Researchers have recorded the first direct evidence that birds consider the notion of camouflage when they choose colored materials for their nests.
A team from the University of St. Andrews wallpapered male zebra finch cages in different colors. Then they filmed the birds building their nests, giving them paper strip choices for nest material in two different colors.
The scientists observed that the finches largely chose paper strips for their nest that were a match with the paper covering the walls of their cages. This told them that birds will actively seek to match a nest's colors with those of its surroundings, and that what often looks like coincidental camouflage may indeed be a deliberate choice.
One interesting curve ball the finches threw at the researchers was to sometimes choose a small proportion of paper strips for their nests that was a mismatch with the wallpaper. The scientists think this means birds sometimes use a tactic called disruptive camouflage, wherein bits of clashing color break up the outline of the nest and make it look less like a bird lives there.
Prior evidence abounds for the idea that birds will move a nest elsewhere if predators lurk too close by, but the St. Andrews team asserts it has shown that birds may also try in more subtle ways to avoid predators.
"Like us (birds) don't choose just any colored material to build their homes; they avoid colors that would clash with their surroundings. Knowing this gives us a better idea of how birds may actively reduce the chances of predators finding their nests," said the report's author, Dr. Ida Bailey.
The team's work has just been published in the ornithological journal The AUK.