Limosa article summary      



VAN TURNHOUT C, ENTERS A, VAN NEE W & NIENHUIS J (2017) Trends in breeding success of White Storks Ciconia ciconia in the Netherlands. LIMOSA 90 (4): 178-185.

The White Stork almost disappeared as a breeding bird from the Netherlands in the 1970s, as a result of droughts at the subSaharan wintering sites, hunting, agricultural intensification, use of pesticides and collisions with power lines. Following Swiss and French initiatives, BirdLife Netherlands started a reintroduction program for the White Stork in 1969, which ran until 2009. As a result, the population grew from less than 10 breeding pairs in the 1970s to 100 in 1990 and 950-1050 pairs in 2016 (Fig. 1). As part of the program, nesting localities and breeding success were monitored annually. Here, we analyze trends in productivity of White Storks based on 8900 nest records (on average 397 nests per year in 1995-2017, range 108-775), evenly distributed over its expanding Dutch range (Fig. 2). Furthermore, we explore environmental factors underlying the variation in breeding success.
Overall productivity was on average 2.1 fledged young per successful nest (SD=0.9; N=5048) and 1.6 fledged young per nest when taking all monitored nests into account (SD=1.2; N=6890). This is relatively low compared to the productivity in many other European countries. Moreover, the number of fledged young in the Netherlands has significantly decreased in the period 1995-2017, from 2.3 to 1.9 fledged young per successful nest (Fig. 3). Several factors show a rather weak but significant correlation with the number of fledged young per nest: provisioning of supplementary food (positive; Fig. 4A), distance to the closest feeding station (negative, although lowest within 300 m radius; Fig. 4B), abundance of Common Voles Microtus arvensis (positive), amount of precipitation in May (negative), June and July (positive), average temperature in April (negative), sedentary behaviour of parents (positive, compared to parents that migrated) and arrival date of migrating parents (negative) (Tab. 1). In-depth analyses are necessary to gain more insight in the importance of these factors, because some of the relations are intercorrelated.

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