Collins Bird Guide is described as 'Birding field guide to Europe' and is an app in the News & Books category. There are three alternatives to Collins Bird Guide for iPad, iPhone, Android and Kindle Fire. The best alternative is Audubon Bird Guide, which is free. Other great apps like Collins Bird Guide are Merlin Bird ID (Free) and eBird (Free).
eBird Mobile makes it easy to record the birds you see in the field, and seamlessly link these observations with eBird--a global online database of bird records used by hundreds of thousands of birders around the world.