Camouflage theories in question

WELLINGTON: Australian and New Zealand biologists have discredited an old theory that birds of a duller feather are safer from predators.

University of Auckland researchers looked at the fairy wren, which can be found with both colourful and duller, brown plumage, and made 3D printed plastic versions of the birds to see which would be attacked the most.

Cameras and field observation were used to monitor the rate at which predators attacked the differently coloured bird models.

Of 2511 model fairy wrens, 331 showed signs of an attack and the attack rate was similar for both conspicuously coloured models and dull brown coloured birds.

University of Auckland School of Biological Sciences lead researcher Dr Kristal Cain said the findings went against previous research.

‘‘We found the most brightly coloured females [in fairy wrens] are found where vegetation is really dense, where visibility is really limited, so the conclusion from that is the probable thing that’s driving the difference of colour is that it’s safer.’’

Dr Cain said the research was to show it made sense for birds in an open habitat to be much more camouflaged.

To test this, the 3D printed birds were put in eight places around Australia in both dense and open habitats.

Dr Cain said gender seemed to play more of a role in the likelihood of an attack.

‘‘What we think is going on is being brightly coloured is more dangerous for females, because they need a lot of energy to lay eggs and take care of their offspring, more so than the males.

‘‘Male fairy wrens spend a lot of time standing around and looking. They’re really vigilant, whereas the females don’t have time for that; whenever they’re around they’re foraging and much more vulnerable.’’ — RNZ