Bird ID in "3D" on iPad or iPhone

First there were the little arrows used by Roger Tory Peterson in his classic and important birding guide book. The arrows marked important identification clues for the bird you were watching.

Then, identification books with photos. Then, better artwork. Today, many books, each seeking to catch your eye and help you find a way to name that bird.

Now, technology has gone one step farther. Or two or three.

Princeton University Press has released a bird-identification app for iPhone and iPad. It replicates in electronic form the recently published book "The Warbler Guide" by Tom Stephenson and Scott Wittle.

It also animates the book, and gives it sound.

The app offers what Princeton calls 3D images. You place fingers on an image of the bird and rotate. You can see the bird from any angle — up, down, profile, three-quarter view, whatever meets your needs. It's sort of magical, simple and familiar if you are savvy about these devices, a frequent user, but certainly novel when it comes to birds.

There are photos (not all in 3D, but photos from several angles) of male, female, and juvenile plumages. You can view similar species as you view your target bird, make comparisons quickly, on one page. There are photos to help you age and sex the bird. There is text to explain similarities and differences.

There is a clever overview page that shows the bird in silhouette, drawings offering a summary of color pattern, including under-tail view, a map showing broad distribution of the species, and even an image of a tree and bush colored to tell you what part of that vegetation the bird can be expected to use (lower portion of tree, middle, top).

There are excellent range maps, large and well-colored.

And songs? Vocalizations? For the American Redstart, for instance, there are nine offerings: chip call, flight call, and seven types of song. Songs of all North American warbler species are on the same scrolling page, arranged alphabetically, so if you want to make voice comparisons it is easy to do. The app describes the song as buzzy, clear, trilled, or a variation of those choices. Pitch trend — up or down — is shown.

If you would describe the song as having, for example, three sections, click on "three" under the choice "song sections" and all calls having three sections appear alphabetical by species.

You can arrange all of this information by color groups, alphabetical, or in taxonomic order.

The app costs $12.99. The price is less than almost any ID book, and offers much more for your money. Purchase is made at the Apple Store.

A consideration would be convenient use of either the iPhone or iPad as you seek ID help. At home or in the car? No problem. In the field, certainly more convenient with the phone, although the size of the images could be an issue (it would be an issue for me). My purchase was for the iPad version. Will I take the iPad into the field? We'll see.

Regardless, this is an amazing collection of identification information for our warbler family. If anyone else wants to do this, to publish what they might consider an improvement, they will have to work very, very hard.

Everything you might want to know can be found at https://www.youtube.com/playlist?list=PLG9b0fRtVfA3e1R74BozvgK7x3corNuqx

Below, an image from one of the app's pages. Photos at the bottom illustrate species that might be helpful for comparison. Image is to size for the iPad.