There are at least fifty types of shorebird species in North America, not including vagrants; these are birds that are blown off course during high winds or storms, and others that just happen to drop in for a short visit. These birds are found throughout North America and most of them can be seen along the water's. Some prefer salt water and can only be seen on the sandy and rocky coastlines of the oceans and mudflats, while others may be found feeding in salt water and fresh water, depending on the season. Shorebirds are among the most difficult birds to identify. Some species are quite similar to other species and their calls are the only true way to distinguish one from the other. Most of these birds will change from a colorful plumage in their breeding season to dull greys and browns in the fall and winter months.