Black phoebe pair in Larimer County

[Nicholas Komar]

Today I had the opportunity to study a reported pair of Black Phoebe at Lions Open Space in northwest Fort Collins along the Poudre River, just south of LaPorte, Colorado. These phoebes have generated some local controversy related to genetic lineage or parentage. After studying them this afternoon I noted that both emitted call notes identified by Merlin as Black Phoebe. Both had black hoods that contrasted with paler gray back and both had slight paleness to blackish chest. This paleness suggested genetic influence from eastern phoebe, which would not be unexpected as Fort Collins is in the hybrid zone. However, perusing photos of Black Phoebe in eBird, I found that these pale features are commonplace among Black Phoebes throughout their range, including birds from west coast states not in the hybrid zone. So while I admit that these two birds are not as dark as the darkest Black Phoebes, I think they fall within the range of variation that is acceptable for the species. Perhaps this pair of phoebes will breed in the area, possibly at the Overland Trail bridge over the Poudre River. I know of one previous breeding record for Black Phoebe in Larimer County. There may be others.

Nick Komar
Fort Collins CO

[Bryan Tarbox]

Hi Nick (and others)

Some of the earlier photos when there was only one known phoebe had me agreeing with you, especially Adrian Lakin's photos from March 30th (https://ebird.org/checklist/S132243026). However, I hadn't kept up with the newer photos once it was confirmed there were two birds until after seeing the birds myself today. Upon seeing them at close range in good light, they immediately gave me Eastern Phoebe 'vibes', due to the warm brown tone of their dark parts and the faint yellowish tinge to their light parts, as well as what felt like a more upright posture.

I dug through a bunch of photos myself and like you said, the paler brown tones are not outside the range of variation for BLPH, however, I'm not so sure about the yellow tinge. There are some CA BLPH that look a little yellow but I can't find any where I'm sure it's not just the lighting, whereas I'm pretty sure it's not just the lighting on our birds here in Fort Collins.

More importantly, after reviewing others' photos of the two birds here, a number of them appear to show some smudginess along the breast band and pale feathers on the breast and throat. It's not nearly as obvious as other photos of hybrid BLPH x EAPH on eBird, but it's there (see below). Even when CA BLPH are pale, the breast band is always completely clean and there's no sign of pale feathers above it.

https://ebird.org/checklist/S132897934

https://ebird.org/checklist/S132250660

https://ebird.org/checklist/S132733061

https://ebird.org/checklist/S132825745

https://ebird.org/checklist/S132811181

https://ebird.org/checklist/S133094297

I think there probably is at least one hybrid, and the second bird (perhaps the one Adrian photo'd on the 30th) could be pure BLPH but hard to say. Would be nice for someone to get a bunch of photos of each individual to compare - when at Bingham Hill Cemetery they seem more cooperative for photos fwiw.

Relatedly, EJ Raynor's photos of a hybrid from 2021 at Watson Lake look much more obviously like a hybrid than either of this year's birds, imo (https://ebird.org/checklist/S107320617). Those photos also look quite different from the handful of (not super clear) photos of a supposed Black Phoebe from Lions Open Space that same year (https://ebird.org/checklist/S87986010 & https://ebird.org/checklist/S88159831). I saw that bird but didn't take photos, and from what I remember it didn't strike me as unusual for BLPH. Perhaps there was one of each then?

Bryan Tarbox

Fort Collins, CO

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