Bonus Downloads
Bonus downloads are free content, such as animals and scenery, that you can download from within Zoo Tycoon 2.
To download bonus content:
1. Be sure you are connected to the Internet, and then start Zoo Tycoon 2 or one of the expansion packs, such as Zoo Tycoon 2: Endangered Species.
2. On the main menu, click Downloads. The bonus content you can download appears on the screen. Click the Download button beside the bonus content you want to install.
3. After the download is complete, exit and restart the game. Then have fun playing with your new content!
If some of this bonus content is not listed on the Downloads screen within the game, you may need to install the Zoo Tycoon 2 patch.
There's what the official ZT2 website says about there downloads
