Developed by researchers from Columbia University, the University of Maryland and the Smithsonian Institution, Leafsnap contains electronic field guides that use visual recognition software to help you identify tree species. Simply snap a photograph of a leaf and the app can identify what type of tree it's from.
Currently, it only includes tree species from the Northeast, but the team is working to include every tree in the continental United States.
Price: Free
Platforms: iPhone, iPad, iPod Touch
Made for both beginners and experts, iTrack Wildlife is a digital guide to animal tracks, filled with photos, track drawings and track descriptions for 65 mammal species. The app also teaches the user how to measure tracks to become a better wildlife tracker. Learn animal tracks for bobcats and red foxes, for example.
Price: $14.99
Platforms: iPhone, iPad, iPod Touch
The National Audubon Society has transformed its numerous paperback field guides into to bite-sized app formats, helping you identify birds, mammals, butterflies, wildflowers and much more. Each guide includes images, blogs, articles and customizable photo albums.
Price: $3.99 - $19.99
Platforms: iPhone, iPad, iPod Touch and Android
More advanced nature nerds, unleash your inner citizen scientist and start tracking invasive species. The What’s Invasive! app shows a list of invasive plants or animals, identified by the National Park Service. Once the user identifies an invasive species, he can pinpoint the exact location via GPS, a photo and any notes he'd like to add.
A collaborative effort by the UCLA Center for Embedded Networked Sensing, the National Park Service and the Center for Invasive Species and Ecosystem Health at the University of Georgia, the app aims to use crowd-sourced data to help eliminate invasive species that threaten native plants and animals.
Price: Free
Platforms: iPhone, iPad and Android
Take your citizen scientist skills to the next level by keeping tabs on everything you spot in nature. Record the plants and animals you find, track life cycle events such as bird migrations and register the location where you see all of this happening. These observations are then aggregated for local, national and global scale decisions.
Price: Free
Platforms: iPhone, iPad, iPod Touch and Android
In the dead of winter, we all crave a little wildlife and outdoor adventure. For a breath of fresh air, invest in apps that could teach you more about trees, birds and everything in between.
See also: 10 Apps for Enjoying the Great Outdoors
Whether you're a citizen scientist or are just beginning to appreciate nature, these five apps can help you identify a tree by its leaf or test your outdoor nature skills.
Do you have a favorite nature app? Let us know in the comments below.