A term used in birding
to describe the process of separating subspecies (or races) of a single species into separate species.
This activity, and it's opposite lumping, are having an effect on the whole process of defining what a species is. For example, many ducks are capable of interbreeding, but they are traditionally considered separate species because they look distinctly different and/or occupy separate world or faunal regions. On the other hand, the number of albatross species is currently in the process of multiplication. Many albatross types look similar and live in the same part of the world and so have been considered a single species. However, closer observation and further scientific studies are coming to the conclusion that plumage variation, breeding location and DNA differences are sufficient to define separation into species.
Some birders are keen on splits as it increases the size of their life lists without any effort on their part. On the down side is the suggestion that we may be put in a position that it is impossible to determine what we have seen without DNA sampling or dissection, as is the case with some species of snail.
The Dutch national birding organisation is well known within Europe for being quick to accept new splits.