Collectibles are what give our game its replay value. The collectibles are spread around the level and due to the field of view it is impossible to collect all of them in one play through while still keeping birdman in view for the time required. To get them all, you have to keep playing.
Field of view timer
I created a bar as part of the UI which decreases when the camera's field of view is not colliding with birdman. When the player begins looking at birdman again, it will increase however slower than it decreased.
I'm not an artist. I don't think I need to say this as you can see from the images taken from Google Images!