With a particular interest in the Holarctic avifauna, I long regretted the absence of an up-to-date checklist of bird species regularly occurring in the Palaearctic and Nearctic regions. I sought an easily referenced record of recent and potential taxonomic changes, also taking into account improvements in distributional knowledge (particularly in Mexico and Himalaya). Consequently over several years I developed and maintained a working checklist as the core of my personal records database. I have posted it on this website in the hope that it may be a useful resource for other birders with similar interests.
The checklists maintained by regional and national recording authorities are (necessarily) rigorous and conservative. My approach has been more liberal - implementing all splits adopted by at least one relevant authority (but with clear indication of the recognising authorities), and identifying potential splits even where questionable.