BRANTA — Simon Gillings

Diurnal and nocturnal ecology of Golden Plovers Pluvialis apricaria and LapwingsVanellus vanellus wintering on arable farmland

Institution: University of East Anglia, Norwich, UK
Supervisors: WJ Sutherland, RJ Fuller (BTO)
Details: PhD 2003 (Completed)

Address: BTO, The Nunnery, Thetford, Norfolk, IP24 2PU, UK (Oct 2012) Email

Subject Keywords: habitat selection, agriculture, nocturnal;
Species Keywords: Eurasian Golden Plover Pluvialis apricaria, Northern Lapwing Vanellus vanellus

 

Abstract

During winter, Golden Plovers and Lapwings are two of the most widespread wader species in north-western Europe where they occupy lowland farmland. Previous studies have demonstrated strong preference for feeding on earthworms in pastures but large numbers of plovers occupy arable farmland systems. This thesis investigates the importance of arable farmland in a national context and aims to determine and understand the basis of diurnal and nocturnal patterns of abundance, distribution and habitat selection on arable fields.

Few data sources exist for quantifying winter trends and distribution. Estuarine counts from the Wetland Bird Survey show a large increase in the number of both Golden Plovers and Lapwings, with the trend being particularly pronounced on the east coast. The recent Winter Farmland Bird Survey, which mapped plovers and other farmland birds throughout lowland Britain, showed that the distribution is more biased towards eastern Britain than was the case 15-30 years ago. Together these two large-scale surveys indicate that arable farmland is increasingly important for wintering plovers.

Intensive studies over six winters in south Norfolk showed that substantial numbers of plovers used arable fields, with diurnal flocks numbering hundreds to thousand of birds using cereal crops, bare till and harvested sugar beet fields and largely avoiding pasture. Diurnal feeding was reduced during full moon periods although this was over-ridden by cold weather. Only a very small proportion of fields were used during the day in marked contrast to the distribution at night when smaller flocks used many more fields and different habitat types, with implications for the minimum area required. Nocturnal surveys also revealed that plovers were active on all nights irrespective of moon phase.

The diet on arable fields consisted largely of small beetles, millipedes and earthworms, though earthworms were of major energetic value. Diurnal intake rates were similar to previous studies, being determined partly by prey abundance but there was much unexplained variation within and between fields. A novel technique was developed for assessing ground visibility for these pause-travel foragers and showed that prey detectability could differ markedly between fields due to vegetation and soil structure. Nocturnal intake rates were higher than diurnal intake rates owing to the consumption of more large earthworms at night. An energetic model showed that diurnal intake rates alone were insufficient to meet daily requirements and that nocturnal feeding was essential. This implies that understanding nocturnal ecology and the differences in field and habitat selection between day and night are essential for effectively managing Golden Plovers and Lapwings.

 

Published Papers

Gillings, S., Fuller, R.J. & Sutherland, W.J. in press. Diurnal studies do not predict nocturnal habitat choice and site selection of Eurasian Golden Plovers Pluvialis apricaria and Northern Lapwings Vanellus vanellus. Auk
Gillings, S., Austin, G.E., Fuller, R.J. & Sutherland, W.J. in press. Distribution shifts in wintering Golden Plovers Pluvialis apricaria and Lapwings Vanellus vanellus in Britain. Bird Study
Gillings, S. 2004. Prey detectability: significance and measurement using a novel laser pen technique. Wader Study Group Bulletin 103: 50-55.
Butler, S.J. & Gillings, S. 2004. Quantifying the effects of habitat structure on prey detectability and accessibility to farmland birds. Ibis 146(Suppl. 2): 123-130.
Gillings, S. 2003. Plugging the gaps – winter studies of Eurasian Golden Plovers and Northern Lapwings. Wader Study Group Bulletin 100: 25-29.
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