A quail egg is like a protein-filled, free lunch, waiting on the ground to be spotted—and devoured—by a predator. But the Japanese quail (Coturnix japonica) seems to have mastered an impressive level of camouflage-manipulating behavior to keep her eggs off the menu.
Female Japanese quails tend to lay distinctive eggs that are specific to each individual quail. Some of the birds lay eggs that are deep gold and half covered with dark brown splotches; others' eggs are a delicate pale yellow with just a smattering of gray spots. A new study suggests that the female selects a nesting area that is the best camouflage for her specific egg appearance before it is laid. The findings were published online January 17 in Current Biology.
Camouflage tactics in the animal world often take advantage of either blending—in which an animal resembles elements in their environment, such as a walking stick insect, for example—or disruptive coloration—in which a pattern on the animal makes it difficult to spot the animal's outline, as in the case of the leopard. These Japanese quails take advantage of both for their eggs, depending on the situation, the scientists found.
Led by George Lovell, of the University of St. Andrews in the U.K., the team presented female Japanese quails with the choice of four different backgrounds for laying their eggs. "When given a choice, birds consistently selected laying substrates that made visual detection of their egg outline most challenging," the researchers noted in their paper.
Perhaps even more impressive, "the maximization seems specific to individual birds," Lovell said in a prepared statement. A female, for example, that tends to lay eggs with few spots on them selected surfaces that most closely matched the overall color of the egg, utilizing a background-matching tactic. A female, however, that laid eggs largely covered in dark spots will usually chose a dark background to take advantage of disruptive coloration. Because females tend to lay similarly patterned eggs over time, the findings suggest that the birds are choosing a laying location rather than controlling the appearance of their eggs based on their environs.
"Our results show that quail 'know' their individual egg patterning and seek out a nest position that provides most effective camouflage for their individual phenotype," Lovell and his colleagues noted in their paper.
Understanding the effectiveness of this strategy in the wild will take more work, and other factors—such as available material and environmental surroundings—might also impact the birds' choice of nest site outside of the lab.
But the findings present an interesting suggestion that these quails strategically select a laying site in advance based on the appearance of their eggs.
"Animals make choices based upon their knowledge of the environment and their own phenotype to maximize their ability to reproduce and survive," Lovell said in a prepared statement. And the example of the quails' egg-laying behaviors "should encourage camouflage to be seen not simply as a function of the appearance of an organism, but as a function of both appearance and behavioral traits," he and his colleagues noted in their paper.
Some animals, such as the octopus, make the behavioral element of camouflage seem obvious (as they, themselves, can shift their appearance to match their environment). But for animals that are not so in control of the way they—or their eggs—look, selecting the best location to match their appearance seems to be an impressive adaptive ability.