The aim of the paper is limited to a rough describing peculiarities of relations between fat deposit level and the body mass as well as a seasonal and diurnal dynamics of catching at an inland study site located far to the North from important geographical barriers on the Sedge Warbler migration to Central Africa. Material was collected in 1999 and 2000 from July (11 Jul. 1999 and 28 Jul. 2000) till 29 August in L'viv province (western Ukraine). In the present paper 1066 Sedge Warblers caught in 1999 and 407 ones caught in 2000 were taken under consideration. Their body mass and fat score were recorded according to rules published by Busse (1983, 2000). During elaboration of the data the idea of body mass standardisation for a defined fat score (
In both years adults were highly significantly heavier than immatures. This finding leads to conclusion that summarising data for adult and immature Sedge Warblers in calculation of body mass correction values would result in significant growth of variance. Having compared the body mass in years 1999 and 2000 a pronounced difference between immatures was found. In 1999 the first period of migration was characterised by relatively high representation of adults (16.8%) and a low fat level (average fat score
Analysing changes of the fat load and the body mass one must keep in mind that observed differences in the fat scores of birds caught in different parts of a day could be caused by two separate processes: (1) feeding and accumulation of fuel reserves (passing borders set in a fat scoring procedure) and (2) possible differentiation of the diurnal activity of birds that already have different levels of stored fat.