Invloed van koude-inval op trekkende Kieviten Vanellus vanellus in Drenthe in maart 2013

Dijkstra B. 2013. Impact of cold spell on migrating Lapwings Vanellus vanellus in Drenthe in March 2013. Drentse Vogels 27: . A cold spell in March 2013, at a time that migration of Lapwings had been in full swing, forced the birds to adapt, especially regarding foraging behaviour and use of foraging habitats. A total surface area of 251 km² was censused between 26 and 30 March (during the last two days, temperatures had improved somewhat and movements of Lapwings were again recorded). A total of 9003 Lapwings in 689 flocks were counted, with average densities highest in closed landscapes (0.40 birds/ha), lowest in open landscapes (0.19 birds/ha) and intermediate (0.38 ha) in half-open landscapes. The birds largely avoided open grasslands. Many birds were recorded close to human habitation, even in city centres on lawns, on village greens, in farmyards, soccer fields, industrial parks, athletic tracks and sports fields. As soon as temperature increased, migration was resumed and Lapwings departed their unusual foraging habitats in favour of more open landscapes. The cold spell of March 2013 was apparently not sufficiently severe to cause excessive mortality, as no reports were received of emaciated birds (unlike previous instances of cold spells). However, the shift from open to closed landscapes may have caused extra mortality from predation, as Lapwings figured more prominently in Goshawk diets in Drenthe in 2006, 2012 and 2013, coinciding with a cold March (but previous peaks in Lapwing predation in the 1980s and 1990s were only coincident with a cold March in two out of five years). The 2013 incident reminded of a similar cold spell in 2006 (Dijkstra 2006), another one in 1928 (Brouwer 1928), and several others mentioned in the Dutch ornithological literature and unpublished (accompanied with high mortality).