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hen and ducklings

Image by cod_gabriel

When I was young and living on a small farm in the Adelaide Hills, we used to raise ducklings under chickens. The hens were more inclined to sit and warm the eggs, and once hatched were better at protecting their young from rats. So we took duck eggs, placed them under brooding hens, and everything was cheery.

Those hens loved them little ducks, at least, they looked after them just as well as they did their own chicks. They’d go out foraging together, chattering away in their different tongues at a handful of scattered grain. But there was one place where their differences became obvious. The pond.

At the first sight of water, the ducklings would be in and swimming, having a great time duck-diving underwater and eating duckweed. Meanwhile, mother hen would be going absolutely spare! You could almost hear the concerned clucks saying “now get out of that water at once! Don’t you know you can’t swim? Oh heavens, what have I done to deserve such unruly children?”

What she’d done, somewhat unintentionally, was to be a cross-foster mother. A species which raises children of another species.

Peahen and guineafowl chicks

Image by Chicago Zoological Society

Chicago’s Brookfield Zoo recently raised two clutches of guineafowl chicks with peahen mothers. The parents protected their brood from hawks, and showed them the ropes of living free-range in the zoo – such as how to avoid pedestrians.

From the press release:

“‘Zoogoers may not notice anything unusual between the moms and chicks, but there are definitely differences and several barriers that they needed to overcome, including language and behaviors,’ said Tim Snyder, curator of birds for the Chicago Zoological Society, which manages Brookfield Zoo. ‘The first two weeks were a little precarious because the chicks needed to learn what the peahens’ vocalization meant and adapt to different behaviors that are not instinctual to them.’

“For instance, Guineafowl chicks naturally scatter and hide when frightened or threatened, while peachicks run toward their mother. Additionally, Guineafowl moms and chicks move as a group and help care for each others’ young, which is the opposite of independent peafowl.”

Black Robin on Rangatira Island

Image by Frances Schmechel

Cross-fostering for conservation helped bring Black Robins from the brink of extinction. In 1980, only five survived in the wild on Little Mangere island in New Zealand, including a just one fertile female called Old Blue.

Each Spring, the first clutch of eggs was raised under a Chatham Island tit, giving Old Blue time to breed twice in the season.

Bit by bit the population has crawled back and is now a relatively comfortable 250 individuals. The fostering program has been used as a model for other endangered bird species.