Spotted Eggs Are Hard To Spot.

quail eggs

A composite shot of quail eggs on coloured substrates.Credit Lovell et al.

Hiding a valued item from thieving layabouts is not the exclusive concern of co-habiting women with a penchant for Galaxy bars. In nature too, plunderers are everywhere, from bears stealing honey to ants stealing slaves; the animal kingdom is full of kleptomaniacal jerks.

To a ground nesting quail, its eggs are the metaphorical Galaxy bar. The eggs are a valuable source of free protein to opportunistic predators and quail must make efforts to conceal them from these marauders. Camouflage is the quail’s counter-measure of choice; the maculation (blotched patterning) on the eggs can make them quite difficult to spot against the right background. However, the degree of egg maculation can vary significantly between individual birds so that the “right background” for one quail isn’t necessarily the right background for another. This doesn’t appear to be a problem though as research, performed by Dr. P.G. Lovell’s team at the University of St. Andrews, has revealed that individual quail can tell which substrates best conceal their own eggs.

Japanese Quail

Japanese Quail (Coturnix japonica). Credit Lovell et al.

The study, published in Current Biology, has shown that given a choice of coloured substrates on which to lay their eggs, quail consistently chose the substrate that resulted in the highest degree of camouflage from a model predator.
The camouflage is achieved through a combination of background matching and disruptive colouration. Background matching, as the name suggests, is simply the process of hiding against a backdrop that is of a similar colour and/or texture. Disruptive colouration serves to break a perceived outline, making an object’s edges difficult to detect.

Egg close up

Egg close-up showing detail of speckling. Credit Lovell et al. (If you are having trouble viewing the .gif try clicking on it)

A key aspect of camouflage research is to understand how factors such as shading contribute to a predator’s capacity to perceive an object. For example, we intuitively expect objects under sunlight to be well lit on top and darker underneath. Countershading, such as that seen in deer, appears to be an effort to disrupt this perceptive tool.

Dr. Lovell plans to further explore the difference between camouflage strategies and the perceptive mechanisms each aims to exploit. Asked about this upcoming research he said “In essence we’re hoping to explore the difference (if any) between background matching camouflage, where you simply try and hide yourself by having the same colour and texture, and counter-shading which may additionally be concerned with concealing 3D shape.”

The quail’s apparent awareness of its eggs’ camouflagic properties is an interesting divergence from the assumption that camouflage is, for the most part, a passive act. This revelation certainly raises interesting questions regarding concealment efforts in other species. In many instances of apparently deliberate hiding, it can be difficult to rule out the possibility that the concealment efforts are merely side effects of an unrelated behavioural response. Chameleons ,for example, utilise their colour changing capabilities in behaviours such as signaling and thermoregulation.

Liu Bolin

This guy knows what I’m talking about. © Courtesy of Liu Bolin / Galerie Paris-Beijing

Whatever the behavioural motivation behind the quail’s egg laying behaviour, they’ve certainly made it difficult for predators to poach their eggs (See what I did there?).

Source: Lovell et al. 2013 “Egg-laying Substrate Selection for Optimal Camouflage by Quail.”Current Biology (2013)
Images: Sources as per captions.

Many thanks to Dr. P.G. Lovell for his contribution to this post.

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