The looming split of Calonectris diomedea poses some record-keeping challenges for Long Island birders. The split means that all past records Cory's that were not identified to subspecies will be reassigned as Cory's/Scopoli's, and we are being encouraged to report future records in the same way, unless they can be conclusively identified.
The split seems pretty dubious to me. The taxa diomedea (which will be called Scopoli's, after "the Linnaeaus of the Austrian Empire"--at least for now!) and borealis (which will continue to be called Cory's....) are extremely similar in every way and don't appear to show any consistent differences in status or occurrence in our region, except that borealis is significantly more numerous. Because they are difficult to distinguish in the field, historical records of diomedea from our region have always been fortuitous—based on specimens and photographs identified ex post facto. When people started trying to identify them in the field, for instance showing me back of the camera photos of birds we had just observed together, my reply was, "If that's what diomedea looks like, I've been seeing it all my life." But the very fact that a non-trivial percentage of specimens and interpretable photos have turned out to be diomedea proves that it is not truly rare here. The question now is whether it is actually numerous enough to justify the "conservative" position that all birds that are not critically identified ought to be reported as slashes. I'm not sure yet whether this is the right approach, so I will express a few consideratons here. The proportion of Calonectris in our area that can be critically identified is quite small, probably fewer than one in twenty. Curiously, this is possibly roughly similar to the (unknown) ratio of diomedea to borealis as well. This means that the conservative position will result in a very significant underestimation of the abundance of both taxa in almost all contexts, but most significantly in the case of borealis, which we know is an abundant taxon, but which will appear at least an order of magnitude less numerous than it really is. Diomedea will appear rarer than it really is, but that's less of an issue because it is at least uncommon and not one of our most abundant seabirds, unlike borealis. Another issue is that the frequency of identifiable encounters will be significantly lower from shore, where most of the total records originate) than at sea. This is because shore-based observations are never at extremely close range, whereas such observations occur regularly at sea (though still far fewer than distant detections). This is a problem because one of the most important questions is whether there might be difference between the two taxa in terms of inshore/offshore occurrence. Whatever the reality, it will be easier to document and record Scopoli's offshore. My hope is that near-shore boat trips, such as to Cox's Ledge and from Montauk whale watching trips, will help to set baselines for the various parameters. A final point of personal interest concerns seasonal status. Since I began studying these birds in nearby Rhode Island in the early 1980s, Calonectris have been occurring earlier and in larger numbers during late May and through June (Conway (1979) doesn't show them becoming common until July). It is not necessarily to be assumed that this change in seasonal status involves the two taxa in equal degree. It might be best to try the "conservative" approach for a couple of years, in order to compile robust samples of proven borealis, as well as of diomedea. Then, if the proportions of diomedea among critically identified birds is proven to be small in all contexts, as expected, we might revert to calling everything borealis unless proven/suspected otherwise, thus rendering the actual abundance of borealis more accurately. Shai Mitra Bay Shore -- (copy & paste any URL below, then modify any text "_DOT_" to a period ".") NYSbirds-L List Info: NortheastBirding_DOT_com/NYSbirdsWELCOME_DOT_htm NortheastBirding_DOT_com/NYSbirdsRULES_DOT_htm NortheastBirding_DOT_com/NYSbirdsSubscribeConfigurationLeave_DOT_htm ARCHIVES: 1) mail-archive_DOT_com/nysbirds-l@cornell_DOT_edu/maillist_DOT_html 2) surfbirds_DOT_com/birdingmail/Group/NYSBirds-L 3) birding_DOT_aba_DOT_org/maillist/NY01 Please submit your observations to eBird: ebird_DOT_org/content/ebird/ --
