If you are using an iPad you may not be seeing it (BirdsEye Birds Finding Guide) because the App Store is only showing you iPad specific apps. BirdsEye runs great on your iPad, it is not fully optimized for the larger screen and isn't displayed in the App Store as iPad app. To see it you'll need to switch your App Store view to iPhone(only) apps.
Here's what to do:
* Open Apple App Store
* Type "BirdsEye" in the search window
* Select iPad Only/iPhone Only tab at far left on menu bar
* Change it to "iPhone Only"
* Select "BirdsEye Bird Finding Guide" from the list of apps