (photo by Kate St. John)

8 March 2025

During this week’s brief and gorgeous warm weather I thought it was spring and took photos of interesting plants at Beechwood Farms. Back home I see that they are wintry weeds and trees with only a hint of what is to come.

Goldenrod, above, has not yet released its fluffy seeds to the wind.

I was fascinated by the yellow bark on these maple-family twigs. Is it box elder …?

Whose bud is this? Beechwood farms on 3 March 2025 (photo by Kate St. John)

Yes. The yellow bark threw me off but the opposite buds and green bark on older branches are both traits of box elder (Acer negundo).

What species is this small tree? Beechwood Farms on 3 March 2025 (photo by Kate St. John)

The mystery leaves, below, required my plant identification tool but the answer was unsatisfying and probably wrong. Dame’s rocket (Hesperis matronalis)? I doubt Beechwood would have left such an invasive plant in place.

New leaves at Beechwood Farms on 3 March 2025 (photo by Kate St. John)

However, the tool pointed me to a video about eating Dame’s rocket (Hesperis matronalis) in the spring. Great idea! This plant is invasive. (In the video it is called wild phlox. Maybe a Canadian common name for it.)

video embedded from EdibleWildFoods on YouTube

Speaking of edible plants, several parts of burdock are edible and the roots can be eaten year round.

Burdock in winter, Beechwood Farms, 3 March 2025 (photo by Kate St. John)

Dig it up and eat it. This plant is invasive. Read more before you dig –> Northern Woodlands Burdock: A Food That Will Really Grab You.

Look Who Has Wings!

Birds of Prey, Nesting & Courtship
Great horned owl nestling showing new wings, 4 Mar 2025 (photo by Jim McCollum)

7 March 2025

On Tuesday 4 March Jim McCollum visited Schenley Park to see the great horned owls’ nest. While there he was lucky to see a nestling stand up and stretch. Look who has wings!

Great horned owls in Schenley Park, 4 March 2025 (photos by Jim McCollum)

These wings are not fully developed yet but they are looking good and will be further along today than they were three days ago.

When will the Schenley owlets fly?

Here is my best guess at when the nestlings will fly from the Schenley Park bridge nest.

  • Based on their appearance and behavior I think the first egg hatched around 5 February and the second about two days later. Approximate hatch dates = 5-7 Feb. [Update from Tamarack: Hatching was approx 28-30 January.]
  • Great horned owl nestlings walk off the nest and start “branching” at 5-6 weeks = approximately 12-21 March.
  • Branching youngsters fly away from the nest — “fledging” — at 9-10 weeks = early April. I am not sure of this estimate. It may be sooner (late March) though I doubt it will be later in April.


Recap: Where to View the Nest
If you want to see the owls’ nest bring binoculars, a camera and a scope if you have them to this location in Schenley Park near the stone bench on the Lower Trail (click this link for the map).

Here’s what the bridge looks like when you get there. Look for the nest at the red circle area in this photo.

Panther Hollow Bridge, Schenley Park, with owls’ nest indicated (photo by Kate St. John)