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.