VAN TURNHOUT C, NIENHUIS J, MAJOOR F, OTTENS G, SCHREVEN K & SCHOPPERS J (2016) Breeding performance of Common Starlings Sturnus vulgaris. LIMOSA 89 (1): 37-45.

The Dutch breeding population of Common Starling has declined with on average 4% annually in 1984- 2014. Since demographic data are scarce, we collected data on breeding performance in 2014 and 2015. In these years 558 respectively 353 nest records were submitted by dedicated volunteers, far more than the average of 55 per year in 1984-2013. Mean laying date of first clutches was 3 April in 2014, and 13 April in 2015, the latter being similar to the mean laying date in 2000- 13. Before 1990, the mean laying date was a week later. In addition to a very early start of egg-laying, the second brood peak was remarkably large in 2014, and was estimated to comprise 48% of the number of nests in the first brood peak (early broods). In earlier years or periods the relative size of the second brood peak was much smaller: 11, 6, 10, 20 and 11% in 1960-79, 1980-89, 1990-99, 2000-2013 and 2015, respectively. Although firm evidence is lacking, we think that the second brood peak consisted mainly, but not exclusively, of true second broods. The relative size of the second brood peak was strongly positively related to the mean laying date of the first clutch, which in turn was tightly correlated with mean temperature in March-April. In 2014 and 2015, 94% and 86% of early clutches resulted in at least one fledged young, while 76% and 54% of late clutches did. Averaged over all years, nest success of early and late attempts was 83% and 78% respectively. In 2014 and 2015, on average 4.7 and 4.8 young fledged per successful nest in early broods, and a significantly lower 3.6 and 3.8 in late broods. Averaged over all years, the number of fledglings per successful nest was 4.5 for early and 3.5 for late broods. We found no indications that the breeding performance of Starlings in The Netherlands has decreased during the past decades. Therefore, the population decline must have another cause. Indeed, a separate analysis of ring recoveries has shown that the survival of first year Starlings has strongly declined during the period of population decline.

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