Female Japanese quail (Coturnix japonica) lay their eggs on the ground where they can make tempting meals for rodents, snakes, and deer. But as new research published in the journal Current Biology shows, these mothers choose areas on the ground that best match their eggs' patterns.
Quail eggs have a pale yellow or beige background, but their appearance varies because of the amount of darker splotching—meaning there is no one-size-fits-all area for egg laying. Instead, researchers suggest that female quail "know" what their own eggs look like and will lay their eggs where they will be best camouflaged.
The birds seem to use two types of camouflage, said the study's lead author P. George Lovell, of the University of St. Andrews in Scotland—background matching and disruptive coloration.
Background matching is just what it sounds like; the pattern of an object to be camouflaged matches the pattern of its background, as when a peppered moth disappears on a tree branch.
Disruptive coloration, seen in zebras, works by visually breaking up the edges of the object being camouflaged. This "makes the outline harder to find because the contrasting edges may be mistaken for parts of the background," said Lovell. (Related: "Fish Mimics Mimic Octopus That Mimics Fish.")
The quail seem to use both techniques. Lovell and his collaborators offered the birds four different colors of sandy surfaces on which to lay their eggs. Birds whose eggs had more splotching tended to lay their eggs on the background that matched the splotches—employing disruptive camouflage.
However, birds whose eggs had smaller amounts of markings tended to choose surfaces that matched the background color of their eggs, perhaps because the lack of splotching on the edges of the egg would make disruptive camouflage difficult.
"Quail aren't any more clever than any other species," said Lovell, and all species make decisions as they try to successfully reproduce. "What we have found here is how finely scaled these decisions might be." (See pictures of cuttlefish that can mimic photos.)