Use of grassland and field selection by brent geese Branta bernicla.
Around Scolt Head Island, N. Norfolk 43.7%, 57.7% and 65.5% of the cumulative total number of observations of brent geese (Branta b. bernicla) were made on grass fields during 1986-87, 1987-88 and 1988-89, resp. In the 1st year more time was spent on arable fields compared with the following years. On av., 74% of the day (dawn-dusk) was spent on grass or arable fields during Jan.-Mar. The time of arrival of geese on the fields in the morning was related to the state of the tide. Arrival was later if high tide occurred around dawn and earlier if low tide occurred around dawn. The geese left grass fields 11 ± 22 min before sunset to roost. Individual geese visited 3.9 ± 1.6 fields (mean size, 5 ha) day-1 spending 1.7 h in each. Foraging was the main activity, comprising 71% of the time-activity budget. Daytime flights between the roost and grassland feeding sites were 8.2 ± 2.4 km long. Home ranges were 6.1 ± 2.1 km2. Grazing intensity (estimated from dropping densities) averaged 42.8 droppings/m2 for 3 of the most intensively used fields, representing 2.4 h of grazing/m2 indicating 500 m2 would support 1 goose from Nov. to mid Mar. Fields with a high percentage of live grass were selected by geese, perhaps on the basis of their colour. Once selected, those fields with the shortest grass (approx. 5 cm) and fewest thistles were more intensively used. The use of suitably managed grass swards as alternative feeding areas to alleviate grazing on cereals is recommended.