White swans need miracle

Press, 29 September 1988, Page 31

White swans need miracle

DERRICK ROONEY:

story and photographs

New Zealand’s last major population of its largest, and arguably most charismatic, introduced bird appears to be in the final stages of decline and it seems unlikely that anything can, or will, be done to save it.

Only about 20 of the birds — the white, or mute, swan — were counted on Lake Ellesmere by Department of Conservation staff in the regular April survey of bird populations on the lake. This means that the population of the bird, which peaked at about 400 in the mid-19605, has probably declined by one-third in the last year. The Wahine storm

of 1968 precipitated the decline of the swan and although there was a slight recovery about 1974 the trend has been downwards for 20 years. "The mute swan,” says Dr Ken Hughey, of the Department of Conservation, “is in real, real strife. This is very sad, because it is a fine bird.” / The white swan was introduced to New Zealand in the

1860 s by the Governor, Sir George Grey, and was released on Lake Ellesmere in the 1870 s by the North Canterbury Acclimatisation Society. Lake Ellesmere has always been its main breeding area in New Zealand and although a few of the birds — mostly of Ellesmere origin — are in private wildfowl parks and other institutions, there are no major breed-

ing populations outside the Ellesmere area. Since 1968 the Ellesmere swan have been notably unsuccessful breeders and fewer than 10

cygnets are known to have hatched in the last 10 years. The remaining birds are gradually dying of old age. “We would very much like to

do something to save these birds from extinction in New Zealand,” says Dr Hughey, “but our resources are limited, and the swan is not a native bird. It has to take a lower priority than endangered indigenous birds.” Dr Hughey attributes the decline of the white swan to several factors but the main ones are infertility and deterioration of the birds’ food supply — as a

consequence of. a general deterioration in the condition of the lake. A third factor in the birds’ decline is inbreeding. White swan favour open lake water with a freshwater influence (such as the mouths of streams and lagoons) and raupo swampland — two of the habitats most threatened by agricultural and other pollution. They nest only in the raupo beds, mostly in

the Harts Creek area, which is a wildlife reserve where shooting is prohibited. Since 1968 both the breeding rate and the survival rate of cygnets have been low. Humans are another factor. The birds are absolutely protected, but in spite of this two were shot last season. If the . decline continues at the present rate — and it seems that only a miracle can reverse it — there will be no white swan left by the mid-19905. "The population,” says Dr Hughey, “is now so small that every single death, from whatever cause, is of major concern.”