Displaying an object/image stationary at the bottom of the Vive "screen" or field of view?

Using Unity and SteamVR.

How can I force an object/image to always display at the bottom of the Vive "screen" or field of view?

A good example of this is the Eagle Flight game displaying an eagle in the lower part of the Oculus field of view.

Here is a link to the game play:

[Eagle Flight Game Play!]

Note the head remains stationary.

Thanks