I have an app put out by Audubon on my Nook which allows me to enter various criteria (size, color, shape, state, month sighted, etc.) which then narrows down the choices. Then, each bird in the database has a description, map of its range, and usually 3-4 samples of its calls. My favorite feature is when I open a bird that is close to but not quite what I am looking for, it offers a choice of similar birds to check out. Once I get a good ID, I can then create Life Lists and add those birds I've actually seen. I have several Lists - one for my own backyard, another for our trip to southern Florida, another for PNW coastal birds, etc. It was an inexpensive app, less than $10. I really like it. Here's an Amazon link to it, although I found it through the B&N Store:
https://www.amazon.com/dp/B004R49A4W/
There are other Audubon field guide apps as well. I downloaded the Wildflower one, but it is not as easy to use as the Bird app.