One of the most comprehensive bird watching guides out there is the Sibley eGuide to the Birds of North America.
It's a $20 download for both iOS and Android users, but there is a free light version available.
The full app is basically the popular field guide in digital form in its entirety.
There are more than 800 species listed with nearly 7000 images and a couple of thousand different sound recordings.
If you're interested in identifying songbirds, download the $13 Warbler's app onto your iPhone or iPad.
This app has taken great care to include sonograms to show song structure, and ID points for each audio clip.
Through the app, you can also play back clips in half time to analyze the call and even search the extensive database with key words to find the species you're trying to identity.
And finally, BirdsEye is a great free app for finding out where to view birds near you.
Using your phone's GPS, it will tell you the 100 most common birds in your area and can drive interactions to locations of recent spottings.
In San Francisco, I'm Kara Tsuboi, cnet.com for CBS News.