Friday, June 6, 2008

DelBay Shorebird Numbers

Kathy Clark of the NJ Endangered and Nongame Species Program shared the following data from the weekly aerial surveys of Delaware Bay shorebirds, which are conducted every Tuesday. Red Knot peak numbers were similar to last year's. Unfortunately, the word on the street is that horseshoe crab egg densities have been low, and knot weight gain was slow. Kathy noted that the change in overall shorebird numbers between May 28 and June 3 was smaller than one would expect, possibly reflecting slower weight gain and the need to stay longer on the Bay in order to "make weight. " One would have thought many of the May 28 birds would have departed by June 3.

Knots and the other shorebirds using the crab eggs need to "make weight" before they depart, accumulating enough fat reserves to fly to the Arctic with enough fat left over to initiate nesting. The threshold departure weight for Red Knot is 180 grams; some knots arrive on the Bay weighing less than half that after their flight from northern Brazil.

Very much worth the read is the exhaustive 2007 US Fish and Wildlife Service Document, The Status of the Red Knot in the Western Hemisphere, which can be downloaded from the ENSP Delaware Bay Shorebird web site.

Abbreviations:
REKN=Red Knot
RUTU=Ruddy Turnstone
SESA=Semipalmated Sandpiper
SAND=Sanderling
PEEP=unidentified small Calidris sandpipers
DOW=dowitcher, nearly all Short-billed
DUNL=Dunlin


2008 Aerial Survey of Delaware Bay Shorebirds, by NJ and DE Fish and Wildlife agencies














































































































































































































































































NJ SHORE SPP6-May14-May 21-May 28-May 3-Jun 10-Jun Total by Species
REKN 50 3,245 10,045 9,370 2,040
24,750
RUTU 60 2,845 9,020 9,835 9,850
31,610
SESA 0 18,100 23,490 28,395 25,425
95,410
SAND 1,671 4,755 11,925 8,815 6,405
33,571
PEEP 1,145 275 50 0 0
1,470
DOW 865 2,100 550 270 50
3,835
DUNL 12,850 26,145 8,270 7,840 0
55,105
SUBTOTAL 16,641 57,465 63,350 64,525 43,770
245,751
DE SHORE SPP6-May 14-May 21-May 28-May 3-Jun 10-Jun Total by Species
REKN 0 2,985 5,350 5,320 3,750
17,405
RUTU 0 2,320 1,320 11,465 6,760
21,865
SESA 0 15,690 19,750 24,930 33,840
94,210
SAND 60 215 1,490 4,415 2,930
9,110
PEEP 90 70 0 0 20
180
DOW 8,695 25,545 7,630 4,420 0
46,290
DUNL 295 2,420 10 50 0
2,775
SUBTOTAL 9,140 49,245 35,550 50,600 47,300
191,835
TOTAL-BAY SPP
6-May
14-May 21-May 28-May 3-Jun 10-Jun Total by Species
REKN 50 6,230 15,395 14,690 5,790
42,155
RUTU 60 5,165 10,340 21,300 16,610
53,475
SESA 0 33,790 43,240 53,325 59,265
189,620
SAND 1,731 4,970 13,415 13,230 9,335
42,681
PEEP 1,235 345 50 0 20
1,650
DOW 1,160 4,520 560 320 50
6,610
DUNL 21,545 51,690 15,900 12,260 0
101,395
TOTAL 25,781 106,710 98,900 115,125 91,070
437,586

Surveys conducted by K. Clark and R. Porter


May 21 -- Incomplete count. Plane was prohibited from entering Dover Airspace

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