Original sentence: Around 550 bird species have been recorded in Britain; 250 have regular breeding or wintering populations, or are common migrants, and a further 50 are "scarce migrants".The remaining 250 species are those which the BBRC assesses
Edited sentence: Over 580 bird species have been recorded in Britain; 250 or so have regular breeding or wintering populations, or are common migrants, and a further 50 are "scarce migrants".The remaining species are those which the BBRC assesses