The presence of lichen or moss on backyard trees can understandably be concerning at first. Lichen is a combination of algae and fungus that lives on any number of solid, undisturbed surfaces, ...

A hand examining moss on a tree - Artmarie/Getty Images ...

Have a question about this project? Sign up for a free GitHub account to open an issue and contact its maintainers and the community.

The most widespread of our three species of rosy-finches, the Gray-crown nests from the islands of western Alaska south to the high mountains of California and northern Montana. Different populations ...