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Adaptations Of The Gray Catbird Dumetella Carolinensis To Long Distance Migration: Energy Stores And Substrate Concentrations In Plasma, Richard Marsh
Adaptations Of The Gray Catbird Dumetella Carolinensis To Long Distance Migration: Energy Stores And Substrate Concentrations In Plasma, Richard Marsh
Richard Marsh
The major body components (water, lean dry, and fat) were measured in the carcasses of Gray Catbirds from which the flight muscles had been removed. Birds were collected from May through October near Ann Arbor, Michigan and during September and October near Gainesville, Florida. Additionally, the glycogen content of muscle and liver and the concentrations of glucose and triglycerides in plasma were determined in catbirds sampled during fall migration in Florida. Catbirds attained maximum body masses of ∼50 g in Florida, largely due to the addition of fat. Relatively lean birds (∼3-4% body fat) in spring through fall weighed approximately …
Adaptations Of The Gray Catbird Dumetella Carolinensis To Long-Distance Migration: Flight Muscle Hypertrophy Associated With Elevated Body Mass, Richard L. Marsh
Adaptations Of The Gray Catbird Dumetella Carolinensis To Long-Distance Migration: Flight Muscle Hypertrophy Associated With Elevated Body Mass, Richard L. Marsh
Richard Marsh
The size and composition (lean-dry, water, and fat contents) of the flight muscles of the catbird were investigated as a function of the large seasonal changes in body mass which occur in this species. The mass of the pectoralis muscle is highly positively correlated with body mass, leading to an elevation in muscle mass of ∼35% during fall premigratory fattening. The changes in muscle mass are brought about by coordinated variations in all major components of the muscles which were measured. High-oxidative, fast-twitch fibers represent 88% of the total fibers in the pectoralis muscle. The cross-sectional area of the muscle …