Summary1. The golden plover Pluvialis apricaria is of high conservation concern in Europe. Previous studies have concentrated on how birds utilize moorland. We used radiotelemetry to study their habitat selection and behaviour, during both night and day, in an upland landscape of enclosed ®elds and moorland in county Durham, UK. 2. During incubation adult golden plover fed principally in enclosed ®elds 1Á1±3Á7 km from their moorland nests, but spent less than 5% of their foraging time on moorland. In contrast, birds with broods spent around 85% of their time foraging on moorland. 3. Birds on moorland selected calcareous grassland and avoided old stands of dense tall heather (> c. 12 cm). Younger, shorter (< c. 5±8 cm), sparser heather was used as much as would be expected by chance. Mires of harestail cotton grass Eriophorum vaginatum, the dominant community type when heather Calluna vulgaris is heavily grazed, was selected on both moorland sites. 4. Only 17 of 85 ®elds in the study area were used for foraging by breeding golden plover. The number of molehills, a reported indicator of earthworm abundance, was the best single variable explaining ®eld choice. Both ®eld size and distance from road had small but signi®cant e ects on ®eld choice. 5. We advocate that groups of enclosed ®elds regularly used by golden plover during the breeding season be a orded speci®c protection under conservation schemes (e.g. environmentally sensitive area agreements). Conservationists wishing to locate such ®elds should look for areas with high earthworm populations, as indicated by molehills, close (< 4 km) to breeding populations of golden plover. Rank heather on¯at or gently sloping ground should be kept short by appropriate burning or grazing. Areas of calcareous grassland should be preserved. 6. These data illustrate the value of detailed radio-telemetry in informing equally detailed habitat management for important bird species.

1.  A spatial depletion model of the responses of grazing wildfowl to the availability of intertidal vegetation at Lindisfarne National Nature reserve, north‐east England, was used to investigate the capacity of the site’s beds of Zostera and other intertidal vegetation to support brent geese Branta bernicla hrota and wigeon Anas penelope. 2.  Recent total winter counts of brent geese and wigeon were both only 40% of the maximum that the food supply at the site could theoretically support. Other factors must have been restricting their numbers. Earlier arrival of brent geese at the site could increase the number of brent goose‐days which could be supported, but would have only a slight negative effect on the wigeon‐days. 3.  The model was used to examine three conservation issues: encroachment of Spartina anglica, sea level rise and loss of food plants from the whole site (which could result from increased autumn storms or plant disease). Loss from the top of the shore through encroachment by Spartina anglica had the greatest effect on the site’s capacity to sustain geese and wigeon. Loss from the bottom of the shore, as would occur through sea level rise, had less impact. Increased loss of vegetation over the whole site would have an intermediate effect. 4.  This work has important implications for the management of the site. Factors such as hunting, that may be restricting current numbers below those that could be supported by the food supply, require urgent investigation. Model predictions indicate that encroachment of Spartina is likely to depress local populations of brent geese and wigeon under current conditions only if it results in the complete loss of Zostera from the top 500 m of the shore.

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Brent Geese Branta bernicla wintering at Lindisfarne, northeastern England, fed almost exclusively on intertidal habitats. Their main food supply was two species of Eelgrass Zostera noltii and Zostera angustifolia. Although abundant when the birds arrived in September, this Zostera was rapidly depleted during the period October‐December. Brent Goose food intake rate declined with the decreasing food supply, and the birds responded by extending the time that they spent feeding. When it was no longer possible to extend the time spent feeding (i.e. they were feeding for all of the time that the food supply was available to them), they moved away from the site. The geese fed extensively at night in order to achieve their daily feeding requirements, especially later in the season. Conversion of daily food intake to energetic intake suggested that there may have been an energetic trigger acting: the geese left the site when they were unable to satisfy their basic energy demand. No evidence was found for direct interference competition between Brent Geese and the other grazer in the system, Wigeon Anas penelope: the two species showed no spatial segregation in their feeding areas at the scale investigated nor any temporal avoidance of each other.

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