The exploitation of beds of green algae by brent geese

Brent geese on the Norfolk coast occurred on beds of green algae (primarily Enteromorpha spp.) at low tide during autumn and early winter. Feeding was the main activity. Numbers of geese started to decline when the biomass of algae had fallen to c. 5 g dry wt m ^-2, and the birds rarely occurred on the beds after the biomass had reached c. 1 g dry wt m ^-2 in late November. The biomass of ungrazed algae did not decline as rapidly, nor to as low a level as that of grazed algae during the winter, showing that grazing by geese was partly responsible for the earlier decline in this food source.