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 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 Ecological interactions and habitat modification in nesting Common Murres, Uria aalge

1996 ◽  
Vol 6 (3) ◽  
pp. 261-269 ◽  
Author(s):  
Julia K. Parrish ◽  
Robert T. Paine
Keyword(s):  
Reproductive Output ◽  
Habitat Modification ◽  
Haliaeetus Leucocephalus ◽  
Uria Aalge ◽  
Ecological Interactions ◽  
Bald Eagles ◽  
Predator Removal ◽  
Common Murre ◽  
Corvus Caurinus ◽  
Common Murres

SummarySeabird populations suffer from a variety of natural and human-induced sources of mortality and loss of lifetime reproductive output. On the outer coast of Washington State, Common Murre Uria aalge populations have been in decline for approximately the last decade and are currently reproductively active only at Tatoosh Island. These murres nest in two basic habitat types: crevices (25% of the population) and larger cliff-top subcolonies (75%). Murres in cliff-top subcolonies have suffered dramatic reductions in reproductive success in recent years relative to conspecifics nesting in the crevices, primarily due to egg predation by Glaucous-winged Gulls Larus glaucescens and Northwestern Crows Corvus caurinus, facilitated by the presence of Bald Eagles Haliaeetus leucocephalus. Because predator removal is not feasible and creation of additional crevice habitat is difficult, expensive and potentially ineffective, we have designed a temporary habitat modification (the “silk forest”) which replaces the natural vegetation cover and modifies the interaction between murres and eagles. Within the test subcolony, murres nesting under and immediately adjacent to the silk forest produced nearly twice as many eggs per square metre as their conspecifics nesting in adjacent exposed-ground areas.

Reproductive success of bald eagles (Haliaeetus leucocephalus) and its association with habitat or landscape features and weather in southeast Alaska

1997 ◽  
Vol 75 (10) ◽  
pp. 1595-1604 ◽  
Author(s):  
Scott M. Gende ◽  
Mary F. Wilson ◽  
Mike Jacobsen
Keyword(s):  
Early Spring ◽  
Average Density ◽  
Nesting Success ◽  
Egg Laying ◽  
Haliaeetus Leucocephalus ◽  
Bald Eagles ◽  
Active Nest ◽  
Southeast Alaska ◽  
Landscape Features

Long-term data have been collected on nesting bald eagles (Haliaeetus leucocephalus) in three areas of southeast Alaska. The average density of active nests was among the highest recorded, but nest productivity (average number of young fledged per active nest) and success (percentage of active nests that fledged at least one young) were similar to values in other areas. Using logistic regression, nest productivity was associated with several habitat or landscape features (productivity was highest in proximity to spawning herring and at a particular location), each of which could be related to the availability of prey (fish) in the early spring (April, May) during egg laying and incubation. Consistency of nesting success was associated with the presence of tidal flats at one study site. Nest use, but not nesting success, was related to nesting success the previous year. Multiple regression showed that fewer nests per kilometre were successful in years with a high frequency of spring rains.

Bald Eagle Lead Exposure in the Upper Midwest

2014 ◽  
Vol 5 (2) ◽  
pp. 208-216 ◽  
Author(s):  
Sarah E. Warner ◽  
Edward E. Britton ◽  
Drew N. Becker ◽  
Michael J. Coffey
Keyword(s):  
Lead Poisoning ◽  
Lead Exposure ◽  
Clinical Signs ◽  
Local Environment ◽  
Bald Eagle ◽  
Haliaeetus Leucocephalus ◽  
Upper Midwest ◽  
Bald Eagles ◽  
Potential Source ◽  
Liver Lead Concentration

Abstract In 2012, we examined lead exposure in 58 bald eagles Haliaeetus leucocephalus found dead in Iowa, Minnesota, and Wisconsin. We determined lead concentrations in livers, examined differences in exposure among ages and between sexes, and recorded clinical signs consistent with lead poisoning. Most (60%) of the bald eagles had detectable lead concentrations, and 38% of the 58 had concentrations within the lethal range for lead poisoning. We found no differences in exposure based on sex or age, but we did find an inverse relationship between body and liver mass and liver lead concentration. The high percentage of lead-exposed bald eagles encouraged us to further examine potential sources of lead in our local environment. We initiated a study on the Fish and Wildlife Service's Upper Mississippi River National Wildlife and Fish Refuge to investigate if discarded offal piles from hunter-killed deer were a potential source of lead exposure to scavenging wildlife such as the bald eagle. Radiographs showed that 36% of offal piles in our sample area contained lead fragments ranging from 1 to 107 particles per pile. Our study indicated that 1) lead exposure rates for bald eagles found dead in our Upper Midwest study area were high, 2) more than one-third of the bald eagles found dead in Iowa, Minnesota, and Wisconsin had liver lead concentrations consistent with lead poisoning, and 3) discarded offal piles from deer shot with lead ammunition can be a potential source of lead exposure for bald eagles.

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.

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