Non-colony observation. Small flocks and individual TRBLs were commuting east-west (both directions) over the north-south hill along which Ponchetti Road runs. The "Mesa Grande Road" colony is just to the west, but I did not see birds there (but doesn't mean it wasn't occupied). Potentially suitable habitat can be found in the low-lying areas both east and west of the ridgeline.
[note there is no way to indicate "none" in the "Primary Substrate" data field]