Started in 1968 rather tentatively, a study of the moulting adult birds caught in Kvismaren began; this is when birds are replacing feathers completely after nesting. As of 1973, almost all the specimens caught in this category are investigated according to their moult. This take place on a special form; a schematic diagram of the wing and tail.
To date, over 10 000 moult cards have been completed and an analysis has been published for a number of species. In Kvismaren the entire moult period is covered for most species. It is therefore possible to obtain very thorough data. In most other locations, moult is only investigated during the latter part of the moult period.
Mostly recorded and analyzed in the Reed Bunting. It was shown, that moult is affected by the weather. The temperature in April and May are significant. Cold years extending the moult period by about 3 days. Extreme conditions, snow in late spring and a hot summer in comparison to a hot spring and cold summer, on average, give a difference in moult period of 10 days. It is also known that females moult faster than males.