INTERMEDIATE CLUTCHES IN THE STARLING (STURNUS-VULGARIS) - REPLACEMENT CLUTCHES, ADDITIONAL CLUTCHES OF POLYGYNOUS MALES OR LATE 1ST CLUTCHES

Literature on the breeding biology of the Starling Sturnus vulgaris refers to a sequence of egg-layings usually termed as first, intermediate and second broods. Egg-laying of first broods is highly synchronous. Accurate data concerning the identity of pairs producing the intermediate clutches, i.e. clutches that are laid in the period between the first and second brood layings, are lacking. These clutches are considered to be mainly replacement clutches of early clutches that failed. In this paper, we analyse the degree of synchronization of first layings during 5 breeding seasons and determine the identity of pairs producing intermediate clutches. The synchronized laying period of the first brood varied from 3 to 9 days. The percentage of intermediate clutches ranged from 14 % to 66 %. Only few intermediate clutches were replacement clutches of early clutches that failed. Most (95 %) were additional clutches of early breeding polygynous males or clutches of males that arrived only during the incubation or nestling period of the early breeding pairs (i.e. pairs being involved in a brood, initiated during the synchronized first brood period). The late arriving males and females may have been birds that migrated further than these being involved in a first brood, and consequently returned later in the season. The arrival of new males and females after the synchronized laying period of the first brood therefore may be a typical phenomenon for Continental Europe where starlings are mainly migratory. © 1990 Verlag der Deutschen Ornithologen-Gesellschaft.