Here is a good reference for you.
http://www.sibleyguides.com/David Sibley does one of the best jobs on writing Bird ID guides. He has an Eastern, Western and a large combined Eastern and Western book,, for those of you who might like a field guide to take on the road with you. There is an app for this for Andoid's on his web site. Don't know anything about the app. Have all 3 of those books and a couple of other books he has written.
This one is better if you subscribe as it gives you more information. But you may not need that much data.
http://bna.birds.cornell.edu/bnaI just binged (google) Bird Identification....had a lot of options - here is one of them. Identify birds by color. It has the yellow-rumped warbler (commonly referred to as a butter butt) but only shows you one of the subspecies - a book would would you both the Myrtle and the Audubon bird and depending on which bird you see you could ID as they are different. But you have to search thru these birds based on their descriptions. I just like the books better - said the old birding lady!
http://www.birdnature.com/identification.htmlMy take is if you are intersted, go to a used book store and get a good book for the area you will be birding in. The computer doesn't give you the option of looking at many birds all at once and checking the map location......just my 2 cents. Any way surf your hearts out.