The spur-winged goose (Plectropterus gambensis) is a large, Sub-Saharan African waterbird in the family Anatidae, which includes geese and shelducks. However, P. gambensis developed unique environmental adaptations, which resulted in the evolution of several anatomical features that are not shared with other anatids; thus, the species has been classified one step further into its own subfamily, the Plectropterinae.
Description
left|thumb|[[De Hoop Nature Reserve, South Africa]]
Adults are long, and weigh an average of (rarely up to ), with ganders (males) being noticeably larger than the geese. The wingspan can range from . One source claims the average weight of males is around and the weight of females is around . However, 11 individuals that were banded in South Africa, were found to average only , with a range of . Another South African-based study found 58 males weighing an average of and measuring in total length; meanwhile, 34 females averaged in weight and in total length. Among standard measurements, the wing chord is , the bill is and the tarsus is .
Habitat
This species often occurs in open grasslands with lakes, seasonal pools, rivers, swamps and river deltas. Large inland rivers and lakes are perhaps most commonly inhabited, with saline lakes and upland areas generally being avoided, although the species can occur to an elevation of in eastern Africa. It is also absent from arid zones.
Ecology
The spur-winged goose is gregarious, generally meeting in small flocks that contain up to 50 birds. They occur around various African rivers, lakes and swamps. Varied sites may be used for post-breeding moulting, in which case large numbers of the geese may congregate. This common species feeds by grazing, but spends the middle part of the day resting by water. Its diet consists predominantly of plant matter such as the vegetative parts and seeds of grasses, sedges and aquatic plants, agricultural grains, fruit (e.g. figs) and tuberous crops, although it may occasionally supplement its diet with small fish or insects. Dispersal may occur in pursuit of feeding opportunities outside of the breeding season.