Abstract
Moult of feathers entails considerable physiological and energetic costs to an avian organism. Even under favourable feeding conditions, endogenous body stores and energy reserves of moulting birds are usually severely depleted. Thus, most species of birds separate moult from other energy-demanding activities, such as migration or reproduction. Common snipe Gallinago gallinago is an exception, as during the first autumn migration many young snipe initiate the post-juvenile moult, which includes replacement of body feathers, lesser and median wing coverts, tertials, and rectrices. Here, we evaluated moult-related changes in blood plasma biochemistry of the common snipe during a period of serious trade-off in energy allocation between moult and migration. For this purpose, concentrations of basic metabolites in plasma were evaluated in more than 500 young snipe migrating through Central Europe. We found significant changes in the plasma concentrations of total protein, triglyceride and glucose over the course of moult, while the concentrations of uric acid and albumin did not change. Total protein concentration increased significantly in the initial stage of moult, probably as a result of increased production of keratin, but it decreased to the pre-moult level at the advanced stage of moult. Plasma triglyceride concentration decreased during the period of tertial and rectrice moult, which reflected depletion of endogenous fat reserves. By contrast, glucose concentration increased steadily during the course of moult, which could be caused by increased catabolism of triglycerides (via gluconeogenesis) or, alternatively, due to increased glucocorticoids as a stress response. Our results suggest that physiological changes associated with moult may be considered important determinants of the low pace of migration typical of the common snipe.
Highlights
Moulting is a process by which the birds maintain feathers in good quality, which improves birds’ flight performance and enhances thermoregulation
At least some of these changes in blood plasma biochemistry are likely associated with the use of energy and nutrients during plumage synthesis or during other moult-related metabolic processes which greatly contribute to the overall costs of moult
It has been shown that deposition of protein as keratins of feathers may equal a quarter or more of the total protein mass of the bird (Newton, 1968; Murphy & Taruscio, 1995; Roman et al, 2009)
Summary
Moulting is a process by which the birds maintain feathers in good quality, which improves birds’ flight performance and enhances thermoregulation. These additional metabolic processes include recrudescence of the integument, cyclic osteoporosis, and an increased whole-body protein turnover, which may add up to daily energy costs of peak moult exceeding 50% of basal metabolic rate (Murphy & King, 1992). The energy deposited daily as keratins in feathers was estimated to equal only ca. 10% of the energy costs of moult and much higher energy costs were associated with protein metabolism not directly related to keratin synthesis (Murphy & Taruscio, 1995)
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Free) 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a call
