Synchronous diving by surf scoter flocks

1985 ◽  
Vol 63 (11) ◽  
pp. 2516-2519 ◽  
Author(s):  
L. E. Schenkeveld ◽  
R. C. Ydenberg
Keyword(s):  
Statistical Method ◽  
Pronounced Effect ◽  
Melanitta Perspicillata ◽  
Data Support ◽  
Surf Scoter ◽  
Average Size ◽  
Larus Glaucescens

We studied the diving and surfacing synchrony of foraging flocks of wintering surf scoters (Melanitta perspicillata). Our data support the hypothesis that synchronous diving is an adaptation that reduces kleptoparasitism by glaucous-winged gulls (Larus glaucescens), which frequently attend foraging flocks. We developed a statistical method for measuring and comparing synchrony between flocks, and applied it to videotape records of 30 flocks. The results show that diving and surfacing are highly synchronous, and that there is a large variation between flocks in the degree of synchrony exhibited. The most pronounced effect is for surfacing synchrony to be higher in the presence of gulls. This seems to arise because individual birds curtail their dives so that less synchrony is lost between diving and surfacing during a group dive. This curtailment of dive length may lead to a reduction in the average size of prey captured.

Surf Scoter (Melanitta perspicillata)

2015 ◽  
Author(s):  
Eric M. Anderson ◽  
Rian D. Dickson ◽  
Erika K. Lok ◽  
Eric C. Palm ◽  
Jean-Pierre L. Savard ◽  
...  
Keyword(s):  
Melanitta Perspicillata ◽  
Surf Scoter

Surf Scoter (Melanitta perspicillata)

1998 ◽  
Author(s):  
Jean-Pierre L. Savard ◽  
Daniel Bordage ◽  
Austin Reed
Keyword(s):  
Melanitta Perspicillata ◽  
Surf Scoter

scholarly journals Observations of Above-Surface Littoral Foraging in Two Sea Ducks, Barrow's Goldeneye, Bucephala islandica, and Surf Scoter, Melanitta perspicillata, in Coastal Southwestern British Columbia

2004 ◽  
Vol 118 (2) ◽  
pp. 264
Author(s):  
Deborah L. Lacroix ◽  
Kenneth G. Wright ◽  
Daniel Kent
Keyword(s):  
British Columbia ◽  
Water Surface ◽  
Foraging Behaviour ◽  
Mytilus Trossulus ◽  
Sea Ducks ◽  
Melanitta Perspicillata ◽  
Bucephala Islandica ◽  
Intertidal Mussel ◽  
Surf Scoter

Barrow's Goldeneyes (Bucephala islandica) and Surf Scoters (Melanitta perspicillata) were observed on four separate occasions, by three different observers, foraging on Bay Mussels (Mytilus trossulus) above the water surface. This unique foraging behaviour could be attributed to diurnal spring tides and reduced lower intertidal mussel abundance.

Duckling survival and use of space by surf scoter (Melanitta perspicillata) broods

Ecoscience ◽  
2008 ◽  
Vol 15 (1) ◽  
pp. 81-88 ◽  
Author(s):  
Louis Lesage ◽  
Austin Reed ◽  
Jean-Pierre L. Savard
Keyword(s):  
Use Of Space ◽  
Duckling Survival ◽  
Melanitta Perspicillata ◽  
Surf Scoter

Observations on the Diving of the Surf Scoter (Melanitta perspicillata)

The Auk ◽  
1957 ◽  
Vol 74 (3) ◽  
pp. 392-394 ◽  
Author(s):  
Philip S. Humphrey
Keyword(s):  
Melanitta Perspicillata ◽  
Surf Scoter

Surf Scoter (Melanitta perspicillata)

2015 ◽  
Author(s):  
Eric M. Anderson ◽  
Rian D. Dickson ◽  
Erika K. Lok ◽  
Eric C. Palm ◽  
Jean-Pierre L. Savard ◽  
...  
Keyword(s):  
Melanitta Perspicillata ◽  
Surf Scoter

Surf Scoter (Melanitta perspicillata)

2020 ◽  
Author(s):  
Eric M. Anderson ◽  
Rian D. Dickson ◽  
Erika K. Lok ◽  
Eric C. Palm ◽  
Jean-Pierre L. Savard ◽  
...  
Keyword(s):  
Melanitta Perspicillata ◽  
Surf Scoter

Grain Refinement in Titanium-Erbium Alloys

1974 ◽  
Vol 32 ◽  
pp. 522-523
Author(s):  
B. B. Rath ◽  
J. E. O'Neal ◽  
R. J. Lederich
Keyword(s):  
Electron Microscopy ◽  
Size Distribution ◽  
Grain Refinement ◽  
Grain Growth ◽  
Volume Fraction ◽  
Pure Titanium ◽  
Systematic Investigation ◽  
Second Phase ◽  
Titanium Matrix ◽  
Average Size

Addition of small amounts of erbium has a profound effect on recrystallization and grain growth in titanium. Erbium, because of its negligible solubility in titanium, precipitates in the titanium matrix as a finely dispersed second phase. The presence of this phase, depending on its average size, distribution, and volume fraction in titanium, strongly inhibits the migration of grain boundaries during recrystallization and grain growth, and thus produces ultimate grains of sub-micrometer dimensions. A systematic investigation has been conducted to study the isothermal grain growth in electrolytically pure titanium and titanium-erbium alloys (Er concentration ranging from 0-0.3 at.%) over the temperature range of 450 to 850°C by electron microscopy.

Discrimination of monomer from multimer DNA disk-shaped toruses by freezeetch TEM

1984 ◽  
Vol 42 ◽  
pp. 210-211
Author(s):  
George C. Ruben ◽  
Kenneth A. Marx
Keyword(s):  
Biochemical Data ◽  
Dna Structures ◽  
Ice Surface ◽  
Double Stranded Dna ◽  
Data Support ◽  
Dna Organization ◽  
Trivalent Cations

In vitro collapse of DNA by trivalent cations like spermidine produces torus (donut) shaped DNA structures thought to have a DNA organization similar to certain double stranded DNA bacteriophage and viruses. This has prompted our studies of these structures using freeze-etch low Pt-C metal (9Å) replica TEM. With a variety of DNAs the TEM and biochemical data support a circumferential DNA winding model for hydrated DNA torus organization. Since toruses are almost invariably oriented nearly horizontal to the ice surface one of the most accessible parameters of a torus population is annulus (ring) thickness. We have tabulated this parameter for populations of both nicked, circular (Fig. 1: n=63) and linear (n=40: data not shown) ϕX-174 DNA toruses. In both cases, as can be noted in Fig. 1, there appears to be a compact grouping of toruses possessing smaller dimensions separated from a dispersed population possessing considerably larger dimensions.

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