Featured Research

from universities, journals, and other organizations

From The Egg, Baby Crocodiles Call To Each Other And To Mom

Date:
June 25, 2008
Source:
Cell Press
Summary:
The pre-hatching calls of baby Nile crocodiles actually mean something to their siblings and to their mothers. The calls -- which are perfectly audible to humans and sound like "umph! umph! umph!" -- tell the others in the nest that it's time to hatch, according to research in Current Biology. Those cries also tell the mother crocodile to start digging up the nest.

For the first time, researchers have shown that the pre-hatching calls of baby Nile crocodiles actually mean something to their siblings and to their mothers. The calls--which are perfectly audible to humans and sound like "umph! umph! umph!"--tell the others in the nest that it's time to hatch, according to the report in the June 23rd issue of Current Biology. Those cries also tell the mother croc to start digging up the nest.

The new findings, made from a series of "playback" experiments, confirm what had only been suspected on the basis of prior anecdotal observation, according to the researchers Amélie Vergne and Nicolas Mathevon of Université Jean Monnet in France.

The researchers said that the calling behavior is probably critical to the early survival of the young crocodiles.

Although it has not yet been clearly shown, "We can well suppose that hatching synchrony can be of vital importance for crocodiles," Mathevon said. "Indeed, most mortality occurs early in life and hatching vocalizations might well attract predators. Therefore, adult presence at the nest and its response to juvenile vocalizations may offer protection against potential predators. In this sense, it is important for all embryos in the nest to be ready for hatching at the same time so that they all receive adult care and protection."

Crocodilians were known to make sounds within the egg shortly before hatching, the researchers said. To find out what those calls might mean in the new study, the researchers divided crocodile eggs that were due to hatch within 10 days into three groups. One of those groups was played recordings of pre-hatching calls, one was played recordings of noise, and the last was left in silence until they hatched.

The eggs played the pre-hatch sounds more often answered back, they report. Many of the eggs in that group also moved. Finally, all of the eggs in the pre-hatch group hatched during the playback or within 10 minutes of it. Only once did the eggs hearing noise hatch, and the rest hatched at least five hours after the last test.

The researchers then tested the mothers' responses to the calls. "In the zoo where we did the experiments, eggs are removed [from the nest] within a few days following the laying date," the researchers explained. "In spite of this, females continue to guard the nest."

At the end of the incubation period, the researchers hid a loudspeaker underground near the empty nest. They then played pre-hatching calls interspersed with noise to ten mothers. The adults more often turned their heads or moved after egg sounds than after noise, they showed, and eight of the mothers responded to the recorded calls by digging.

The behavior may have a long history, the researchers said.

"As birds also produce embryonic vocalizations that induce parental care, such acoustic communication at an early stage of development may be a shared behavioral feature of past and present Archosaurs," an ancient group of reptiles now represented by modern birds and crocodiles.

The researchers include Amélie L. Vergne, of Université Jean Monnet, Sensory Ecology and Neuro-Ethology Lab, Saint-Etienne, France, and Nicolas Mathevon, of Université Jean Monnet, Sensory Ecology and Neuro-Ethology Lab, Saint-Etienne, France, and Université Paris XI, NAMC CNRS UMR8620, Orsay, France.


Story Source:

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


Journal Reference:

  1. Amélie L. Vergne and Nicolas Mathevon. Crocodile egg sounds signal hatching time. Current Biology, 2008; 18 (12): R513 DOI: 10.1016/j.cub.2008.04.011

Cite This Page:

Cell Press. "From The Egg, Baby Crocodiles Call To Each Other And To Mom." ScienceDaily. ScienceDaily, 25 June 2008. <www.sciencedaily.com/releases/2008/06/080623125006.htm>.
Cell Press. (2008, June 25). From The Egg, Baby Crocodiles Call To Each Other And To Mom. ScienceDaily. Retrieved October 20, 2014 from www.sciencedaily.com/releases/2008/06/080623125006.htm
Cell Press. "From The Egg, Baby Crocodiles Call To Each Other And To Mom." ScienceDaily. www.sciencedaily.com/releases/2008/06/080623125006.htm (accessed October 20, 2014).

Share This



More Plants & Animals News

Monday, October 20, 2014

Featured Research

from universities, journals, and other organizations


Featured Videos

from AP, Reuters, AFP, and other news services

White Lion Cubs Born in Belgrade Zoo

White Lion Cubs Born in Belgrade Zoo

AFP (Oct. 20, 2014) — Two white lion cubs, an extremely rare subspecies of the African lion, were recently born at Belgrade Zoo. They are being bottle fed by zoo keepers after they were rejected by their mother after birth. Duration: 00:42 Video provided by AFP
Powered by NewsLook.com
Traditional Farming Methods Gaining Ground in Mali

Traditional Farming Methods Gaining Ground in Mali

AFP (Oct. 20, 2014) — He is leading a one man agricultural revolution in Mali - Oumar Diatabe uses traditional farming methods to get the most out of his land and is teaching others across the country how to do the same. Duration: 01:44 Video provided by AFP
Powered by NewsLook.com
Goliath Spider Will Give You Nightmares

Goliath Spider Will Give You Nightmares

Buzz60 (Oct. 20, 2014) — An entomologist stumbled upon a South American Goliath Birdeater. With a name like that, you know it's a terrifying creepy crawler. Sean Dowling (@SeanDowlingTV) has the details. Video provided by Buzz60
Powered by NewsLook.com
Hey, Doc! Sewage, Beer and Food Scraps Can Power Chevrolet’s Bi-Fuel Impala

Hey, Doc! Sewage, Beer and Food Scraps Can Power Chevrolet’s Bi-Fuel Impala

3BL Media (Oct. 20, 2014) — Hey, Doc! Sewage, Beer and Food Scraps Can Power Chevrolet’s Bi-fuel Impala Video provided by 3BL
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