Bank or Tree Swallow - Marin County, California, USA (1 Viewer)

[rkj]

I saw this swallow (or maybe more than one) at Las Gallinas in Marin County, California, 4 June 2022. At the time I thought it was a Bank Swallow (known to some as a Sand Martin), but now I am wondering if it may have been a juvenile Tree Swallow. Bank Swallow would be unexpected at this location. There were certainly juvenile Tree Swallows there and at least one had a fairly distinct breast band, at least in some postures - see the first two photos. But a bird flying around the same area seemed to have a much more distinct breast band - see the last three photos. Other features said to distinguish the two are unclear to me. I would be grateful for any insights anyone would care to share.

 

[KC Foggin]

For me, the first two images are a Tree Swallow family and the last 3 are Bank Swallows.

 

[A2GG]

I agree with KC. One of the young Tree Swallows has a pretty well defined band which makes this more difficult though.
The bird in the last 2 photos has a pretty strong breast band and it has that 'chubby' look of Bank Swallow, so I'll stick with it.
I've only seen Bank Swallows twice, so not a lot of experience here.

 

[Microtus]

To me, all the birds are Tree Swallows. #3 is a young Tree Swallow; it looks like the ones begging from adults in #1 and #2.

"Juveniles are brown above and white below, but some juveniles and females can show a weak, blurry gray-brown breast band."

Tree Swallow Photos and Videos for, All About Birds, Cornell Lab of Ornithology

Handsome aerialists with deep-blue iridescent backs and clean white fronts, Tree Swallows are a familiar sight in summer fields and wetlands across northern North America. They chase after flying insects with acrobatic twists and turns, their steely blue-green feathers flashing in the sunlight...

www.allaboutbirds.org

I'm not seeing the white swoosh of Bank Swallow on the side of the neck in photos #3-#5, and it looks like there is yellow at the corners of the bill indicative of a very young bird. The darker brown feathers around the eye say Tree Swallow to me.

 

[A2GG]

I'm not seeing the white swoosh of Bank Swallow on the side of the neck in photos #3-#5, and it looks like there is yellow at the corners of the bill indicative of a very young bird. The darker brown feathers around the eye say Tree Swallow to me.

I forgot about the whitish 'swoosh' on sides of neck. There doesn't look to be an obvious swoosh in #5. I'm not sure if I see the yellow in the bill, but the breast band does look like it gets more faint in the center. You're probably right these could all be Tree Swallows.

Edit: after zooming photo #5 I can see some hint of yellow in the bill.

 

[AveryBartels]

Proportions are also better for Tree. Bank are quite slender with narrower wings whereas the in flight images show a stockier, broader-winged swallow more in line with Tree

 

[A2GG]

Proportions are also better for Tree. Bank are quite slender with narrower wings whereas the in flight images show a stockier, broader-winged swallow more in line with Tree

I've always thought they are 'chubby' and smaller compared to Tree Swallows.

Cornell Lab seems to give conflicting descriptions:

under the first photo it states "small songbird with small head ..."

scroll down under 'Size and Shape' and it states "A small swallow with a chunky body, large head ... "

Bank Swallow Identification, All About Birds, Cornell Lab of Ornithology

The svelte and speedy little Bank Swallow zips through the air with quick twists and buzzy wingbeats. Look for them in chattering nesting colonies dug into the sides of sandy cliffs or banks, or pick them out of mixed swallow flocks as they catch insects over the water. These birds occur on all...

www.allaboutbirds.org

 

[rkj]

Thanks to you all. It seems clear now that it is probably a juvenile Tree Swallow.

 

[birdmeister]

I think of Bank Swallow's head as a little "whale head", almost like a Beluga. Not that it's proportionally large, but its rounded profile gives it that submarine sort of look.