This Empidonax Flycatcher was photographed at the Birding Center at Port Aransas, Nueces County, Texas on September 07, 2013. I feel it suggests "Trail's" Flycatcher (most likely Willow), yet the mandible caught my eye in the field as it appeared to be all-dark...? Or am I getting it wrong (again) and this is a chunky Least Fly with crest, long primary projection, and honking bill!?:
This is the only image that indicates the mandible is not dusky, but even here it does not look to be the typical bright fleshy-orange of Trail's; in life while under observation it looked dusky all the time:
A different bird at the same location, I feel that this is a Trail's-type (probably Willow) but note that it appears to have a dark tip to the mandible:
