Hoe hebben Zwarte Mezen Parus ater Drenthe veroverd, en hoe vergaat het ze nu?
Drentse vogels , Volume 21 - Issue 1 p. 64- 73
In the 19th century, Drenthe used to be a province with very few woods. Coal Tits were first observed between 1913 and 1919, but up to 1960 observations in the breeding season remained scarce. Large forestries, mainly with coniferous trees, were planted in the 1940s, and the initial scarcity of the species can be interpreted as lack of suitable habitat. Maturing forests eventually facilitated the settlement of Coal Tits, and an increase, in coniferous woodland. The first breeding bird survey in SW Drenthe, in 1970, already revealed 2492 pairs in an area of23,500 ha (of which 5718 ha covered with conifers). Monitoring of small plots since 1968 showed that Coal Tits peaked around 1970, then decreased consistently through the mid-2000s. Fluctuations in between were apparendy not correlated with severity of winter weather, irruptions or reproductive output. The long-term decline since the early 1970s can be entirely attributed to the decline in surface area of coniferous woodland, mosdy resulting from selective harvesting, selective management (removal of nonnative conifers) and windfall during storms
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