Breeding, Feeding and Status of the Torres Strait Pigeon at Low Isles, North-eastern Queensland

Abstract

The feeding and breeding biology of a colony of the migratory Torres Strait Pigeon Ducula spilorrhoa, comprising 20,000 to 25,000 birds, was studied at Low Isles, north-eastern Queensland, briefly at the end of the 1970-71 breeding season but more intensively in the 1971-72 and 1972-73 seasons. Like most islands favoured by these birds, Low Isles has mangroves. The mangrove trees provide nesting sites but food is obtained from the mainland rainforest to and from which the buds fly each day.

A monthly record of diet, analysed from droppings, is presented. There were differences between the diets in the 1971-72 and 1972-73 breeding seasons, which could be related to the availability of fruit m the forest on the mainland.

The nest is large for a pigeon and is the centre of a feebly defended territory of a mated pair. Clutch size is one. Incubation and fledging periods are about twenty-eight days each. Hatching success was ninety-one per cent.

Density of nests was correlated with the density of the vegetation and was different each year. The years of high nesting density corresponded with years of good fruit production particularly by species of Lauraceae; low density occurred when fruit production was poor, suggesting that food may be a regulat- ing factor for the population. Direct disturbance by man has probably caused the bird's decline this century.