I saw a Black-capped Chickadee today that has a bad leg. It just dangles down, and doesn't seem to function at all. It is so hard to watch because I know that especially in winter, these little birds need to be in tip-top shape.
He's using the birdfeeders, so I know he has an easy source of high quality, high calorie food and doesn't have to spend extra energy in search of food. The feeders are filled with WBU No-Mess NM, a blend with shelled sunflower seed, shelled peanuts and tree nuts, which may help him out in his struggle to survive.
Chickadees will take a seed from a feeder and fly to a nearby perch. Clutching the seed between both feet, they will use their little beak to open the shell and consume the seed. This little guy can only clutch the seed with his good leg, so I'm hoping that the absence of the shell makes it easier for him to consume the seed meat.
He's a strong flyer - nothing wrong there - but his landings are a bit awkward as he has to land on just one leg.
If the injury is permanent, he'll be at a huge disadvantage. Bird mortality is high for even a healthy bird; take away the function of one leg and the odds are even more stacked against its survival.
If he has trouble eating, he could lose precious body fat because he can't take in all the calories he needs. If he doesn't have enough fat, he could perish over a cold winter night. Though his flight seems strong, his landings are off, which could make him more vulnerable to predators. His dangling leg could become an impediment; it could catch on a branch and make him unable to disentangle himself.
I'll keep an eye out for him. Maybe it's just a temporary injury that will resolve itself over time, and he'll do fine during the recovery process. But just like I'll never know how the injury occurred, I'll probably never know his ultimate fate. I'll do what I can by keeping easy-to-eat shell-less sunflower seeds and peanuts out for him and in birdfeeders that don't require him to cling. Every day I'll just look for him and hope for the best for this cute little fighter.
UPDATE: April 28, 2014
I saw my bad-leg chickadee occasionally through the winter and he just checked in at our birdbath today! We had a pretty rough winter, so it's good to see that he beat the odds and made it to spring. You gotta love these little feisty birds!!