Featured Research

from universities, journals, and other organizations

Caterpillars aren't so bird-brained after all: Clever behavioral strategies help them outwit predators

Date:
April 5, 2011
Source:
University of Exeter
Summary:
Caterpillars that masquerade as twigs to avoid becoming a bird's dinner are actually using clever behavioral strategies to outwit their predators, according to a new study.

Caterpillars that masquerade as twigs to avoid becoming a bird's dinner are actually using clever behavioural strategies to outwit their predators, according to a new study.

Researchers at the universities of Exeter, Liverpool, Liverpool Hope and Glasgow have shown that when it comes to the art of camouflage, things are never quite the way they seem.

The study, published online April 4 in the journal Proceedings of the National Academy of Sciences (PNAS), reveals that twig-mimicking caterpillars choose their location to maximise their chances of fooling their predators into thinking they are twigs.

Using domestic chicks (gallus gallus domesticus) as predators of twig mimicking Early Thorn moth caterpillars (selenia dentaria), research showed that caterpillars are more likely to fool birds when twigs are common.

In order to exploit birds' behaviour, caterpillars position themselves in locations where twigs are in abundance during the day -- even if they're not good locations for feeding.

At night, when the predators cannot hunt by sight, the caterpillars go to rich feeding grounds -- regardless of twig abundance.

Dr John Skelhorn, a lecturer in animal behaviour at the University of Exeter and lead author of the study, said: "The caterpillars are not just blindly mimicking inedible objects in the environment and hoping for the best, they are actually using complex habitat-selection strategies which exploit predators' hunting behaviour.

"In this study, we observed that the chicks were less likely to search for masquerading prey when the object they mimic, in this case twigs, is in abundance. It seems the low chances of finding prey and the amount of effort involved put them off.

"The caterpillars make the most of this by selecting habitats where twigs are common during the day, but then abandon them at night, when there are no visually-hunting predators around, in order to go in search of the best feeding grounds."

To come to this conclusion, the researchers carried out a number of different trials using the chicks and caterpillars. In the trials, the team found that chicks exposed to situations where they had little success in checking twigs became less likely to look in the first place. When prey was hidden amongst a higher number of twigs, it also took the chicks much longer to find the caterpillars.

The research then looked at the behaviour of the caterpillars, placing them in an environment where they could choose between two branches -- one with few twigs but plenty of food, and another with more twigs but no food.

Caterpillars showed a strong preference for the branch with lots of twigs, offering the best protection from their predators, during the daylight. At night, they opted for the food-rich branch.

Dr Skelhorn added: "This research shows that there are costs associated with masquerading as an inedible object. Caterpillars aren't free to go where they want and have to select their locations very carefully. The benefit of masquerade is also determined by how many twigs are around, and how many other individuals are masquerading as twigs in the local environment.

"If there are too many masqueraders in one area, predators will learn this and be highly motivated to search for them. It really relies on there being not too many individuals trying to pull the same trick.

"The findings could inform conservation efforts for endangered masquerading species, such as the leafy sea dragon, as it is clear that the inedible objects these creatures resemble must remain abundant in order to protect them from predators."

This research follows up on an earlier study involving Dr Skelhorn which showed predators mistake prey that mimic inedible objects in their local environment, such as twigs or stones, for the object that they resemble.

This work was supported by National Environment Research Council Grant (NERC) NE/E016626/1.


Story Source:

The above story is based on materials provided by University of Exeter. Note: Materials may be edited for content and length.


Journal Reference:

  1. John Skelhorn, Hannah M. Rowland, Jon Delf, Michael P. Speed, Graeme D. Ruxton. Density-dependent predation influences the evolution and behavior of masquerading prey. Proceedings of the National Academy of Sciences, 2011; DOI: 10.1073/pnas.1014629108

Cite This Page:

University of Exeter. "Caterpillars aren't so bird-brained after all: Clever behavioral strategies help them outwit predators." ScienceDaily. ScienceDaily, 5 April 2011. <www.sciencedaily.com/releases/2011/04/110404151338.htm>.
University of Exeter. (2011, April 5). Caterpillars aren't so bird-brained after all: Clever behavioral strategies help them outwit predators. ScienceDaily. Retrieved September 22, 2014 from www.sciencedaily.com/releases/2011/04/110404151338.htm
University of Exeter. "Caterpillars aren't so bird-brained after all: Clever behavioral strategies help them outwit predators." ScienceDaily. www.sciencedaily.com/releases/2011/04/110404151338.htm (accessed September 22, 2014).

Share This



More Plants & Animals News

Monday, September 22, 2014

Featured Research

from universities, journals, and other organizations


Featured Videos

from AP, Reuters, AFP, and other news services

Cat Lovers Flock to Los Angeles

Cat Lovers Flock to Los Angeles

AFP (Sep. 22, 2014) The best funny internet cat videos are honoured at LA's Feline Film Festival. Duration: 00:56 Video provided by AFP
Powered by NewsLook.com
Washed-Up 'Alien Hairballs' Are Actually Algae

Washed-Up 'Alien Hairballs' Are Actually Algae

Newsy (Sep. 22, 2014) Green balls of algae washed up on Sydney, Australia's Dee Why Beach. Video provided by Newsy
Powered by NewsLook.com
Raw: San Diego Zoo Welcomes Cheetah Cubs

Raw: San Diego Zoo Welcomes Cheetah Cubs

AP (Sep. 20, 2014) The San Diego Zoo has welcomed two Cheetah cubs to its Safari Park. The nearly three-week-old female cubs are being hand fed and are receiving around the clock care. (Sept. 20) Video provided by AP
Powered by NewsLook.com
Chocolate Museum Opens in Brussels

Chocolate Museum Opens in Brussels

AFP (Sep. 19, 2014) Considered a "national heritage" in Belgium, chocolate now has a new museum in Brussels. In a former chocolate factory, visitors to the permanent exhibition spaces, workshops and tastings can discover derivatives of the cocoa bean. Duration: 01:00 Video provided by AFP
Powered by NewsLook.com

Search ScienceDaily

Number of stories in archives: 140,361

Find with keyword(s):
Enter a keyword or phrase to search ScienceDaily for related topics and research stories.

Save/Print:
Share:

Breaking News:

Strange & Offbeat Stories


Plants & Animals

Earth & Climate

Fossils & Ruins

In Other News

... from NewsDaily.com

Science News

Health News

Environment News

Technology News



Save/Print:
Share:

Free Subscriptions


Get the latest science news with ScienceDaily's free email newsletters, updated daily and weekly. Or view hourly updated newsfeeds in your RSS reader:

Get Social & Mobile


Keep up to date with the latest news from ScienceDaily via social networks and mobile apps:

Have Feedback?


Tell us what you think of ScienceDaily -- we welcome both positive and negative comments. Have any problems using the site? Questions?
Mobile: iPhone Android Web
Follow: Facebook Twitter Google+
Subscribe: RSS Feeds Email Newsletters
Latest Headlines Health & Medicine Mind & Brain Space & Time Matter & Energy Computers & Math Plants & Animals Earth & Climate Fossils & Ruins