Would you have spotted this fiery-necked nightjar if you’d been a banded mongoose? © Jolyon Troscianko
Birdwatchers who wear khaki-coloured clothing in order to blend in with your surroundings, take note: camouflage really does work.
That’s what scientists have concluded after studying the predation rates on the eggs of ground-nesting birds in Zambia.
It seems obvious, doesn’t it? Sport plumage that looks the same as your environment, and you are less likely to be seen. Or lay eggs that perfectly match the background in which they are sitting, and they are less likely to be eaten.
But until now, it’s never actually been demonstrated.
So scientists from the Universities of Exeter and Cambridge found ground-nesting nightjars, plovers and coursers in Zambia and recorded egg predation rates over the period in which they were incubating.
Crucially, they used specially-calibrated digital cameras that allowed them to view the birds and the eggs as predators such as banded mongooses, birds and vervet monkeys might see them.
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They found that for those species – such as plovers and coursers – that flee the nest when predators come near, eggs were less likely to be taken if they matched their background more closely.
With nightjars – which remain sitting over their eggs when trouble looms – it was the appearance of the adult that dictated whether they were able to hatch them.
“We used a number of methods to quantify how close the eggs or adult birds were to the colour, pattern and luminance of their backgrounds,” said lead researcher Dr Jolyon Troscianko of Exeter’s Centre for Ecology and Conservation. “We expected colour to be important, but our survival analysis suggested pattern was more significant.”
Dr Martin Stevens, also of Exeter University, added: “Ours is the first study to directly show how the degree of camouflage an individual has, to the eyes of its predators, directly affects the likelihood of it being seen and eaten in the wild.”