The reproduction strategies and colour variability of male breeding plumage in the pied flycatcher (Ficedula hypoleuca). Possible ways of maintenance of a phenotype population structure

摘要

The study was conducted on Ladoga Lake Coast in Nijnesvirskiy Reserve (61 deg N 33 deg E) during 1994-1995 years on polymorphic population of the pied flycatcher Ficedula hypoleuca Pall. Influence of the male plumage colour on male fitness components (reproduction time, clutch size and it's efficiency, sizes, weight, fat content and condition of the parents in different stages of a breeding cycle, and nestlings before fledging) was estimated. Indexes of 93 males, 78 females and 369 nestlings from 71 nests have been analyzed. A mean value of male plumage coloration, assessed by Drost's scale (Drost, 1936) made 3.42 in 1994 and 3.98 in 1995. In both young and old males the type of coloration was connected with the breeding status. Males, taking pan in reproduction, on average had brighter coloration, than those which mate. Bright males were characterized by earlier reproduction time and it's smaller variation. The fecundity parameters were not connected with the coloration type. In the whole sample bright males (1-2 type of Drost's score) exceeded intermediate (3-4) and pale (5-7) colored ones in weight and condition of their females and nestlings. Nevertheless bright and pale colored males had similar high fitness parameters of their females and descendants whereas males of intermediate colour remained on a low level in these fitness characters. The fitness components of light birds in a considerably greater degree are controlled be environmental factors. It is supposed, that preservation of light males in populations results from disruptive selection in combination with migrations between different populations in spite of weak sexual selection favoring bright males.