Sufficiency of Horseshoe Crab Eggs for Red Knots During Spring Migration Stopover in Delaware Bay USA
Horseshoe crab (Limulus polyphemus) eggs are a dietary staple of the red knot (Calidris canutus) during its spring stopover on the Delaware Bay. Numbers of knots stopping in Delaware Bay declined in the 1990s concurrent with a decline in horseshoe crabs, leading to the hypothesis that reduced horses...
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The Wildlife Society
2011
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ftbioone:10.1002/jwmg.129 2023-07-30T04:02:12+02:00 Sufficiency of Horseshoe Crab Eggs for Red Knots During Spring Migration Stopover in Delaware Bay USA Sarah M. Karpanty Jonathan Cohen James D. Fraser Jim Berkson Sarah M. Karpanty Jonathan Cohen James D. Fraser Jim Berkson world 2011-06-01 text/HTML https://doi.org/10.1002/jwmg.129 en eng The Wildlife Society doi:10.1002/jwmg.129 All rights reserved. https://doi.org/10.1002/jwmg.129 Text 2011 ftbioone https://doi.org/10.1002/jwmg.129 2023-07-09T08:15:12Z Horseshoe crab (Limulus polyphemus) eggs are a dietary staple of the red knot (Calidris canutus) during its spring stopover on the Delaware Bay. Numbers of knots stopping in Delaware Bay declined in the 1990s concurrent with a decline in horseshoe crabs, leading to the hypothesis that reduced horseshoe crab egg abundance limited the red knot population. Management efforts, including a seasonal harvest moratorium in the Delaware Bay, have been instituted to restore crab populations to levels of sustainable use by multiple users, including migratory birds. Our objective was to evaluate the sufficiency of horseshoe crab eggs in Delaware Bay in May–June 2004 and 2005 for knots to refuel for their migratory flight to the Arctic breeding grounds. We examined egg counts to determine if there were fewer high egg-density sites later than earlier in the day and season, as migrating birds might deplete this resource. We studied foraging rates at red knot locations to determine if foraging probes increased with time of day and season as birds depleted surface eggs by pecking, then began probing for subsurface eggs. Finally, we experimentally tested whether red knots and their competitors depleted horseshoe crab eggs. Crab egg numbers at knot foraging sites did not decline throughout the day or season in 2004. In both years, we found no evidence that knots switched from pecking to probing with increases in time since sunrise or start of the stopover. Egg numbers were similar in exclosed and accessible plots on crab nesting depressions and in areas of open intertidal zone, but were significantly lower in accessible than in exclosed plots in the wrack line. Our results indicate that horseshoe crab eggs in Delaware Bay were sufficient to support the refueling of the present-day stopover population of red knots. If an increase in the availability of crab eggs to foraging birds does not result in an increase in knot numbers, managers must prioritize mitigation of limiting factors at other historically important spring stopovers ... Text Arctic Calidris canutus Red Knot BioOne Online Journals Arctic The Journal of Wildlife Management 75 5 984 994 |
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description |
Horseshoe crab (Limulus polyphemus) eggs are a dietary staple of the red knot (Calidris canutus) during its spring stopover on the Delaware Bay. Numbers of knots stopping in Delaware Bay declined in the 1990s concurrent with a decline in horseshoe crabs, leading to the hypothesis that reduced horseshoe crab egg abundance limited the red knot population. Management efforts, including a seasonal harvest moratorium in the Delaware Bay, have been instituted to restore crab populations to levels of sustainable use by multiple users, including migratory birds. Our objective was to evaluate the sufficiency of horseshoe crab eggs in Delaware Bay in May–June 2004 and 2005 for knots to refuel for their migratory flight to the Arctic breeding grounds. We examined egg counts to determine if there were fewer high egg-density sites later than earlier in the day and season, as migrating birds might deplete this resource. We studied foraging rates at red knot locations to determine if foraging probes increased with time of day and season as birds depleted surface eggs by pecking, then began probing for subsurface eggs. Finally, we experimentally tested whether red knots and their competitors depleted horseshoe crab eggs. Crab egg numbers at knot foraging sites did not decline throughout the day or season in 2004. In both years, we found no evidence that knots switched from pecking to probing with increases in time since sunrise or start of the stopover. Egg numbers were similar in exclosed and accessible plots on crab nesting depressions and in areas of open intertidal zone, but were significantly lower in accessible than in exclosed plots in the wrack line. Our results indicate that horseshoe crab eggs in Delaware Bay were sufficient to support the refueling of the present-day stopover population of red knots. If an increase in the availability of crab eggs to foraging birds does not result in an increase in knot numbers, managers must prioritize mitigation of limiting factors at other historically important spring stopovers ... |
author2 |
Sarah M. Karpanty Jonathan Cohen James D. Fraser Jim Berkson |
format |
Text |
author |
Sarah M. Karpanty Jonathan Cohen James D. Fraser Jim Berkson |
spellingShingle |
Sarah M. Karpanty Jonathan Cohen James D. Fraser Jim Berkson Sufficiency of Horseshoe Crab Eggs for Red Knots During Spring Migration Stopover in Delaware Bay USA |
author_facet |
Sarah M. Karpanty Jonathan Cohen James D. Fraser Jim Berkson |
author_sort |
Sarah M. Karpanty |
title |
Sufficiency of Horseshoe Crab Eggs for Red Knots During Spring Migration Stopover in Delaware Bay USA |
title_short |
Sufficiency of Horseshoe Crab Eggs for Red Knots During Spring Migration Stopover in Delaware Bay USA |
title_full |
Sufficiency of Horseshoe Crab Eggs for Red Knots During Spring Migration Stopover in Delaware Bay USA |
title_fullStr |
Sufficiency of Horseshoe Crab Eggs for Red Knots During Spring Migration Stopover in Delaware Bay USA |
title_full_unstemmed |
Sufficiency of Horseshoe Crab Eggs for Red Knots During Spring Migration Stopover in Delaware Bay USA |
title_sort |
sufficiency of horseshoe crab eggs for red knots during spring migration stopover in delaware bay usa |
publisher |
The Wildlife Society |
publishDate |
2011 |
url |
https://doi.org/10.1002/jwmg.129 |
op_coverage |
world |
geographic |
Arctic |
geographic_facet |
Arctic |
genre |
Arctic Calidris canutus Red Knot |
genre_facet |
Arctic Calidris canutus Red Knot |
op_source |
https://doi.org/10.1002/jwmg.129 |
op_relation |
doi:10.1002/jwmg.129 |
op_rights |
All rights reserved. |
op_doi |
https://doi.org/10.1002/jwmg.129 |
container_title |
The Journal of Wildlife Management |
container_volume |
75 |
container_issue |
5 |
container_start_page |
984 |
op_container_end_page |
994 |
_version_ |
1772812931457613824 |