On a walk this beautiful Easter morning along an old railroad trail I saw my first Eastern Phoebe this year,
Electronic Bird Guides
The three electronic bird guides for the iPhone/iPod currently available are: the National Geographic Handheld Birds, the iBird Explorer Pro and the Sibley eGuide. They are meant for use in the field to quickly check field marks and are not for identifying a bird from scratch. I believe for most of us the illustrations, along with the audio, are the features by which we judge them. For comparison I looked at the Snow Bunting (which I chose for no particular reason) in each guide and made screen shots of all illustrations for this particular bird. The size of the illustrations are of course limited by screen size and the size of the headers, footers or sidebars which I did not include.
National Geographic HHB
iBird Explorer Pro includes both drawings, and photos whose number are limited by what is in their database. All of them are also available on their website.
The Sibley eGuide shows all illustrations included in the hardcover book and provides the most complete picture of the various types of plumage.
I have used all of them but have come to prefer the Sibley guide over the others. What clinched it for me was the completeness of the audio samples, It alone allows you to scroll through snippets of songs and calls from various locations and seasons whereas the other guides include only one representative audio sample for each species. For example Snow Buntings: songs #1_AK, songs #2_AK, subsong in winter flock_NY, winter flock calls #1_NY, winter flock calls #2_NY, and harsh scold_AK