Gary disagrees that the LCD is inaccurate on the back of a DSLR. The key is to look in a shaded area and get into the menu to adjust the LCD brightness. You can do a little bit of calibration by adjusting it while looking at the image on the computer. You can get pretty close matching the image. He also recommends adding a Delkin PopUp Shade to your viewfinder.
Check out Gary's photography of birds here.