Study: baby crocs inside eggs cry for mother

BEIJING, June 24 (Xinhuanet) -- The noises baby crocodiles make inside their eggs before hatching are cries to their mother for help, according to a new study.

The new study, which involved playbacks of the pre-hatching calls, reveals these calls from the within egg tell siblings it's time to hatch and tell moms it's time to uncover the nest.

Researchers Amｅlie Vergne and Nicolas Mathevon of the Jean Monnet University in France monitored Nile crocodile (Crocodylus niloticus) eggs that were due to hatch within 10 days. The eggs were placed into one of three groups, for which the researchers either played recordings of pre-hatching calls, recordings of noise (other than the calls), or no sound.

The group of eggs that got a dose of real croc calls responded and moved, as the about finger-sized babies jostled about, more often than the "noise" eggs. The eggs incubated in silence showed no movement.

All four of the individuals that successfully hatched in the croc-call group did so during or within 10 minutes of the playbacks. The pre-hatchlings in the noise group broke through their shells no less than five hours after the last playback.

After the eggs hatched, the moms-to-be stuck around to continue their nest guarding. The researchers found the female crocodiles responded to pre-hatching playbacks coming from loudspeakers hidden underground near the now-empty nests.

The female adults more often turned their heads or moved after egg sounds than after noise, and eight of the 10 mothers began digging in response to pre-hatching calls. The nests are covered with soil during the months-long incubation.

(Agencies)