Date: Sun, 28 Apr 2002 12:24:36 -0400 Reply-To: Maryland Birds & Birding Sender: Maryland Birds & Birding From: "Frederick W. Fallon" Subject: some nocturnal records; a leap-year artifact MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Transfer-Encoding: 7bit Last night (Saturday) a slightly drizzly Patuxent Bird Club field trip to Wooton's Landing heard these species : Barred Owl, duelling Whip-poor-wills, sev. Woodcock in flight dispaly, and a King Rail calling from the fresh-water marsh. Two days earlier, the same birds had announced themselves along with a Marsh Wren - rather far up the river. Many Yellow-throats and some Swamp Sparrows also continued calling well after dark. The same morning (27th) our "yard" Baltimore Oriole returned, very close to his mean arrival date. The Catbird, which had put in a brief appearance one week ago, returned and apparently decided to take up residence here after all - also very near his 23-year mean arrival date. BTW, in computing the consistency of arrival dates, I wonder if the effect of leap year is usually accounted for - a bird which arrives as nearly as he can to an exactly one-year (365.25 day) period would arrive on (say) March 1 of a leap year, then Mar 1 again, then again Mar 1, then Mar 2, then Mar 1 the next leap year. So a measure of the dispersion of arrival times should take this mix of calendar dates into account (as astronomers do by using serially-numbered "Julian Dates"). To be sure the effect is a small one, but systematic. Fred Fallon Bowie fwfallon@earthlink.net ======================================================================= To leave the MDOsprey list, send e-mail to listserv@home.ease.lsoft.com with the following message in line 1: signoff mdosprey ======================================================================= =========================================================================