Broedende Goudhaantje Regulus regulus bereiken topaantallen in ZW-Drenthe in 1999-2000

Standardized monitoring of breeding birds in ten woodland and three heathland plots (4382 ha, including 1000 ha of coniferous woodland) in SW-Drenthe since 1968 revealed a sudden and steep increase of Goldcrest numbers in 1999-2000, to population levels that were higher than ever before (Figure 1, Table 1). Goldcrests fluctuated widely over the years, with high numbers in 1970-72, 1982-83 and 1999-2000 and low numbers in 1973- 74, 1986 and -more or less- in 1991-92. To some extent, high numbers coincided with periods of mild winters and low numbers with severe or cold winters. Low numbers in 1973-74, however, were related to gales in 1972 and 1973, which wreaked havoc among conifer plantations (especially douglas fir and Norway spruce). Despite a 12%-loss of favoured habitat since 1972, overall densities in 1970-78 matched those in 1994-2000, i.e. 3.1 respectively 3.4 pairs/10 ha. In 1999-2000 highest densities (of 18.0-24.5 pairs/10 ha) were recorded in 30-60 year old plantations of Picea abies and Pseudotsuga menziesii (Table 2). In general, these densities concur with densities found elsewhere in Europe. Besides severity of winters, population changes probably are related to weather conditions during and after the breeding season and availability of food, but their impact remains unknown. The population of Goldcrests in the province of Drenthe is estimated at c. 15.000 pairs, slightly more than the maximum of 12.000 pairs in 1978-93.