The illustration consist of two parts:

1. Left side image is a spruce tree with a height of 18 meters.
2. Right side image has three species of warblers:
3. Cape May Warbler- Feeds between 12 to 18 meter height of spruce tree.
4. Bay-Breasted Warbler - Feeds between 6 to 12 meter height of spruce tree.
5. Yellow-Rumped Warbler - Feeds below 6 meter height of spruce tree.