At $2.99, it's a steal. The "Audubon Birds: A Field Guide to North American Birds" is a field guide for Android smart phones and iOS iPhone, iPad or iPod. The app contains more than 770 species of North American birds in its list, each with descriptions, images, details on behavior, bird calls, habitat, nesting times and location, and more. It now comes with Find Birds where you have access to recent sighting, locations of notable and rare birds, and maps with birding hotspot.

Audubon has plenty of other guides, including the Florida Nature Guide ($9.99), mammals, trees, fish and insects.