scholarly journals Raptor Predation on Wintering Dunlins in Relation to the Tidal Cycle

The Condor ◽  
2004 ◽  
Vol 106 (2) ◽  
pp. 415-419 ◽  
Author(s):  
Dick Dekker ◽  
Ron Ydenberg
Keyword(s):  
Success Rate ◽  
Tidal Cycle ◽  
High Tide ◽  
Falco Peregrinus ◽  
Shore Zone ◽  
Calidris Alpina ◽  
Peregrine Falcons ◽  
Kill Rate ◽  
Circus Cyaneus ◽  
Lines Of Evidence

AbstractAt Boundary Bay, British Columbia, Canada, Peregrine Falcons (Falco peregrinus) captured 94 Dunlins (Calidris alpina) in 652 hunts. The two main hunting methods were open attacks on flying Dunlins (62%) and stealth attacks on roosting or foraging Dunlins (35%). Peregrines hunted throughout the day, yet the kill rate per observation hour dropped 1–2 hr before high tide and peaked 1–2 hr after high tide. The drop in kill rate coincided with the departure of the mass of Dunlins for over-ocean flights lasting 2–4 hr. The peak in kill rate occurred just after the tide began to ebb and the Dunlins returned to forage in the shore zone. The hypothesis that closeness to shoreline vegetation is dangerous for Dunlins is supported by three converging lines of evidence: (1) the high success rate (44%) of peregrine hunts over the shore zone compared to the rate (11%) over tide flats and ocean; (2) the high kill rate per observation hour at high tide; and (3) the positive correlation of kill rate with the height of the tides. Seven of 13 Dunlins killed by Merlins (Falco columbarius) and all five Dunlins killed by Northern Harriers (Circus cyaneus) were also captured in the shore zone.Depredación de Calidris alpina por Rapaces durante el Período Invernal con Relación al Ciclo de la MareaResumen. En la Bahía Boundary, Columbia Británica, Canadá, halcones Falco peregrinus capturaron 94 ejemplares de Calidris alpina en 652 horas. Los dos métodos principales de caza fueron ataques abiertos sobre individuos que estaban volando (62%) y ataques encubiertos sobre individuos que estaban posados o forrajeando (35%). F. peregrinus cazó a lo largo del día, pero la tasa de matanza por hora de observación disminuyó 1–2 hr antes de la pleamar y alcanzó un máximo 1–2 hr después de la pleamar. La caída en la tasa de matanza coincidió con la partida en masa de C. alpina para realizar vuelos sobre el océano que duraron 2–4 hr. El pico en la tasa de matanza ocurrió justo después de que la marea comenzó a menguar y de que los individuos de C. alpina regresaron a forrajear a la zona de playa. La hipótesis de que la cercanía de la vegetación a la línea de playa es peligrosa para C. alpina es apoyada por tres líneas convergentes de evidencia: (1) la alta tasa de éxito (44%) de las cacerías de F. peregrinus sobre la zona de playa comparada con la tasa (11%) de las cacerías sobre los planos de la marea y el océano; (2) la alta tasa de matanza por hora de observación durante la pleamar; y (3) la correlación positiva de la tasa de matanza con la altura de las mareas. Siete de 13 individuos de C. alpina cazados por F. columbarius y todos 5 individuos de C. alpina cazados por Circus cyaneus también fueron atrapados en la zona de playa.

High-tide flight by wintering Dunlins (Calidris alpina): a weather-dependent trade-off between energy loss and predation risk

2013 ◽  
Vol 91 (1) ◽  
pp. 25-29 ◽  
Author(s):  
Dick Dekker
Keyword(s):  
Predation Risk ◽  
High Tide ◽  
Significant Determinant ◽  
Flight Duration ◽  
Calidris Alpina ◽  
Wind Speeds ◽  
Migratory Shorebirds ◽  
Peregrine Falcons ◽  
The Mean ◽  
The Waves

Migratory shorebirds wintering or staging on ocean coasts collect at high tide on roosting sites that remain above the flood line. However, some species of Calidris sandpipers spend the high-tide interval in flight over the ocean. In the winters of 2006–2012, the characteristics of high-tide flight by Dunlins (Calidris alpina (L., 1758)) were studied at Boundary Bay, British Columbia, Canada. At wind speeds of 1–6 m/s, flocks of Dunlins remained airborne over the ocean for up to 4 h at altitudes of >30 m. If winds were >10 m/s, the Dunlins coursed low over the waves. Ambient temperature was a significant determinant in the occurrence and duration of high-tide flight. In October and November, the Dunlins spent just as much time in flight before as after high tide, but in January, flight duration was 43% shorter after high tide than before high tide. The mean January temperatures were significantly lower than in October and November. The Dunlins were hunted by Peregrine Falcons (Falco peregrinus Tunstall, 1771), which captured 81 prey in 494 attacks. The maximum kill rate of 0.28 captures per hour of observation was recorded in the second hour after high tide, which suggests that predation risk is greatest for Dunlins that return early from high-tide flight.

scholarly journals Kleptoparasitism by Bald Eagles (Haliaeetus leucocephalus) as a factor in reducing Peregrine Falcon (Falco peregrinus) predation on Dunlin (Calidris alpina) wintering in British Columbia

2015 ◽  
Vol 129 (2) ◽  
pp. 159 ◽  
Author(s):  
Dick Dekker ◽  
Mark C. Drever
Keyword(s):  
British Columbia ◽  
River Valley ◽  
Bald Eagle ◽  
Haliaeetus Leucocephalus ◽  
Peregrine Falcon ◽  
Fraser River ◽  
Falco Peregrinus ◽  
Bald Eagles ◽  
Calidris Alpina ◽  
Peregrine Falcons

Kleptoparasitism, or food piracy, is common in a wide range of taxa, particularly among predators, with the larger species forcing smaller species to surrender their catch. The Bald Eagle (Haliaeetus leucocephalus) is known to rob Peregrine Falcons (Falco peregrinus) of just-caught prey. We present time series of kleptoparasitic interactions between eagles and peregrines hunting Dunlin (Calidris alpina) that were wintering at Boundary Bay in the Fraser River valley, British Columbia. In 1108 hours of observation during January, intermittently between 1994 and 2014, we recorded 667 sightings of Peregrine Falcons, including 817 attacks on Dunlin resulting in 120 captures. The population of wintering Bald Eagles in the study area increased from about 200 in 1994 to 1800 in 2014, while the rate of kleptoparasitism at the expense of peregrines increased from 0.05 to 0.20. The increase in the number of Bald Eagles coincided with a decline in January sightings of Peregrine Falcons, which suggests that some falcons may have left the study area because of interference from eagles. The decrease in Peregrine Falcon numbers can be expected to have led to reduced predation risk for Dunlins. Christmas Bird Counts conducted in the Fraser River Valley have underscored the fluctuation in eagle and peregrine numbers reported here.

Extreme waves and surges interaction with tides during storms in winter 2013/2014.

2021 ◽  
Author(s):  
Julia Rulent
Keyword(s):  
Tidal Cycle ◽  
Grid Point ◽  
High Tide ◽  
Water Levels ◽  
Extreme Waves ◽  
Near Shore ◽  
The Uk ◽  
The Waves ◽  
Tidal Stage

<p>The interaction between waves, surges and tides is one of the main drivers of coastal total water levels (TWL).  Understanding this interaction is crucial for studying high TWL formation near shore, and to do this it is important to not only evaluate how high the TWL is but also when and where it occurs.</p><p>In this study we use a high resolution (1.5 km) three-way coupled (waves-atmosphere-ocean) numerical model developed by the MetOffice (UKC4) to study coastal conditions at the UK coast during the extreme events of winter 2013, which was chosen as case study because of the amount of flooding that occurred in relation to storms and surges during this period.</p><p>For each coastal grid point the ten strongest storms of that winter, ranked by the significant wave height (Hs) magnitude, were selected. During these storm periods, the number of hours in which Hs and surges exceeded the 90<sup>th</sup> percentile of winter 2013 were evaluated considering what tidal stage they occurred on. The same was done for instances where high Hs and surges occurred simultaneously. The aim is to understand if specific areas were predominantly affected by one of the TWL components and how Hs and surges interacted with the tide. What was the spatial distribution of the waves, surges, and tides during winter 2013? Did extreme Hs and Surges occur more often over specific stages of the tidal cycle? Did they occur simultaneously? </p><p>In this study we show that during the winter 2013, Hs and surges above the 90<sup>th</sup> percentile value did occur simultaneously at all stages of the tidal cycle. They more often occurred together over the rising tide with in average 8.7% and 8.6% of instances found two and three hours before high tide. In 7.7% of cases high wave and surges also concurred at high tide.</p>

Identification of Natal Locales of Peregrine Falcons (Falco peregrinus) by Trace-Element Analysis of Feathers

The Auk ◽  
1983 ◽  
Vol 100 (3) ◽  
pp. 560-567 ◽  
Author(s):  
Jimmie R. Parrish ◽  
David T. Rogers ◽  
F. Prescott Ward
Keyword(s):  
Trace Elements ◽  
Trace Element ◽  
Trace Element Analysis ◽  
Trace Element Content ◽  
Falco Peregrinus ◽  
Element Analysis ◽  
Peregrine Falcons ◽  
Geographic Origins ◽  
Multivariate Discriminant ◽  
Discriminant Function Analyses

Abstract Samples of secondary remiges collected from nestling Peregrine Falcons (Falco peregrinus) in Alaska and western Greenland were analyzed for trace-element content using instrumental neutron-activation analysis. Concentrations of 14 trace elements were subjected to a series of multivariate discriminant function analyses to ascertain whether or not these concentrations could be used to identify the geographic origins of the birds sampled. Individual falcons from the three areas studied can be placed in their proper natal locale with 100% predictability. Mercury (Hg) was the best individual discriminator for separating sample groupings. Aluminum (A1) and Vanadium (V), in conjunction with Hg, provided the most discriminant trio of elements when various groupings of element concentrations were considered as predictors.

A Large Aggregation of 50 Peregrine Falcons (Falco peregrinus) During Migration in the Western Gulf of Mexico

2018 ◽  
Vol 52 (4) ◽  
pp. 500-502 ◽  
Author(s):  
Silvan T. Paganini ◽  
Amanda Stafford ◽  
Johann von Hirschheydt ◽  
Marc Kéry
Keyword(s):  
Gulf Of Mexico ◽  
Falco Peregrinus ◽  
Large Aggregation ◽  
Peregrine Falcons

Avipoxvirus infection in peregrine falcons (Falco peregrinus) from a reintroduction programme in Germany

2004 ◽  
Vol 154 (4) ◽  
pp. 110-113 ◽  
Author(s):  
O. Krone ◽  
S. Essbauer ◽  
G. Wibbelt ◽  
G. Isa ◽  
M. Rudolph ◽  
...  
Keyword(s):  
Falco Peregrinus ◽  
Peregrine Falcons

scholarly journals Legacy or colonization? Posteruption establishment of peregrine falcons (Falco peregrinus) on a volcanically active subarctic island

2016 ◽  
Vol 7 (1) ◽  
pp. 107-114 ◽  
Author(s):  
Sarah A. Sonsthagen ◽  
Jeffrey C. Williams ◽  
Gary S. Drew ◽  
Clayton M. White ◽  
George K. Sage ◽  
...  
Keyword(s):  
Falco Peregrinus ◽  
Peregrine Falcons
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