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 SPP	6-May	14-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 SPP	6-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