The Decline of the Red Knot Lawrence Niles Ph.D Amanda Dey Ph.D NJ Division of Fish and Wildlife, US Humphrey Sitters Ph.D International Wader Study Group, UK Clive Minton Ph.D Victoria Wader Study Group, Aus. The red knot makes one of the longest Breeding Area migrations of any bird Breeding Area Northbound Flight Breeding Area Stopover Wintering Area Wintering Area Wintering Area South Bound Flight The Delaware Bay is one of four major shorebird stopovers in the world Shorebirds on the Delaware Bay gain up to 10% of bodyweight/day Until 1992, the harvest of horseshoe crabs was a tradition harvest to supply bait for a small eel fishery By 1996 millions of crabs were being killed to supply bait for a coast-wide conch fishery Recent Horseshoe Crab Landings (NMFS) 7000000 6500000 VA MD 6000000 DE NJ 5500000 NY 5000000 4500000 4000000 3500000 Pounds 3000000 2500000 2000000 1500000 1000000 500000 0 1990 1991 1992 1993 1994 1995 1996 1997 1998 1999 2000 Year In 1998 the ASMFC created management plan for horseshoe crabs that froze harvest at 25% of peak harvest without any understanding of population size or recruitment The only data available, a baywide trawl, . was dismissed although it documented a 90% drop in stock DE DFW 30-foot Trawl Survey - Horseshoe Crab Index Horseshoe Crabs, catch/unit effort 14 CPUE Total HS Crabs 12 10 8 6 4 Geo. mean Horseshoe Crabs 2 0 1990 1992 1994 1996 1998 2000 2002 2004 N = 350 Year Egg densities on bay beaches fell from average counts of 40,000 egg/m in the early 1990’s to 4000 eggs/m in 2000 Mean Egg Density 2000-2005 6000 5000 4000 3000 2000 1000 Egg density eggs/m Egg density 0 2000 2001 2002 2003 2004 2005 Year The number of red knots reaching weights >=185g fell dramatically between 1997-2003 40000 35000 33741 30000 25000 20509 19922 20000 17340 15000 12075 10000 5376 5000 813 0 1997 1998 1999 2000 2001 2002 2003 The Delaware Bay stopover population has been declining since 1997. Peak numbers of red knots of over 100,000 in the 1980’s have fallen to 13,315 in 2004 Red Knot Surveys 1997-2004 60000 50000 40000 30000 20000 10000 number of birds number 0 0 5 10 15 20 25 30 35 40 Daynum 1997 1998 1999 2000 2001 2002 2003 2004 We expanded our study to the primary South Breeding AreaAmerican wintering areas Breeding Area in 2000 Northbound Flight Breeding Area Stopover Wintering Area Wintering Area Wintering Area South Bound Flight We compared populations of the red knot and hudsonian godwit, an arctic breeder that does not stopover on the Delaware Bay . Red knot numbers declined 68% in the period of our study 1982/86 Species Region Atlas 2000 2002 2003 2004 2005 Red Knot Tierra del Fuego 53232 51255 27242 29915 30778 17653 Godwit Tierra del Fuego 31132 31090 46088 42470 66840 53725 Numbers fell dramatically this year We expanded our study to the primary breeding Breeding Area area in 1999 Breeding Area Northbound Flight Breeding Area Stopover Wintering Area Wintering Area Wintering Area South Bound Flight The red knot was compared to the golden plover, a long distant migrant that does not stopover on the Delaware Bay Between 2000 and 2004 nest densities fell from 1.2 nest/km to .5 nest/km Table 2. Breeding density of red knot and American Golden Plover on Southampton Island study site, Nunavut, Canada, 2000 through 2004. Breeding # Nests on Density Year Species Study Site (Nests/sq. km) 2000 Red Knot 11 1.155 2001* Red Knot 7 0.765 2002 Red Knot 9 0.984 2003 Red Knot 3 0.328 2004 Red Knot 5 0.547 2001 Am. Golden Plover 7 0.765 2002 Am. Golden Plover 5 0.547 2003 Am. Golden Plover 10 1.093 2004 Am. Golden Plover 9 0.984 * 2001 - early hatching year, seven knots with broods found on study site We expanded our study to the east coast in 2004 East Coast Red Knot Resightings May 22 - 28, 2004 Maisonnette, New Brunswick, Canada ( 3 ) May 12; ( 8 ) Ma y 24, 2004 Ontario Quebec New Brunswick Maine Nova Scotia Vermont New Hampshire New York Michigan Massachusetts ConnecticutRhode Island Pennsylvania Long Island, NY ( 12 ) May 27, 2004 Ohi o New Jersey Maryland Delaware West Virginia District of Columbia Chincoteague NWR, VA ( 3 ) May 25, 2004 Kentucky Virginia - Tennessee Pea Isla nd NWR ( 10 ) & ( 3 ) May 25; ( 2 ) May 27, 2004 North Carolina Cape Hatteras, NC ( 4 ) May 24, 2004 Ocracoke Island, NC ( 32 scattered ) May 27; ( >200 ) May 28, 2004 Cape Lookout, NC ( 115 ) May 27, 2004 South Carolina Georgia Turtle Island, GA ( 270 ) May 27, 2004 Legend Cumberland Isla nd, GA ( 0 ) May 27, 2004 U.S.A. Fort Georg e Inlet, FL ( 33 ), ( 127 ), ( 21 ), & ( 133 ) May 27, 2004 Canada Under 100 101 - 500 Florida 501 - 1000 Over 1000 Scale 1:11,667,279 095 190 380 570 760 Ki lometers The differences in population counts in Tierra del Fuego and Delaware Bay indicates the knots that bypassed the bay in 2003 and 2004 died in 2005 year 2000 2002 2003 2004 2005 Tierra del 51255 27242 29915 30778 17653 Fuego Delaware 43145 31695 16025 13315 15300 Bay The decline of the red knot represents a general decline and threat of all species that stopover on the bay Peak counts of Red Knot, Ruddy Turnstone & Sanderling, Delaware Bay 2000 - 2004 100,000 90,000 80,000 70,000 60,000 Red Knot 50,000 Ruddy Turnstone 40,000 Sanderling Number of Birds 30,000 20,000 10,000 0 2000 2001 2002 2003 2004 Year Birds must now move about the bay in search of any significant source of eggs Why An emergency? • Sudden decline in 2003 without corresponding declines in Tierra del Fuego suggest birds are now by passing the bay • The subsequent failure to breed and poor mortality caused a 40% decline in Tierra del Fuego in 2005 • As yet unreleased data on the ocean trawl for crabs point to continuing declines in the horeshoe crab population despite 50% reductions in harvest..