UPDATE on 26 March 2023: First egg hatched around noon on 26 March.
It’s been more than a month since the first egg was laid at the Hays bald eagle nest and today, 35 days later, we’re watching for a hatch.
Bald eagle eggs hatch in 34-41 days but thanks to eaglestreamer.org‘s record keeping we know that the Hays eagles hatch at the early end of that spectrum. This year’s predictions are:
Estimated hatch dates (based on 35 days incubation):
It’s that time of year again when Southwestern Pennsylvania’s bald eagles refurbish their nests and start to lay eggs. Two Pittsburgh area nests, Hays and USS Irvin, are in the midst of Egg Watch.
Stop by the Hays Bald Eagle Viewing Area on the Three Rivers Heritage Trail. Click here for directions.
As soon as an egg is laid, visit eaglestreamer.org for the hatch and fledge countdown clock.
USS Irvin Bald Eagles:
This pair has been on site since 2019 and on camera since December 2021. There is no in-person viewing location so check them out on the USS Irvin eaglecam. UPDATES:
Vultures used to abandon the Pittsburgh area in winter but as the climate heated up small groups of turkey vultures (Cathartes aura) began to stay through the coldest months. Then about two years ago black vultures (Coragyps atratus), which are rare here at any time of year, changed their winter habits one bird at a time.
This winter a single black vulture has been roosting with turkey vultures on a cell tower near Audubon of Western PA’s Beechwood Farms Nature Reserve. Every time someone reports him to eBird he pops up in a Rare Bird Alert.
Pennsylvania is the northern fringe of the black vulture’s winter range while the heartland is in Central and South America (see Jan-Feb eBird map below). In Ecuador I saw black vultures every day.
If you want to see huge flocks of black vultures in winter, Florida is the place to be. They perch on buildings or stand around on dikes with their wings open.
Only as big as a European starling, this accipiter native to Central and South America is aptly named the tiny hawk (Microspizias superciliosus).
Why is he so little? Because he eats the smallest birds.
Like all accipiters, the tiny hawk feeds primarily on birds. It hunts hummingbirds and small songbirds, by darting out from a place of concealment to snatch them as they pass by, but also ambushing them when the smaller birds are perched. There is some evidence that it learns the regular perches of some hummingbirds and hunts for them there. Some individuals also hunt rodents and bats.
At first I misread the word as “supercilious” meaning arrogant or haughty. There’s a connection between the two words. Arrogant or haughty people sometimes raise one eyebrow to show their attitude toward others.
We didn’t see the tiny hawk during our Ecuador birding trip because we were in Mindo & the northwest highlands while he lives in the lowlands and foothills.
(photo from Wikimedia Commons; click on the caption to see the original)
Red-tailed hawk casting a pellet, 2018 (photo by Chad+Chris Saladin)
22 January 2023
This red-tailed hawk is not consuming the lump near his mouth. He’s casting a pellet of indigestible bones, fur and feathers that came up from his gizzard. Pellets are a normal by-product of digestion in birds of prey. If you find one, it can tell you what the bird was eating.
We always find pellets during annual maintenance at the Pitt peregrine nestbox including these three found during our 9 January visit (paperclip for scale). The pellets can be many months old.
Peregrine pellets from Cathedral of Learning nestbox, 9 Jan 2023 (photo by Kate St. John)
A closeup shows feathers and bones (no fur*) but is not very enlightening due to the pellet’s age. Fortunately I stored the pellets in a ziploc bag. After they thawed a small fly appeared inside the bag, hatched from eggs laid on the pellet in much warmer weather. Ewww!
Closeup of peregrine pellet (photo by Kate St. John)
Morela casting a pellet, 17 Dec 2021 (photo from the National Aviary snapshot camera at Univ of Pittsburgh)
Peregrine pellets are slightly longer than a paperclip. Some birds make much larger pellets.
On a hike at Audubon Greenway Conservation Area last Wednesday we found a surprisingly large pellet containing fur, bones and a big tooth. It was so large that we wondered if a bird could produce it. I didn’t pick it up but it looked as though it could span my palm.
Pellet found at Audubon Greenway, 18 Jan 2023 (photo by Kate St. John)Alternate view of pellet found at Audubon Greenway, 18 Jan 2023 (photo by Kate St. John)
The sunrise was gorgeous and cold last Wednesday when a group of us decided to walk at Jennings in Butler County. We saw few birds but there were ice heaves, buttress roots on an elm, and the seeds of old man’s beard (Clematis drummondii).
Ice heave at Jennings, Butler County 11 Jan 2023 (photo by Kate St. John)Elm tree with buttress roots, Jennings, Butler County, 11 Jan 2023 (photo by Kate St. John)
When old man’s beard is in bloom it’s called virgin’s bower, transforming it from a young woman to an old man in a matter of months.
Seeds of Virgin’s bower, a.k.a. Old man’s beard, Jennings, Butler County, 11 Jan 2023 (photo by Kate St. John)
My friends who live north of the city have not seen many dark-eyed juncos at their feeders this winter, but juncos are definitely present at the Frick Park Environmental Education Center. Charity Kheshgi posted photos of our recent trip to Frick.
Golden eagle at the Allegheny Front Hawk Watch, 2 Nov 2016 (photo by Steve Gosser)
19 December 2022
Golden eagles (Aquila chrysaetos) occur worldwide in the northern hemisphere but are quite rare in Pittsburgh though we see them on migration at the Allegheny Front. Their stronghold in North America is in the American West but now the birds face many threats.
Pittsburgh conservation filmmakers, David and Melissa Rohm of Wild Excellence Films, went to Wyoming to learn about the challenges the eagles face and meet the people working to save them. Their film, Golden Eagles: Witnesses to a Changing West, will air on WQED this coming Wednesday, 21 December 2022 at 10:00pm.
In the film we learn that golden eagles prefer wide open spaces without human interference so when we move in, they move out. They’ve disappeared from many areas heavily disturbed by humans and, according to Birds of the World, most North American nesting populations are declining or below carrying capacity due, in part, to anthropogenic related mortality.
Watch eagle researchers rappel down cliffs to band golden eagle chicks. Visit wildlife rehabilitation centers where eagles are treated for lead poisoning. Hear Indigenous people’s connections to the largest eagle in the American West.
(photo of golden eagle at the Allegheny Front by Steve Gosser, map from Wikimedia Commons, remaining images from Wild Excellence Films, click on the captions to see the originals)
Even though it’s December and the weather will only get worse, western Pennsylvania’s bald eagles are gearing up for the nesting season with plans to lay eggs in February.
Established pairs are hanging out together and guarding their territories. Interlopers are testing the limits to see if they can claim an existing site. Subadult eagles are roaming the rivers, trying to steal prey from each other and adults.
Dedicated eagle watchers are already stopping by the viewing sites to catch a glimpse of the action.
At the Hays viewing area on 4 December, Dana Nesiti of Eagles of Hays PA found “both eagles above the nest this morning at first light” (photo at top). On 20 November he saw a prey item stolen twice:
At 9:17am a Peregrine Falcon flew past the nest upstream carrying prey. The male gave chase and they both flew up and over the hillside. 9:35am the male comes flying back carrying prey with a sub adult hot on his tail feathers. They flew down past the stick store and we saw them dive, both eagles came circling back towards the nest. Now the sub adult was carrying the prey and the male was chasing him.
Some kites are birds. More than two dozen species of raptors are named “kite” including the Mississippi kite (Ictinia mississippiensis) of North America and the red kite (Milvus milvus) in Europe. Kite = Bird.
In 1994 dozens of bald eagles were found convulsing, dead or paralyzed near Arkansas’ DeGray Lake. Autopsies revealed the eagles died of a new disease called avian vacuolar myelinopathy (VM) that manifests as brain lesions. The dying spread to Florida, Georgia, the Carolinas and Texas (hashed areas on the map below) and continues to this day. In 2021 scientists discovered what causes VM. It’s a chain of events that begins when we use an aquatic weed killer to control an invasive weed.
VM occurs in watersheds where A. hydrillicola colonizes H. verticillata. Watersheds where VM has been diagnosed (indicated by black crosshatching). Watersheds where H. verticillata has been confirmed to be colonized with A. hydrillicola are shown in red, and watersheds where A. hydrillicola has not yet been observed on H. verticillata are shown in yellow. Watersheds not yet screened for A. hydrillicola, but where H. verticillata occurs, are shown in green. This map, embedded from NIH, is current to fall 2019.
The invasive weed is hydrilla (Hydrilla verticillata) that spreads easily and clogs waterways. It’s a huge problem in many southeastern states, especially in Florida.
Integrated chemical plant management plans to control H. verticillata should avoid the use of bromide-containing chemicals (e.g., diquat dibromide). [The neurotoxin] AETX is lipophilic with the potential for bioaccumulation during transfer through food webs, so mammals may also be at risk.
(photos and diagram from Wikimedia Commons, map embedded from NIH; click on the captions to see the originals)
(*) The mystery was solved when scientists discovered that the toxin came from bromides that did not occur naturally. From NIH, Hunting the eagle killer: A cyanobacterial neurotoxin causes vacuolar myelinopathy: “Laboratory cultures of the cyanobacterium, however, did not elicit VM. A. hydrillicola growing on H. verticillata collected at VM-positive reservoirs was then analyzed by mass spectrometry imaging, which revealed that cyanobacterial colonies were colocalized with a brominated metabolite. Supplementation of an A. hydrillicola laboratory culture with potassium bromide resulted in pronounced biosynthesis of this metabolite. H. verticillata hyperaccumulates bromide from the environment, potentially supplying the cyanobacterium with this biosynthesis precursor.”
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