In North America it is more often called chasing, though the British usage is starting to catch on there, especially among younger birders. The term twitcher, sometimes misapplied as a synonym for birder, is reserved for those who travel long distances to see a rare bird that would then be ticked, or counted on a list.Birdwatching, or birding, is a form of wildlife observation in which the observation of birds is a recreational activity. It can be done with the naked eye, through a visual enhancement device like binoculars and telescopes, by listening for bird sounds.
Indeed, in 1969 a Birding Glossary appeared in Birdingmagazine which gave the following definitions:
Birder. The acceptable term used to describe the person who seriously pursues the hobby of birding. May be professional or amateur.
Birding. A hobby in which individuals enjoy the challenge of bird study, listing, or other general activities involving bird life.
Bird-watcher. A rather ambiguous term used to describe the person who watches birds for any reason at all, and should not be used to refer to the serious birder.— Birding, Volume 1, No.2Many birdwatchers occupy themselves with observing local species (birding in their “local patch”), but may also make specific trips to observe birds in other locales. The most active times of the year for birding in temperate zones are during the spring or fall migrationswhen the greatest variety of birds may be seen.Birdwatchers may take part in censuses of bird populations and migratory patterns which are sometimes specific to individual species. These birdwatchers may also count all birds in a given area, as in the Christmas Bird Count or follow carefully designed study protocols.Due to their accessibility and ubiquity, birds are a useful tool for environmental education and awareness on environmental issues. Birds easily transmit values on respect to nature and the fragility of ecosystems. Birding as a competitive event is organized in some parts of the world. These are found to be more exciting by some. The birding competitions encourage individuals or teams to accumulate large numbers of species within a specified time or area with special rules.As the numbers of birdwatchers increases, there is growing concern about the impact of birdwatching on the birds and their habitat. Birdwatching etiquette is evolving in response to this concern. Some examples of birdwatching etiquette include promoting the welfare of birds and their environment, limiting use of photography, pishing and playback devices to mitigate stress caused to birds, maintaining a distance away from nests and nesting colonies, and respecting private property.*** based on a Wikipedia article