Here is the note I received last night from Deb at Wildlife Rehab about the little bird.
Sorry I was unable to pop out and say hi to you when you dropped the bird off. The little bird was a warbler (black poll). Basically starving to death, very emaciated and too weak to fly. I was rehydrating him and when I looked in on him that night he had his head tucked under his wing and was sleeping but in the the morning when I checked on him he had passed. Thank you for trying!
Adult wild birds and animals instinctually hide their problems. An animal who is not in peak condition, attracts predators. By the time we get sick or injured adult animals they are in very poor shape. Birds have a very small window to get the help they need because their metabolism is so fast. With mammals, we have a larger window to help them and get them back into the wild. We save the ones we can and hope we can make a difference. It is frustrating to lose these wild souls and a joy to see them get back into a healthy state where they can be free again. That is why doing something is always worth it. So do not feel guilty, because next time we may be luckier. Keep my number and feel free to call me at the vets if I am not at home for ANY wildlife problems.