3D-Printed Eggs Fool Birds into Caring for Imposters (VIDEO)

3D printing has been moving forward by leaps and bounds and now, scientists have used it to create something a bit unusual: artificial eggs. Researchers have printed the eggs in order to test how birds identify and reject the eggs that invading "brood parasites" sometimes sneak into their nests.

Brood parasites are birds that don't build nests of their own. Instead, they slip their eggs into the nests of other species. Then, the parents may raise the invading chicks at even the expense of their own. In some species, this has led to a sort of evolutionary arms race in which host parents get better and better at identifying and rejecting eggs while brood parasites have become more adept at mimicking the eggs of their host species.

In order to study this phenomenon, researchers have long been creating artificial eggs and adding them to nests. The problem with this, though, is making convincing, uniform artificial eggs out of traditional materials. This, unfortunately, is surprisingly difficult and fake eggs can be time-consuming to make. That's why researchers turned to 3D printers.

In this latest study, the researchers created 3D printed eggs that were then painted to match either the beige of real cowbird eggs of blue-green of host American robins. The 3D printed eggs were then placed in robin nests which were then monitored for six days to see how the parents reacted.

The researchers found that the robins accepted 100 percent of the blue-green eggs but rejected 79 percent of the eggs painted to resemble those of cowbirds. This is similar to past studies using traditionally-produced plaster eggs. However, 3D printed eggs have the advantage of being less variable and more able to reproduce a desired size and shape.

"Hosts of brood parasites vary widely in how they respond to parasitic eggs, and this raises lots of cool questions about egg mimicry, the visual system of birds, the ability to count, cognitive rules about similarity, and the biomechanics of picking things up," said Don Dearborn, a brood parasitism expert who was not involved in the 3D printing study, in a news release. "For decades, tackling these questions has meant making your own fake eggs-something we all find to be slow, inexact and frustrating. This study uses 3D printing for a more nuanced and repeatable egg-making process, which in turn will allow more refined experiments on host-parasite coevolution."

The findings are published in the journal PeerJ.

Want to see the egg being printed for yourself? Check out the video below, courtesy of YouTube.

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