Yep...those are melanistic thayeri....
And if your thayeri were eating up till winter they still should be feeding well if there is a good thermal gradient.......90F on the hot side and 70F on the cool side......Plus...Make sure you provide them a moist place to hide (damp spaghnum moss)......Humidity and temp choices are detrimental mexicana husbandry.......
I hope you get them feeding again soon....try the brained pink trick under a dark bowl.....Also live/brained works well even though some folks think it is cruel......You gotta do what you gotta do IMHO.....sorry PETA.....lol