Bird Data is a reference source for over 10,000 species of birds, including extinct species. It combines information from the IOC 11.2 taxonomy, IUCN Red List, and other databases for all of the world bird species. Data includes bird names in seven languages, subspecies, ranges, alternate names, IUCN status, countries, and taxonomic hierarchy.
The app has links to thousands of bird songs, bird calls and images (over 7,000 species) that can be downloaded to the device. With these features, the app could be used as a field guide, and it is quite complete especially for countries in the Americas.
An interactive map connects to eBird hotspots and eBird bird sightings in the last 30 days.
The app is free but a small donation through an in-app purchase is appreciated.