Camouflaged or wildly colourful? NZ species prefer low profile

Animals can use bright colours or camouflage to deter predators. In a global study, New Zealand creatures stood out for not standing out – camouflage was de rigueur.

Across six continents, scientists used lepidoptera – butterflies and moths – to investigate the split between animals decorated with warning colours (which can signal `don’t eat me, I’m toxic’ or ‘I taste bad’) and those without.

It turned out New Zealand’s field site in the Waitakere Ranges had the smallest ratio of warning-colour species (3) to camouflage species (49) behind sites in Argentina, Australia, Brazil, Cameroon, Canada, Colombia, Costa Rica, Czech Republic, Finland, India, Kenya, Netherlands, South Korea, US, and Wales.
 

What gives with the penchant for the low profile?

Associate Professor Kristal Cain from Waipapa Taumata Rau, University of Auckland, who led the research in Aotearoa, says the explanation may be “the multitude of insectivorous birds, since a camouflage strategy is favoured when predator intensity is high.”

The high number of cryptic colouration species – the scientists’ term for creatures who camouflage – “may also be due to camouflaged prey faring better in dense, dark environments, like the North Island study site, than in bright, open forests,” she says.
 

In the study just published in Science, more than 15,000 paper “moths” in three different colours – a classic warning pattern of orange and black, a dull brown, and an unusual bright blue and black – were attached to trees at field sites.

Scientists observed attacks by birds on the mock prey.

In New Zealand, the research was carried out in November 2021.

The project, led by academics from the University of Melbourne and Swansea University, aimed to advance our understanding of why some animals evolved to issue warnings via their bright colours while others use camouflage.
 

“For a long time, scientists have wondered why some animals use one defence over the other – and the answer turns out to be complicated,” says lead author Dr William Allen.

“The predator community, prey community and habitat are all influential. This helps explain why we see camouflaged and warning-coloured animals all over the world.”

The findings support the idea that predators competing intensely for food are more likely to risk attacking prey that looks dangerous or distasteful. Hence, camouflage works better to avoid being eaten in areas with lots of predators.
 

But being cryptic didn’t always work.

In bright environments, camouflaged prey became more visible and suffered more attacks than prey with classic warning colours. In places where cryptic prey was abundant, hiding became less effective, as predators became more skilled at detection.