From the basic shape and posture of the bird, we can tell that it is some sort of heron. The colors and the fact that the picture was taken in Georgia in June eliminate all possibilities except for Green Heron. In this case, it is a fledgling.
The first thing to note about this bird is the size compared to the branch. We can eliminate many bird species by the size alone. The second major thing to note is that the back of the bird is almost completely one color. That greenish color is a distinct field mark among ABA area birds. The third thing to note is the glossy sheen on the bird. Which birds might have this? Well, crows sometimes have a glossy sheen, but the distinctive tail rules that out—check out those two pointy feathers. Think about behavior for a minute: what bird of this size would be in this kind of position? The way it is perched reminds some people of a woodpecker. What woodpecker has these distinct field marks? The crow-like, large, and oddly behaving Lewis's Woodpecker is our final answer for this photo.
Here we have a dull looking yet medium-sized passerine. The drab coloration could be because the bird is a female or a juvenile. There is also some obvious streaking on the chest, which is important to consider. You can rule out a decent number of birds by just seeing if it has streaking or not. The overall posture of the bird suggests sparrow or towhee, which would be a correct assumption. Guided by shape and posture we will go with towhee. This is most likely a juvenile because there are no ABA-area male towhees that have these colors and patterns. So now that we know its a juvenile, we start to narrow things down a bit. You might be able to notice the white on the wings. The white is too thin and tiny to match the wing bars of a juvenile Eastern Towhee. This leaves us with four other possiblities. We can eliminate Canyon, California, and Green-Tailed towhees because the juveniles have no streaking on the chest, and the streaking on Abert's is not as bold as this bird. Final answer: juvenile Spotted Towhee.
About the authors: Sam Brunson and John Mark Simmons are avid birders and founded the website Two Birders and Binoculars (www.twobirdersandbinoculars.com). They have birded together for a long time and most recently won the Georgia Youth Birding Competition in 2012.