A life list is a list of particular species seen in a particular time frame, most commonly the life of the observer but some are for a year or a season. Most commonly associated with an individual bird watcher a life list would be a list of all the species of birds seen by that birder and would likely include date and location seen, gender of bird, mature or juvenile status, notable behavior, etc.
Life lists are also maintained for certain places, for example a given bird feeder's life list would be the birds observed on or about that feeder. Many web cams focusing on bird feeders also maintain online life lists.
Life lists are also maintained for other groups of plants and/or animals. For example mammals, reptiles, butterflies, trees, or wildflowers.
Life lists chronicle a user's observations and perhaps travels as well as species observed. They help to organize and categorize on paper or computer and in the user's brain what they have observed. They are useful for setting goals (like I want to add a bald eagle to my life list and am planning an outing to a local area where they are frequently observed). Life lists also celebrate certain milestones, for example the 100th bird added to a life list.
I am new to bird watching and my life list is quite short - 16 species seen this year in my yard after I began active bird feeding and observing. I've certainly seen more species than this but I couldn't identify them.
My birding life list is at 60 as of April, 2004. This is still considered fairly low, even for local birds.
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