11 June 2023

This spring Downtown Pittsburgh’s peregrines were so confusing that for two months we weren’t even sure of their age and sex. By now we know that the male at Third Avenue is Terzo and the dark brown bird is female. Why is this bird so dark? The mystery is intriguing.

Wrong ID for the dark bird:
In early April Jeff Cieslak and I were both convinced the dark brown bird was a one-year-old male because we saw it enter the Third Avenue nest carrying prey even though the eggs had not hatched yet. After all, male peregrines bring prey to incubating females and immature birds have brown plumage … don’t they?

Solve the easy ID first: Who is the banded white-chested bird?
Jeff Cieslak’s April and May photos show that the gray-and-white adult has black/red bands. Also, several viewers remarked that the bird’s face is like Terzo in other photos. This bird is the male, Terzo.

Is the dark bird immature?
No. Adult plumage has horizontal stripes on the flanks and belly, immature plumage has vertical stripes. Compare these side-by-side adult and juvenile peregrines photographed at Third Avenue.

Is the female completely dark brown? No. This photo of her back shows it is grayer in color than her belly.

Why is this bird so dark?
I sent photos to Art McMorris, retired PA Game Commission Peregrine Coordinator, and asked: “This adult at the Third Ave nest site Downtown is very brown and not banded as far as we can see. It doesn’t have juvenile vertical stripes on flanks and chest. I don’t know what to make of this coloration.”

Art’s reply includes a Peregrine Reintroduction discussion in the third paragraph:

This is indeed a very puzzling-looking bird. I’m looking at these 3 photos and the photo Jeff Cieslak took on 4/14. All show the horizontal banding typical of adult peregrines, not juveniles. But it is very brown, atypical of adults. It is much grayer in the third photo you sent; nowhere near as brown but still very dark.

Structurally, it looks like a typical peregrine to me.

Taking all of this together, I’d say it is reminiscent of pealei [Pacific Northwest subspecies]. Pealei is non-migratory, so I wouldn’t suggest that it might be a bird from the Pacific Northwest, but pealei is also one of the 7 subspecies used for captive breeding and release. And occasionally genetic recombination in the wild population results in birds with unusual coloration. I know of 2 cases of peregrines that looked exactly like pure tundrius, but their parents had the typical appearance of the re-introduced population, which strongly resembles eastern anatum (but is not anatum; it’s an intergrade of the 7 subspecies). One of those tundrius look-alikes was from the Gulf Tower, quite a few years ago when the population was still small.

So, my best guess is that this bird is an adult peregrine in which recombination has resulted in homozygosity of some alleles from its pealei ancestors. And the downtown bird is fertile, inconsistent with it being any kind of hybrid.

It will be interesting to see what this year’s young look like when they molt into adult plumage. But unfortunately, we’ll never know.

— Paraphrased email from Art McMorris, 4 June 2023

What other clues do we have about this bird?
Art has so much experience with peregrines that he also said: “Earlier the brown bird was called the male, but the feet look female to me.”

Yo! Big feet?!

Just when I think I’ve got it all figured out, peregrines surprise me again.

(photos by Jeff Cieslak and Kate St. John)

4 June 2023

Peregrine falcons have nested in Downtown Pittsburgh since 1991 and though the players have changed they are very loyal to the territory. From 1991-2011 they nested at the Gulf Tower but since 2012, with three exceptions, they have nested at the back of a building facing Third Avenue. 2023 is their ninth nesting season at this site.

Yesterday morning I stopped by Third Avenue to see if any peregrines were visible and was lucky to see the entire family. Three youngsters perched at the ledge opening (photos at top) while their parents watched from above on the crossbars. The brown youngsters are exercising their wings and will fledge this week.

The adults have been a mystery. On 3 March Jeff Cieslak photographed an adult-plumaged pair: an unbanded female (not 16-year-old Dori who was banded) and a male who did not show his legs. When Jeff returned on 14 April he saw a nest exchange that appeared to be a male (unbanded in dark brown immature plumage) bringing prey to a female (banded & in adult plumage). The behavior told us who was who. Or did it?

Here are photos of the adults.

Adult-plumage bird on 18 May and 3 June 2023. Jeff re-checked his photos and saw that this bird has black/red bands and several viewers have remarked that the bird’s face is like Terzo’s. This is the male, Terzo.

Photos of the dark brown bird on 28 May and 3 June 2023 are more of a mystery. The flank stripes are horizontal so this is adult plumage. This dark brown unbanded bird is the female. More on her color in a future article.

Stop by Third Avenue in the next few days to see the youngsters fledge.

(photos by Kate St. John and Jeff Cieslak)

30 May 2023

Last Wednesday, 24 May, Mark Vass drove down the Monongahela River valley looking for birds and checking bridges. In West Brownsville he found a peregrine perched under the US Route 40 Lane Bane Bridge. Mark’s checklist and photo set off a quest to find the nest (https://ebird.org/checklist/S139102470)

Jeff Cieslak made the trip on Friday 26 May and found the nest hole and a pair of peregrines carrying food to it. The female is peachy with heavy dots, the male is whiter. Neither bird is banded. (My male-female assessment is based on the tendency of mid-latitude males to be paler than females. Notice that both have the adult plumage trait of horizontal stripes on their flanks.)

Alyssa Nees and Fred Kachmarik visited on Memorial Day, 29 May, and counted a family of five — two adults, three chicks. Alyssa’s photos show an adult in the nest hole …

… and a chick clearly visible (red circle) with fluffy white top of head, feathered face and brown back. The arrow points to the tail of an adult watching from above.

Fred’s photos of the chicks include an older chick and a fluffy young one:

Where are these peregrines located?

The Lane Bane Bridge, carries US Route 40 over the Monongahela River from West Brownsville, Washington County, to Brownsville, Fayette County PA. Its construction is very similar to the Graff Bridge at Kittanning, PA, which has its own nesting peregrines.

A truss structure spans the river and ends at a pillar on each side. As far as I can tell from the photos, the nest appears to be close to the pillar. So these birds are nesting in Washington County, PA.

Interestingly, when Google Street View cameras drove by on the West Brownsville side this month, the cameras “saw” a bird perched on the superstructure near the pillar. I’ll bet this dot is a peregrine.

Thanks and congratulations to Mark Vass, Jeff Cieslak, Alyssa Nees and Fred Kachmarik for finding and documenting this peregrine family.

If you’d like to see the birds yourself, Jeff provides a map.

p.s. Could there be another peregrine nest at the next bridge three miles away? Nope. The Mon-Fayette Expressway bridge is solid concrete. Click here to see a screenshot of the Mon-Fay bridge in Google Street View.

(photos by Jeff Cieslak, Mark Vass via eBird, Alyssa Nees, Fred Kachmarik via eBird, Wikimedia Commons and screenshots from Google Street View)