Jenni and Winkler contd. Chapter 3 is the core of the book and is 90 pages long. It deals with the processes of feather growth, physiology, energetics, and control during the moult. The upshot of it all is that the main burden of the moult is decreased performance and increased vulnerability. Reduced activity, especially close to safe feeding ground, can compensate for the added costs of moult.
There are lots of incidentals. These from 3.1 to 3.3 (3.4 to 3.6 to follow separately). Feathers grow at a similar rate both day and night, and the growth rate is almost linear apart from at the very start and the very end. Feathers and associated material (such as the sheath on a pin feather) are 90-95% protein. Besides the protein synthesis for new feathers, whole body protein turnover is greatly accelerated - but little is known about the functional significance of these changes to whole body protein metabolism. A protein-poor diet depresses feather growth rate and quality, and the immune reaction; it seems that when resources are limited, moult and immunity are in competition for energy and/or protein. The relationships between moult and immunity are described as 'somewhat bewildering' (p. 107).
Feather quality is the first thing to suffer from adverse environmental conditions.
Moult is accompanied by a substantial expansion of the vascular system and blood volume, and an increased body water content and turnover. As an aside, independently I have noticed that I have to refill waterers more at this time of year, and that explains it.
. It has eco-support , tour, sport , and turbo. Going up hill or with a strong wind in front I choose turbo. Having both could be problematic with an ordinary electric bike. 
