Grass is the basic diet for both wild and domesticated geese. The wild birds have greater choice of plant species, and can migrate to follow the growing season for the best bite, but their farm cousins are confined to the same patch. So it is essential, for the health of the domesticated birds, that their pasture is well managed and they have supplementary food.
Not only do healthy geese need grass in their diet, but there will be no profit if commercial geese are reared solely from bags, for they can soon eat more than they are actually worth. Pasture for rearing and maintenance is needed to make any profit from geese for the Christmas market because they will then be up to 30 weeks old, in contrast to the grain and soya-fed broiler chickens of just six weeks of age. So, now is the time to think of managing grass quality for the breeding birds in 2010 and ensuring that clean grass is available for the goslings in spring.
Wild geese Species of wild geese show a lot of variation in the size and shape of their bill, because of adaptation to the varying foods they eat. The wild swan goose has a large, long, heavy bill which is not suited to short pecks at a tight sward.
The lamellae at the side of the bill, developed for cutting action, are not as well developed as in the greylag. So the swan goose chooses larger-leafed vegetation and roots. Even the domesticated breeds developed from the swan goose – the Chinese and African – have slightly differing feeding habits from the greylag derivatives.
Many species have an “all-purpose” bill which can be used for grubbing out roots, grazing pasture or stripping seeds from grasses. But some of the smaller geese such as the Red-breasted and Lesser White-front are more specialised. They have short beaks for precision pecking, and they like short sward. Peck rates have been recorded at up to 180 per minute!
The habitat and diet of wild geese, especially within Europe, has probably changed over the centuries as more and more land had been cleared from forest, marsh and fen.
Glasswort mudflats, tidal saltmarsh grasses, and fen vegetation may have been more important before the marshland habitat was drained and agricultural grassland became more widely available. As the grazing farm animals maintained a good turf, so the geese moved onto this agricultural land.
Farmers’ winter ryegrass and wheat are crops prized by geese which descend in October and stay until April. Thus management of crop land, and even compensation payments, may take place where goose conservation and farm livelihood are in conflict.
The actual distribution of geese has probably remained the same, because they are conservative in their habits. They choose traditional places of safety overnight on estuarine sandbanks or inland lakes where the density of the birds in the flock is very high. Depending on the species, these flocks will fly out to do most of their feeding within two to five kilometres of the overnight roost.
Geese are very inefficient feeders. They cannot make use of the cellulose in the same way as cattle and sheep. They need to gather food over a large part of the day. Even in winter, when daylight hours are short, they have to spend seven to eight hours eating. This short grazing time is the reason why birds need to put on as much weight as possible during the autumn in order to reach a peak weight in November.
The energy reserves they build up will get them through the harsh winter months, on poor-quality resources, before new high-nutrient vegetation growth starts again in spring.
As the growing season for grass starts again in the southern over-wintering regions, geese first take advantage of this new green bite then leave, sometimes using staging posts before reaching the breeding grounds.
For example, Barnacle geese at Caerlaverock leave the Solway from mid April onwards and may use locations off Norway and southern Spitzbergen before reaching the nesting sites on Bear Island, Svalbard, 14-31 days later at the end of May. Wild geese therefore utilise the onset of the growing season that changes with latitude. As they migrate from their winter roosting locations back to their nesting sites further north, they get a sequence of “first bites” where the shoots of grass offer top protein value, at several locations.
They are building up protein and nutrient reserves essential for the production of high quality eggs. In contrast, on their return journey to the Solway in September/October, the flight can be made in as little as 48 hours when there is clearly no advantage in staging the food supply.