The Bird's-Eye scrollbar gives you the really big picture. It shows the relative zoom and position of the waveform window to the total data. As you navigate through the data, you can look at the Bird's-Eye to see exactly where you are in the data and how fast you are progressing through it. You can also use it to scroll through the data, jump to another area or jump directly to a marker.
The total data is shown as a transparent box with an outline. When zoomed out, the portion of the data being viewed in the waveform window ("screen" area) is indicated by a rounded rectangle with vertical dividing lines corresponding to the 10 time divisions of the window.
Dragging the screen area of the bird's-eye will scroll the window view.
When the window is zoomed in on a small percentage of the data (usually the case) the waveform screen representation becomes a pointed tag with the point indicating the center of the screen in the total data ("you are here" indicator).
Each of the markers (and its complement if split) are also shown with color-coordinated lines. If the currently selected marker has been Split, the area between the marker and its complement is indicated with slanted slash marks in the color of the marker (see Using Markers).
You can click on the Bird's-Eye scrollbar to jump to any position in the data. If you hold the CTRL Key while clicking near one of the markers, the waveform will "snap" to that marker's position. However, since the amount of time captured is so large compared to the available pixels on a monitor, you may not notice when several markers are represented by the same pixel. When several markers are represented by the same pixel the first represented marker will be chosen.