Shorebird Predation on Eggs of Horseshoe Crabs during Spring Stopover on Delaware Bay

The Auk ◽  
1993 ◽  
Vol 110 (4) ◽  
pp. 927-930 ◽  
Author(s):  
Gonzalo Castro ◽  
J. P. Myers
Keyword(s):  
Delaware Bay ◽  
Horseshoe Crabs ◽  
Spring Stopover

Effect of forager density on feeding rates in spring-staging Semipalmated Sandpipers (Calidris pusilla) using different foraging modes

2018 ◽  
Vol 96 (9) ◽  
pp. 996-1001 ◽  
Author(s):  
Ivana Novcic ◽  
Guy Beauchamp
Keyword(s):  
Delaware Bay ◽  
Nearest Neighbour ◽  
Feeding Rates ◽  
Stopover Site ◽  
Neighbour Distance ◽  
Short Intervals ◽  
Foraging Modes ◽  
Calidris Pusilla ◽  
Spring Stopover ◽  
Semipalmated Sandpipers

We examined the influence of the density of foragers on feeding rates of Semipalmated Sandpipers (Calidris pusilla (Linnaeus, 1766)) while using different foraging modes at a spring stopover site in Delaware Bay, USA. Using dynamic estimates of interindividual distances obtained at short intervals of time, we explored how forager density affected feeding rates when Semipalmated Sandpipers used visual pecking or tactile probing. Pecking rate significantly increased with interindividual distances, whereas probe rate was not affected by density. Our study also showed that in fast-moving foragers, such as Semipalmated Sandpipers, in which the number of nearby foragers and distance to the nearest neighbour continuously change throughout the foraging bout, pecking rates are more affected by nearest neighbour distance than by the number of foragers in their immediate vicinity. In addition, our study implies that foragers using different foraging modes might be differently affected by nearby competitors perhaps in response to prey disturbance by neighbours.

scholarly journals Coincident ruddy turnstone migration and horseshoe crab spawning creates an ecological ‘hot spot’ for influenza viruses

2010 ◽  
Vol 277 (1699) ◽  
pp. 3373-3379 ◽  
Author(s):  
Scott Krauss ◽  
David E. Stallknecht ◽  
Nicholas J. Negovetich ◽  
Lawrence J. Niles ◽  
Richard J. Webby ◽  
...  
Keyword(s):  
Horseshoe Crab ◽  
Hot Spot ◽  
Sampling Site ◽  
High Tide ◽  
Delaware Bay ◽  
Influenza Viruses ◽  
Virus Surveillance ◽  
Large Numbers ◽  
Horseshoe Crabs ◽  
Migrating Birds

Since 1985, avian influenza virus surveillance has been conducted annually from mid-May to early June in charadriiform species from the families Scolopacidae and Laridae (shorebirds and gulls) at Delaware Bay in the northeast United States. The mass migrations of shorebirds, gulls and horseshoe crabs ( Limulus polyphemus ) coincide at that time, and large numbers of migrating birds pause at Delaware Bay to feed on horseshoe crab eggs deposited at the high-tide line. Influenza viruses are consistently isolated from charadriiform birds at Delaware Bay, at an overall rate approximately 17 times the combined rate of isolation at all other surveillance sites worldwide (490 isolates/9474 samples, 5.2% versus 49 isolates per 15 848 samples, 0.3%, respectively; Proportion test, p < 0.0001). The likelihood of isolating influenza viruses at Delaware Bay is dependent on the presence of ruddy turnstone ( Arenaria interpres ) at the sampling site ( G -test of independence, p < 0.001). The convergence of host factors and environmental factors results in a unique ecological ‘hot spot’ for influenza viruses in Charadriiformes .

scholarly journals Age and sex specific timing, frequency, and spatial distribution of horseshoe crab spawning in Delaware Bay: Insights from a large-scale radio telemetry array

2010 ◽  
Vol 56 (5) ◽  
pp. 563-574 ◽  
Author(s):  
David R. Smith ◽  
Brousseau Lorne J. ◽  
Mary T. Mandt ◽  
Michael J. Millard
Keyword(s):  
Water Temperature ◽  
Large Scale ◽  
Horseshoe Crab ◽  
Radio Telemetry ◽  
Spring Tide ◽  
Delaware Bay ◽  
Spawning Season ◽  
Adult Age ◽  
Horseshoe Crabs ◽  
Males And Females

Abstract To study horseshoe crab Limulus polyphemus spawning behavior and migration over a large-spatial extent (>100 km), we arrayed fixed station radio receivers throughout Delaware Bay and deployed radio transmitters and archival tags on adult horseshoe crabs prior to their spawning season. We tagged and released 160 females and 60 males in 2004 and 217 females in 2005. The array covered approximately 140 km of shoreline. Recapture rates were >70% with multi-year recaptures. We categorized adult age by carapace wear. Older females tended to spawn earlier in the season and more frequently than young females, but those tendencies were more apparent in 2004 when spawning overall occurred earlier than in 2005 when spawning was delayed possibly due to decreased water temperatures. Timing of initial spawning within a year was correlated with water temperature. After adjusting for day of first spring tide, the day of first spawning was 4 days earlier for every 1 degree (̊C) rise in mean daily water temperature in May. Seventy nine % of spawning occurred during nighttime high tides. Fifty five % of spawning occurred within 3 d of a spring tide, which was slightly higher than the 47% expected if spawning was uniformly distributed regardless of tidal cycle. Within the same spawning season, males and females were observed spawning or intertidally resting at more than one beach separated by >5 km. Between years, most (77%) did not return to spawn at the same beach. Probability of stranding was strongly age dependent for males and females with older adults experiencing higher stranding rates. Horseshoe crabs staging in the shallow waters east of the channel spawned exclusively along the eastern (NJ) shoreline, but those staging west of the channel spawned throughout the bay. Overall, several insights emerged from the use of radio telemetry, which advances our understanding of horseshoe crab ecology and will be useful in conserving the Delaware Bay horseshoe crab population and habitats.

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