Paarsgewijs en solitair overnachten van Spreeuwen Sturnus vulgaris buiten de broedtijd

Summary Bijlsma R.G. 2013. Solitary and pairwise roosting of Starlings Sturnus vulgaris in the non-breeding season. Drentse Vogels 27: . In western Drenthe, fledging date of Starlings breeding in woodland averaged 22 May (based on 70 nests in 1990-2003), with pairs taking their fledglings to the nearest grasslands (600 m away and farther). Breeding sites are devoid of Starlings until mid-September, when one of the breeding sites (with up to 11 breeding pairs in summer) was again occupied by singing Starlings. Between 1990 and 2003, this site attracted 1-27 Starlings in early morning, from sunrise till up to an hour afterwards. Normally, autumnal presence covered the period between mid-September and late October/early November, occasionally even later. At this site, four solitary roosting sites were detected in abandoned woodpecker cavities (two of which had been used by nesting Starlings in summer). Departure from the solitary roost was around sunrise (Fig. 1). One cavity was used by a single Starling, later on by two birds (and eventually taken over by Great Spotted Woodpecker Dendrocopos major). The number of autumnal Starlings at solitary roosting sites correlated with the number of pairs having nested there during summer (perhaps indicating that the same birds were involved), both showing a decline towards complete loss in the 2000s. It is thought that habitat degradation in nearby farmland is the main cause of this loss, as grasslands have been converted into ‘nature’ and, if not, have been subjected to intensified management resulting in dry monocultures (presumably with lower invertebrate biomass, although this was not quantified). The decline is typical of Starlings in this part of Drenthe.