This Yellow-billed Cuckoo was photographed at Rosehill Cemetery, Corpus Christi, Texas on May 05, 2018. It is unusual on two counts:
Firstly the orbital rings have no detectable yellow in them, appearing as dark blackish brown.
Secondly the chin/throat area is washed with a warm buff tone, plus there are tinges of a yellowish-buff on some areas of the lower underparts.
The buff tones are not a camera artifact, and in real life were clearly visible even at moderate distances - it is what caused me to pursue this bird in order to obtain photos.
It is possible that this underpart appearance is due to staining, but regardless, this bird provides a datapoint showing that Yellow-billed Cuckoo can have a fairly obvious buff tone on at least parts on the underbody. This might be helpful when assessing claims of rarer taxa, e.g. Mangrove Cuckoo and perhaps Black- and Dark-billed Cuckoos since young Yellow-billed Cuckoos have a dark bill for a short period after fledging:
The image below has been lightened in order to better show the orbital ring: