Body composition of wintering canvasbacks in Louisiana: dominance and survival implications

Article Abstract:

A study was conducted on the effects of sex, age and month on Canvasback body mass and composition. Specimens examined were obtained from Catahoula Lake (CL) and the Mississippi River Delta (MRD), LA. Variations in size-adjusted body mass and fat were found with respect to age, month and site. In early winter, MRD adults were fatter than CL adults, although fat levels increased in all birds until late winter, when they reached equal levels. A positive correlation was found between leg-muscle protein content and body fat changes, but this was not affected by sex or age. Females were not disadvantaged in nutrient acquisition by their smaller size.

Research, Physiological aspects, Natural history, Body composition, Louisiana, Canvasback, Canvasback (Duck)

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Dominance, brood size and foraging behavior during brood-rearing in the Lesser Snow Goose: an experimental study

Article Abstract:

Experimental studies of Lesser Snow Geese, wherein artificially created high-biomass food patches enhanced food availability, revealed that they fed more in high biomass locations, wherein dominance ranking was established mainly by the degree of aggressive behavior of individual adult males of the species. Enhanced consumption rates, mitigated foraging energetic costs and predation risk were the benefits enjoyed by cohesive family units feeding from high biomass food sources.

Food and nutrition, Snow goose, Snow geese

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Status signaling in Dark-eyed Juncos: perceived status of other birds affects dominance interactions

Article Abstract:

The dark color of the head and body plumage in Dark-eyed Juncos indicates dominance and a high social status. Experimental darkening of the plumage of a subordinate bird and lightening of the plumage of a dominant bird reverses the dominance. However, this reversal is probably temporary and is absent in control birds. Individual recognition in these birds does not involve the color of the head and mantle plumage.

Behavior, Observations, Juncos, Color of birds, Bird coloration

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