The Straw-necked Ibis Threskiornis spinicollis gets its name for its lower throat feathers. These are kept all year round, which is unusual for water birds, as their primary function is being moved as part of their breeding display. Most other wading birds that have special feathers like this — such as egrets, herons,and spoonbills — grow them only in the breeding season and them lose them afterwards.
Straw-necked ibises come and go around Goulburn and the surrounding country. Unlike many water birds that have very firm requirements for water, straw-necked ibises can hunt their prey not merely in shallows but in moist grass, even if it is a mowed football field. They like to be in areas with abundant insects (especially grasshoppers), frogs or mice, for they have a prodigious appetite.
Years ago I happened to be visiting a friend in Canowindra and the night road there was filled with small animals hopping across it. I thought they might have been frogs for their size and my speed. They quickly disappeared when I stopped to look. My friends, who were seasoned travellers with this sort of thing, informed me that I had just brought news of the beginning of a new mouse plague. Sure enough, a week later there were mice everywhere. Every piece of tin lying in the paddock was wall-to-wall mice underneath; every shed ran with liquid hordes around the hay bales; every bush and grass tussock shook constantly with mice; every night 10 break-back mouse traps were set in each room of the house and every morning they would be full, sometimes with more than one mouse per trap. The cats and dogs became sick of the sight of mice after one or two days and the local pigeon fanciers had apparently shot all the birds of prey for miles around. There was nothing anyone could do but wait for the plague to finish. There was a paddock of lush grass next to my friends’ house that seethed with mice. One day a flock of straw-necked ibises came in and lined up across the paddock and just kept eating. They completely relieved the 10 acre rectangle of its warm furry burden and were still ready for more, so moved off to the next paddock. Days later the rat plague came. That marked the end of the mice. A few days later the rats were gone too.
Straw-necked ibises will do the same thing for locusts out west: eating the hordes of big insects until there are few left. They may not stop plagues, but they very effectively reduce them. This ibis is highly nomadic and has been since early settlement regarded by farmers as the one of the most useful birds in the country. If you city folks think you don’t need them, then just reflect on the greatly increased cost of your bread, fruit and vegetables without visits from friendly straw-necks. No wonder the ancient Egyptians worshipped ibis.
This species has an iridescent black coat, as can be seen in the two topmost photos on this page. In the sunlight these dark feathers can reflect green, blue, purple or pink as they walk around fields and wetlands. Although it is difficult to tell the sexes apart, the female has a noticeably shorter bill. Straw-necked ibis are easy-going birds and tolerate other species readily. They are fond of the company of others of their own species and often form large flocks as they move around the country. As they fly they often form large formations either in V-shapes or in a long writhing tail snake shape, or skein.
Young birds lack the straw feathers at the base of the neck. As can be seen in the accompanying photo, they also lack the full black head of the adult. As they mature their head darkens and during their first breeding season they will develop their distinctive neck feathers.
Their long bills have a scimitar-like curve. This curve acts to strengthen the bill, much like the arch does for a building or bridge. In this way their bill acts both as a set of pincers, capable of detecting and picking up small and large prey alike, but also enables them to poke it long distances into mud or moist soil to extract worms, grubs, burrowing frogs and small animals.
Straw-necked ibis rest in bare trees during the day (another reason not to chop them all down), but roost in leafy trees at night. The trees they choose to breed in are different again: they must be over water, so flooding means a chance for the ibis to breed. They form a raft of loose sticks and nest in colonies in southern Australia that can contain up to 60,000 birds at a time. Well away from towns and in inland areas it is by far the most numerous ibis in Australia.