When creating an eBird checklist one has the option of selecting a species, subspecies or sometimes a subspecies group. I've noticed an uptick recently in the number of observers in coastal New York using the latter two options, in the belief perhaps that this improves the scientific value of their checklist or to guard against future taxonomic upgrades that would promote subspecies to full species status.
Unfortunately very few checklists provide any justification for subspecies designations and I suspect the majority are simply guesses based on range or other assumptions. While these choices may well be correct, I don't think this is good practice because it implies a greater level of observation than actually occurred. Importantly subspecies selections may actually be wrong, which could confuse future analyses. A timely example is the CATTLE EGRET that's lingering in mid-town Manhattan. I noticed several recent checklists entering this bird as 'Cattle Egret (Eastern) (Bubulcus ibis coromandus)'. THIS IS NOT CORRECT. Other observers have entered the sighting at the species level only 'Cattle Egret (Bubulcus ibis)' or as 'Cattle Egret (Western) (Bubulcus ibis ibis)'. In this case, these are both correct. That said, I don't think I've seen a single checklist using Western Cattle Egret that actually comments on how this selection was made. So why is Western Cattle Egret correct? Cattle Egret has a broad distribution across the temperate and tropical zones of both the Old and New Worlds. The Americas were colonized in the 1950s by birds that crossed the Atlantic from Africa, and are thus Western Cattle Egret (B. ibis ibis). The name reflects the fact that these are from the western half of the pre-expansion range (i.e. southern Europe, the Middle East and Africa). The range of Eastern Cattle Egret (B. ibis coromandus) extends from central Asia eastward through India to Japan and now includes Australia and New Zealand following a similarly rapid range expansion in the opposite direction. Why both subspecies underwent massive range expansions at about the same time is fascinating topic in itself. To my knowledge there is no evidence that Eastern Cattle Egret has occurred in the eastern US and Canada (or I suspect, anywhere in the Americas except perhaps as vagrants to western Alaska or Hawaii). This is important because some authorities already treat Eastern and Western Cattle Egrets as separate species and makes the point that labels should be used carefully and if possible chosen on the basis of direct observation rather than assumptions from a pull-down menu. In the case of the Manhattan egret I think we can safely call this individual a Western Cattle Egret because of the limited extent of the pale orange feathering on the breast, head, neck and center of the back. This coloring is usually more extensive and often a darker orange in Eastern Cattle Egrets of similar age. The taxa also differ in their proportions, especially leg and bill length, but this would be hard to assess on a lone bird without good photos. Bill, leg and iris color are too variable to be much use. There are rumors that vocalizations may also be diagnostic but when was last time you heard a Cattle Egret calling away from a nesting colony? In summary, I recommend entering sightings into eBird at subspecies level with caution, ideally providing a note on why you did so. Plenty of birds can be identified at this level and this is a great way to hone your observation skills and expand your knowledge of bird distribution. It's true that for many common birds blanket assumptions are reasonable, at least in the northeast. For example in New York State, Northern Flickers are almost invariably Yellow-shafted (Colaptes auratus auratus), and likewise Northern Orioles are almost always Baltimore Orioles (Icterus galbula). These assumptions would not necessarily hold if you were birding closer to the Rockies where the western counterparts are more frequent and broad zones of overlap give rise to frequent integrades. Identifying birds at the subspecies levels adds a thrilling dimension to birding but can be tricky and less clear cut than species identifications. It's great that eBird offers this as an option because it should improve our knowledge of subspecies ranges, but for the reasons discussed above, these choices should be used with care. Here are a couple of useful links from eBird expanding on this thought provoking topic. http://help.ebird.org/customer/portal/articles/1010552-understanding- subspecies-in-ebird http://help.ebird.org/customer/portal/articles/1006768-entering-non-species- taxa?b_id=1928 -- Angus Wilson New York City & The Springs, NY, USA -- NYSbirds-L List Info: http://www.NortheastBirding.com/NYSbirdsWELCOME.htm http://www.NortheastBirding.com/NYSbirdsRULES.htm http://www.NortheastBirding.com/NYSbirdsSubscribeConfigurationLeave.htm ARCHIVES: 1) http://www.mail-archive.com/nysbirds-l@cornell.edu/maillist.html 2) http://www.surfbirds.com/birdingmail/Group/NYSBirds-L 3) http://birding.aba.org/maillist/NY01 Please submit your observations to eBird: http://ebird.org/content/ebird/ --
