Most of you are likely familiar with the photoshop eye dropper tool, which lets you sample any color in an image. You may want to do this in LR as well, but it is not immediately obvious how to do this. The eye dropper is available in the gradient and adjustment brush local tools. Select either one and then select the tint icon.
The trick is to mouse click and drag the eye dropper onto the image.
As you can see, the eagle wing color is now shown in the swatch color array. Another handy to know tip is how to select the color complement if you want to neutralize a color. In this case the hue is 211°. The complement is 180° around the color circle, or 31°.