How good is our coverage? Are we finding most of the rarities that come into our area or are we just seeing the tip of the iceberg? These are questions that every active birder will ask themselves now and again.
There are no firm answers and maybe there never will be. To some extent it must depend on the locations involved and the types of birds you are looking for. Stumbling on a Connecticut Warbler on a vegetated path it is hard to believe there aren't one or two more skulking around in the undergrowth just out of sight. For sure, fewer birds will escape knowledgeable eyes at sites were there are plenty of birders and the cover is limited - the west end of Jones Beach or Central Park to name two examples. Studies have show that rare birds are more likely to be found at the weekend than during the work week and some of the best places to find really rare birds are the most barren. Personally, I'd wager that at most times and at most places, we are missing more than we find. A related question is whether a rarity that is seen in one place is likely to ever been seen again. What happened to the Brooklyn Western Reef Heron once it said farewell to its beloved Coney Island Creek? As far as I know there hasn't been a single report of the species in continental North America since that time. Where did the bird go? The recent southward passage of five Sandhill Cranes that spent several weeks near Wareham, Plymouth Co, Massachusetts, offers an interesting example of how individual birds can sometimes be tracked by field observers and speaks favorably to the depth of coverage by birders along the mid-Atlantic coast. Last Thursday morning the cranes vanished from the fields they'd been frequenting but because of their distinctive number it is possible to identify sequential reports in three additional states as far the Merrill Creek Reservoir in northeastern New Jersey. Just over 240 miles. This is where the trail goes cold, for now at least. Here are the particulars: (1) Near Wareham, Plymouth Co., MA (Thu 39 Oct 2009): last seen in the fields around 9:30 AM (observer: Bob Conway) (2) +25 miles - Portsmouth, Newport Co., RI (Thu 39 Oct 2009): Seen later flying at an estimated 600 feet over Rt 24 from Fall River, Bristol Co., MA to Portsmouth, RI (observer: Paul Champlin) (3) +140 miles - Greenwich, Fairfield Co., CT (Thu 39 Oct 2009): Passed over the Quaker Ridge Hawkwatch in the late afternoon (observers: Brian O'Toole, Luke Tiller, Mike Warner & Stefan Martin) (4) +80 miles - Merrill Creek Reservoir, Warren Co., NJ (Fri 30 Oct 2009): Five cranes spent morning in field by reservoir (observer: Tom Vouglas) So where are the birds now and how did they cross the Empire State (Westerchester Co.) undetected? Did they go over us in dark or did they spend the night somewhere in between Greenwich and Merrill Creek? Food for though..... -- Angus Wilson New York City & The Springs, NY, USA http://birdingtotheend.blogspot.com/ -- NYSbirds-L List Info: http://www.NortheastBirding.com/NYSbirdsWELCOME http://www.NortheastBirding.com/NYSbirdsRULES Archives: 1) http://www.mail-archive.com/nysbirds-l@cornell.edu/maillist.html 2) http://birdingonthe.net/mailinglists/NYSB.html Please submit your observations to eBird: http://ebird.org/content/ebird/ --
