Juncos use their feet more than many birds, not just to perch but to hop about while feeding. Their legs and feet, viewed close, are a contradiction: incredibly slender and fragile-seeming, but also covered in a hard, scaly, tough surface. You hope for their sake that the fragility is the illusion and the toughness reality, but of course each is a little true.
LANK has a permanently bent toe on his right foot. When he perches, his weight rests on what should be the top of the toe, and I imagine the same is true when he stands on the ground.
–AY has a much more extreme foot injury. At some point on the past, his left ankle (or the leg near the ankle) must have been broken, and the injury set wrong. The area is healed and solid now, but the foot is sideways.
(–AY’s “name” is odd because I didn’t want to put bands on the abnormal leg, so only his right leg is banded.)
That’s certainly bad for –AY; it must make life more difficult. But think: his leg was broken, and he lived with it long enough for it to heal. His foot is sideways, but callouses on the downward side show that he clearly uses it, albeit probably as a sort of peg leg now.

Closer view of the foot, showing callouses on the downward side. The sun makes the foot look red but it wasn’t in reality.
And the most important things: both LANK and –AY are defending territories. Both weigh about average, so they can’t be starving. Watching both before they were captured, I didn’t notice anything strange in the way that they moved.
Juncos are fragile, and sometimes they break. But they are also tough: sometimes, they can keep going anyway.
Mmm … Up close, however small, those therapod talons …
Oh yes!
I hope you are able to watch him for a long time and observe how he deals with his handicap.
Me too! I’m definitely going to keep looking for him.
Just noticed a Junco (quite a few visit my yard) may have one leg. 😕