Bird apps for your smartphone, highlighted on the WSJ:

Audubon Birds: A Field Guide to North American Birds (Green Mountain Digital). Links to eBird for recent sightings nearby. Audio and photos. iPhone, $19.99; Android, $9.99.

iBird Explorer Pro (Mitch Waite Group). Audio, drawings and photos. iPhone, $14.99; Android, $9.95.

National Geographic Handheld Birds (National Geographic Society). Audio and drawings. iPhone only, $9.99.

Peterson Birds of North America (Appleweavers). Based on the well-known Peterson field guides. Links to some eBird information. Audio, drawings and photos. iPhone only, $14.99.

The Sibley eGuide to the Birds of North America (Cool Ideas). Has David Sibley’s highly regarded illustrations. Audio and drawings. iPhone and Android, $19.99.

BirdsEye (Birds in the Hand). Using eBird posts, tells about rare North American sightings and notable ones nearby. iPhone only, $19.99.

BirdLog-North America (Birds in the Hand). Submit sightings to the eBird database. iPhone and Android, $9.99.

BirdJam (MightyJam). A guide to bird songs and calls. Free, but about $90 of software and recordings are needed to set up playlists. Pre-loaded iPods are available. iPhone only.