A new paper published in Current Biology has shown that female quail “know” what the patterning on their eggs is going to be before they lay them.
The study has also revealed that this helps the birds decide where they should lay their eggs and that – when given a choice – they most often choose the laying location that offers their eggs the best camouflage.
They do this by selecting one of two camouflaging techniques: ‘background matching’ or ‘disruptive colouration.’
Lead author of the study, Dr P. George Lovell from the University of Abertay Dundee, explains why this is so interesting:
“Quail eggs vary hugely in appearance: some are pale with a few spots and speckles, while others are covered in large, dark brown splotches.
“The eggs are laid on the ground or in open grassland, so the threat from visual predators is very high. This means that being well camouflaged is vital if the eggs are to survive, and our study showed that the quail try to maximise egg camouflage by choosing locations appropriate to their own individual egg patterning.
“When we gave the birds a choice of where they could lay their eggs, they most often chose to lay them in the location that offered them the best camouflage – or, in other words, that made them most difficult to see.
“We also found that the camouflaging technique they selected differed, depending upon how much speckling their eggs were going to have: when they laid an egg with just a few spots or speckles, they used a technique known as ‘background matching’, where they chose somewhere that matched the background colour of the egg.
“But when they laid an egg with more than 30 per cent speckling, they used a technique called ‘disruptive colouration’, where they chose a location that was more similar in colour to the speckling, rather than the background colour.
“These techniques work in different ways: disruptive colouration breaks up the outline of the egg so that it’s more difficult to see which edges belong to the egg outline, while background matching works by making the egg’s outline harder to see.”
When the research team conducted the study, they had no idea about the extent to which the birds “knew” their own egg patterning and were able to make decisions about camouflage based upon that knowledge.
Until now, there has been very little evidence in any species that animals are aware of their individual patterning and that they choose an appropriate environment within which to hide.
However, this study has shown that it is actually the patterning on the egg that informs the quail’s decision about where to lay it.
Dr Lovell continues:
“From an evolutionary perspective, what you can and cannot see is of the utmost importance – predators need to be good at detecting their prey in order to survive, but the prey also need to be good at hiding their eggs, if they want to avoid predation.
“So the whole point of camouflage is to disrupt the visual perception of the predator, as this will enhance the survival of the species being hunted, and it seems that, when it comes to camouflage, quail really know what they’re doing.
“Although we don’t yet know for certain what the mechanism for this is, it’s likely that it is something that they learn: in the wild, first time breeders across many species are often unsuccessful, so the ability to choose an appropriately camouflaging nesting position is probably based upon seeing what their first egg looked like.”
Notes to Editors:
The trial involved 16 female Japanese quail, and a total of 179 eggs were collected over a two week period.
During the trial, the quail were each given a choice of four different coloured sands on which they could lay their eggs.
The eggs were then photographed in the location on which they were laid. This was sometimes in the gaps between the sands – it really depended on where the quail felt its egg would be most difficult to see.
The other locations were also photographed, and the research team developed a model predator that attempted to find the outline of the egg in each of the four locations.
When they compared the results, they found that each time, out of all the options the quail could have chosen, they most often chose the location that offered their egg the best camouflage.