Featured Research

from universities, journals, and other organizations

Birds evolve 'signature' patterns to distinguish cuckoo eggs from their own

Date:
June 18, 2014
Source:
University of Cambridge
Summary:
For some birds, recognizing their own eggs can be a matter of life or death. In a new study, scientists have shown that many birds affected by the parasitic Common Cuckoo -- which lays its lethal offspring in other birds' nests -- have evolved distinctive patterns on their eggs in order to distinguish them from those laid by a cuckoo cheat.

The interactions between the Common Cuckoo and its hosts (like the Reed Warbler shown on the left, caring for a much larger cuckoo chick) provide a classic case of coevolution. To trick their hosts into accepting foreign eggs, cuckoos have evolved egg mimicry. Using a new pattern recognition tool, NATUREPATTERNMATCH, researchers show that host birds have evolved individual egg pattern signatures, which allow them to distinguish their own eggs from those of a cuckoo cheat. NATUREPATTERNMATCH extracts visual features, here represented by magenta vectors (centre). Three eggs each (represented in different rows) laid by three different Great Reed Warblers are shown here (right).
Credit: David Kjaer (left) and Mary Caswell Stoddard/Natural History Museum, UK (centre, right)

For some birds, recognising their own eggs can be a matter of life or death. In a new study, scientists have shown that many birds affected by the parasitic Common Cuckoo -- which lays its lethal offspring in other birds' nests -- have evolved distinctive patterns on their eggs in order to distinguish them from those laid by a cuckoo cheat.

The study reveals that these signature patterns provide a powerful defense against cuckoo trickery, helping host birds to reject cuckoo eggs before they hatch and destroy the host's own brood.

To determine how a bird brain might perceive and recognize complex pattern information, Dr. Mary Caswell Stoddard at Harvard University and Professor Rebecca Kilner and Dr. Christopher Town at the University of Cambridge developed a new computer vision tool, NaturePatternMatch. The tool extracts and compares recognizable features in visual scenes, recreating processes known to be important for recognition tasks in vertebrates.

"We harnessed the same computer technology used for diverse pattern recognition tasks, like face recognition and image stitching, to determine what visual features on a bird's eggs might be easily recognised," explained Stoddard.

Using the tool, the researchers studied the pigmentation patterns on hundreds of eggs laid by eight different bird species (hosts) targeted by the Common Cuckoo.

They discovered that some hosts, like the Brambling, have evolved highly recognisable egg patterns characterised by distinctive blotches and markings. By contrast, other hosts have failed to evolve recognisable egg patterns, instead laying eggs with few identifiable markings. Those hosts with the best egg pattern signatures, the researchers found, are those that have been subjected to the most intense cuckoo mimicry.

The Common Cuckoo and its hosts are locked in different stages of a co-evolutionary arms race. If a particular host species -- over evolutionary time -- develops the ability to reject foreign cuckoo eggs, the cuckoo improves its ability to lay eggs that closely match the color and patterning of those laid by its host.

"The ability of Common Cuckoos to mimic the appearance of many of their hosts' eggs has been known for centuries. The astonishing finding here is that hosts can fight back against cuckoo mimicry by evolving highly recognisable patterns on their own eggs, just like a bank might insert watermarks on its currency to deter counterfeiters," said Stoddard.

"The surprising discovery of this study is that hosts achieve this in different ways" said Kilner, from Cambridge's Department of Zoology.

Some host species have evolved egg patterns that are highly repeatable within a single clutch, while other species have evolved eggs with patterns that differ dramatically from female to female in a population. Still other host species produce egg patterns with high visual complexity. Each strategy is effective, increasing the likelihood that a given host will identify and reject a foreign egg. "Some species use two of these strategies, but none uses all three," continued Kilner. "A signature like this would be too complex to be easily recognised."

The patterns on bird eggs are just one type of visual signature. Identity signatures are common in the animal world, but how they are encoded and recognised is poorly understood. In the future, computational tools like NaturePatternMatch -- which account for important aspects of visual and cognitive processing -- will be crucial for understanding the evolution of visual signals in diverse biological populations.

The findings of this study are reported in the journal Nature Communications.


Story Source:

The above story is based on materials provided by University of Cambridge. The original story is licensed under a Creative Commons Licence. Note: Materials may be edited for content and length.


Journal Reference:

  1. Mary Caswell Stoddard, Rebecca M. Kilner, Christopher Town. Pattern recognition algorithm reveals how birds evolve individual egg pattern signatures. Nature Communications, 2014; 5 DOI: 10.1038/ncomms5117

Cite This Page:

University of Cambridge. "Birds evolve 'signature' patterns to distinguish cuckoo eggs from their own." ScienceDaily. ScienceDaily, 18 June 2014. <www.sciencedaily.com/releases/2014/06/140618071725.htm>.
University of Cambridge. (2014, June 18). Birds evolve 'signature' patterns to distinguish cuckoo eggs from their own. ScienceDaily. Retrieved July 31, 2014 from www.sciencedaily.com/releases/2014/06/140618071725.htm
University of Cambridge. "Birds evolve 'signature' patterns to distinguish cuckoo eggs from their own." ScienceDaily. www.sciencedaily.com/releases/2014/06/140618071725.htm (accessed July 31, 2014).

Share This




More Plants & Animals News

Thursday, July 31, 2014

Featured Research

from universities, journals, and other organizations


Featured Videos

from AP, Reuters, AFP, and other news services

Raw: Thousands Flocking to German Crop Circle

Raw: Thousands Flocking to German Crop Circle

AP (July 30, 2014) Thousands of people are trekking to a Bavarian farmer's field to check out a mysterious set of crop circles. (July 30) Video provided by AP
Powered by NewsLook.com
Concern Grows Over Worsening Ebola Crisis

Concern Grows Over Worsening Ebola Crisis

AFP (July 30, 2014) Pan-African airline ASKY has suspended all flights to and from the capitals of Liberia and Sierra Leone amid the worsening Ebola health crisis, which has so far caused 672 deaths in Guinea, Liberia and Sierra Leone. Duration: 00:43 Video provided by AFP
Powered by NewsLook.com
At Least 20 Chikungunya Cases in New Jersey

At Least 20 Chikungunya Cases in New Jersey

AP (July 30, 2014) At least 20 New Jersey residents have tested positive for chikungunya, a mosquito-borne virus that has spread through the Caribbean. (July 30) Video provided by AP
Powered by NewsLook.com
Xtreme Eating: Your Daily Caloric Intake All On One Plate

Xtreme Eating: Your Daily Caloric Intake All On One Plate

Newsy (July 30, 2014) The Center for Science in the Public Interest released its 2014 list of single meals with whopping calorie counts. Video provided by Newsy
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:
from the past week

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