The Effect of Kleptoparasitic Bald Eagles and Gyrfalcons on the Kill Rate of Peregrine Falcons Hunting Dunlins Wintering in British Columbia

The Condor ◽  
2012 ◽  
Vol 114 (2) ◽  
pp. 290-294 ◽  
Keyword(s):  
British Columbia ◽  
Bald Eagles ◽  
Peregrine Falcons ◽  
Kill Rate

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.

scholarly journals Bald Eagles, Haliaeetus leucocephalus, Feeding on Spawning Plainfin Midshipman, Porichthys notatus, at Crescent Beach, British Columbia

2003 ◽  
Vol 117 (4) ◽  
pp. 601 ◽  
Author(s):  
Kyle Hamish Elliott ◽  
Christina L. Struik ◽  
John E. Elliott
Keyword(s):  
British Columbia ◽  
Nous Avons ◽  
Food Source ◽  
Haliaeetus Leucocephalus ◽  
Potential Importance ◽  
Bald Eagles ◽  
Porichthys Notatus ◽  
Tide Height ◽  
Consumption Rates ◽  
Plainfin Midshipman

We observed Bald Eagles feeding on Plainfin Midshipman near Crescent Beach, British Columbia, in May and June 2001 and 2002. We quantified consumption rates and eagle numbers during this period, illustrating the potential importance of this food source to breeding eagles. Tide height was the only significant factor influencing consumption rates, likely because this variable reflected the availability of midshipman prey.Nous avons observé les Pygargues à tête blanche alimenter sur les Crapauds à nageoire unie près de Crescent Beach, Colombie-Britannique, en maie et juin 2001 et 2002. Nous avons mesuré les cadences de consommation et les nombres de pygargues pendant cette période, illustrant l’importance potentielle de cette source de nourriture pour les aigles. La taille de marée était le seul facteur significatif influençant les cadences de consommation et les nombres de pygargues pendant la période d’étude, probablement parce que cette variable a reflété la disponibilité des crapauds.

Observations of Breeding Bald Eagles in Southeastern British Columbia

The Murrelet ◽  
1984 ◽  
Vol 65 (1) ◽  
pp. 22
Author(s):  
L. Scott Forbes ◽  
Gary W. Kaiser
Keyword(s):  
British Columbia ◽  
Bald Eagles

Variable Reproductive Success of Bald Eagles on the British Columbia Coast

1998 ◽  
Vol 62 (2) ◽  
pp. 518 ◽  
Author(s):  
John E. Elliott ◽  
Ian E. Moul ◽  
Kimberly M. Cheng
Keyword(s):  
British Columbia ◽  
Reproductive Success ◽  
Bald Eagles

scholarly journals Tufted Puffins (Fratercula Cirrhata) Respond to Predation Danger During Colony Approach Flights

The Auk ◽  
2007 ◽  
Vol 124 (1) ◽  
pp. 63-70
Author(s):  
BriAnne Addison ◽  
Ronald C. Ydenberg ◽  
Barry D. Smith
Keyword(s):  
Lower Risk ◽  
Risk Level ◽  
Haliaeetus Leucocephalus ◽  
Falco Peregrinus ◽  
Bald Eagles ◽  
Escape Route ◽  
Activity Rate ◽  
Level Of Activity ◽  
Peregrine Falcons ◽  
Predation Danger

AbstractIn spite of their putative importance in the evolution of certain traits (e.g., nocturnality, coloniality, cliff nesting), the effects of aerial predators on behavior of adult seabirds at colonies have been poorly investigated. We hypothesized that Tufted Puffins (Fratercula cirrhata) respond to danger posed by aerial predators by modifying their behavior to mitigate danger. We observed Tufted Puffins making repeated colony fly-ins and departures and characterized (1) the timing of this behavior, (2) the activity rate (number of birds arriving or departing), and (3) the risk-level of activity, with respect to predation danger posed by Bald Eagles (Haliaeetus leucocephalus) and Peregrine Falcons (Falco peregrinus). As we predicted, we found that Tufted Puffins (1) dilute danger by synchronizing their fly-in and departure activities, (2) reduce fly-in and departure activity rates when predators are present, and (3) switch to lower-risk fly-in activities (e.g., staying over water where they have an escape route from an aerial attack) when predators are present.Réaction de Fratercula cirrhata au Danger de Prédation au cours des Vols d'Approche de la Colonie

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.

POISONING OF BALD EAGLES AND RED-TAILED HAWKS BY CARBOFURAN AND FENSULFOTHION IN THE FRASER DELTA OF BRITISH COLUMBIA, CANADA

1996 ◽  
Vol 32 (3) ◽  
pp. 486-491 ◽  
Author(s):  
J. E. Elliott ◽  
K. M. Langelier ◽  
P. Mineau ◽  
L. K. Wilson
Keyword(s):  
British Columbia ◽  
Bald Eagles
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