I feel that this is a candidate Cassin's
Vireo Vireo cassinii; it was moving
in the oaks above our balcony in NW San Antonio, Texas on October
24, 2020. The photos were taken after it flew in close overhead in
response to us playing the Cassin's Vireo call (which seems
virtually identical to the call of Blue-headed Vireo to my ears).
The backlighting makes it hard to accurately assess the tones; in
real life when it was moving around without sky in the background
it appeared to be a bit paler than in these photos:
The image below was taken through foliage, and is washed-out
compared to the photos with a clear view of the bird. While the
primary coverts and greater coverts are washed-out, they appear to
have a similar tone. Also note that the fringes of the outer
Ps are whitish and contrast with the fringes on the inner Ps and
the Ss:
