A birding life list is a compendium of all of the avian species which an individual birder has positively identified while bird watching. Given that there are over 9,000 bird species in the world, a birder is unlikely to end up with a complete list of every bird on Earth, but a birder can accumulate a lengthy life list if he or she starts birding early and keeps the list well organized. The organization of birding life lists has been greatly facilitated by the advent of computer programs specifically designed for managing life lists, along with Internet sites for birders to exchange information with each other.
As a general rule, a birder must be thoroughly confident about the identification of a bird before placing it on his or her life list. With some bird species identification can be obvious. Others, however, are more complex, as many bird species closely resemble each other, or have different stages of plumage which can fool casual observers. The birder closely examines the bird while consulting a field guide, and may take a picture as well to confirm the identification. If the birder is confident about what he or she has seen, the bird will be added to the life list.
There are a number of ways to organize a life list. The classic technique is to put a life list in chronological order, and many birders have binders documenting sightings from individual trips, like a journal, on unique pages which are later entered into a computer. Most birders also like to sort their life lists by order, family, genus, and species, so that they can look at the life list and take note of all of the ducks they have seen at a glance, for example. This type of organization also highlights the close link between many bird species which may seem radically different, but are actually related.
In addition to serving as a record of all the birds someone has seen, a life list is also like a diary of the birder's life. The life list includes the location and time that a bird was spotted, allowing birders to look up all the birds seen on a trip to Guatemala, or remember a remarkable trip to Thailand. Especially when a birder has seen a rare species, an entirely new species, or a bird thought to be extinct, a life list can be an object of pride and even some bragging.
The networking of life lists through the Internet also serves the scientific community. Ornithologists can use life lists to track species all over the world, looking for areas where unique species are frequently sighted and identifying species which may be at risk. Life lists can also identify scientific discoveries; on occasion, a birder who includes a photograph of the bird on an Internet site has been informed that he or she has actually found a new species of bird, which is a cause for celebration.