Date: Wed, 22 May 2002 11:26:56 -0400 Reply-To: Maryland Birds & Birding Sender: Maryland Birds & Birding From: Henry Armistead <74077.3176@COMPUSERVE.COM> Subject: part 1, Dorchester May count analysis MIME-Version: 1.0 Content-Transfer-Encoding: 7bit Content-Type: text/plain; charset=us-ascii Content-Disposition: inline Part 1 (of 5 parts). Species abundance changes, 1966-2002, on 70 May counts in Dorchester County. 60 species. 4,610 words. Here is an informal analysis of changes reflected by the 70 counts. Counts have been done on the first May Saturday since 1966 (except for 1966 which was the first Friday) and the second May Saturday since 1970. There are only spreadsheets for the 1966-1976 counts. All the other data are in files and will eventually be entered into one spreadsheet and summarized for a suitable article in "Maryland Birdlife" (assuming that periodical gets back on track). Right now I am simply comparing the "old days" with the past few years results, and pardon the use of an obsolete phylogenetic order. It is remarkable that a minimum of 60 species, about one quarter of all seen, perhaps a third of the more abundant ones, show dramatic changes in abundance. In most cases I do not know why. I am hoping some of the MDOSPREY readers can offer reasons for some of these often dramatic changes. Please speak up! And please keep in mind that most of these counts are approximate. The route followed is consistent, one of about 180 miles done by one party usually of 1-4 persons. Elliott Island Rd. midnight to 3 or 4 A.M. Henry's Crossroads to Transquaking River and Blackwater N.W.R. c. 3:30 A.M. - 5 A.M. Blackwater 5 A.M. - 1 P.M. Hooper's Island 2:30-4:00 P.M. Elliott Island 5 P.M. - 8:30 or 9:00 P.M. In the early years from c. 1966 - early 1970's I also included northeast parts of the county where breeding Yellow-throated Vireos, redstarts, and rough-winged swallows helped build the list and where there was also better warblering. In those years I also made more stops but of shorter duration. On one day, for example, 288 stops were made, perhaps 100 more than what is done now. Other variables include my loss of hearing of high frequency bird sound starting c. 15 years ago and growing worse. This is partially compensated for by often having companions whose hearing is good, although I am still sometimes alone on these counts. In addition the cumulating knowledge of where and when birds occur help to keep the list and numbers up. In the face of adverse weather the counts did not always begin at midnight, although most have. In such cases obviously the numbers of marsh birds, owls, and nightjars were lower. To be sure there are variables such as these, and the weather, that ensure that these numbers should be regarded as at best approximations in most cases. Nevertheless certain changes seem obvious. For another variable see below under American Oystercatcher. Abbreviations: BNWR, Blackwater National Wildlife Refuge; CBC's, Christmas Bird Counts; EIR, Elliott Island Rd.; NABBS, North American Breeding Bird Survey; SAV, Submerged Aquatic Vegetation; SDC, southern Dorchester County. Here goes. One can only draw so many conclusions from one place but seen in the context of, say, CBC's and NABBS's for the entire state, some of these trends are probably validly reflected even in such a local context. Here is a typical species account with explanations: Double-crested Cormorant. 17/18 (seen on 17 of 18 counts 1966-1976) average 17 (averaging 17 per each count in those years, rounded off to nearest whole number). Recently (that means last 5 years or so; so does "now") has increased dramatically, first bred in MD nearby at Poplar Island and has bred in SDC recently on Barren and Spring Islands. Even without the presence of these breeding colonies numbers seen now usually average way over 17 and are sometimes 200 or 300+. Horned Grebe. 6/18. Now practically never seen in May. Sustained a huge population decrease during the 1980's and has not recovered. In 1971, a remarkably late spring, an unbelievable 47 were seen on May 1 along with other huge numbers of lingerers: 21 Common Loons, 91 Green-winged Teal, 1375 Lesser Scaup, 83 White-winged Scoters, 10 Common Snipe, 108 Myrtle Warblers, 8 Rusty Blackbirds, 106 Savannah Sparrows, 3 Slate-colored Juncos, and 415 White-throated Sparrows. Some of these would be good numbers for a CBC party total and most (perhaps all) have not been equalled since. Brown Pelican. 0/18. For the past several years now seen every time with totals of 205 and 325 in 2002. Circa 150 pairs have nested in SDC on Spring Island for the past 2 years and hundreds were present on s. Barren I. last year, constructing nest platforms but not following through; both islands are sections of BNWR. On June 1, 2000, Marshall Iliff and I estimated over 1,000 in the Spring Island area, following rapidly on the heels of the county's first record, 4 imm. seen at Bloodsworth I. on July 4, 1992, by George Armistead and myself. Fairly easily seen from the "mainland" from Hooper's I. and less so, from the lower EIR. Green Heron. 18/18. Average 16. Now only a few are seen each day and it has even been missed. There used to be a small evening flight towards Elliott Island village in May. With the great die-out of SAV in the early 1970's, the consequent drastic decline of many waterfowl, and therefore the lack of the use of (or the building of ) duck blinds, these little herons have suffered. They LOVE to nest on blinds. Cattle Egret. 16/18. Average 43. They have declined in most of the Middle Atlantic. Very few nest on SDC islands now. I miss them on the count sometimes. The area around the landfill near Golden Hill and BNWR are the best places to look for them. Best to all.-Harry Armistead, 523 E. Durham St., Philadelphia, PA 19119-1225. 215-248-4120. Any off-list replies, please, to: harryarmistead@hotmail.com. ======================================================================= To leave the MDOsprey list, send e-mail to listserv@home.ease.lsoft.com with the following message in line 1: signoff mdosprey ======================================================================= =========================================================================