Parent- offspring communication is a common topic of study for signal observation in many animals. Although it is not so common in reptiles, these types of behaviors are displayed readily in birds and mammals. All crocodilians make a “hatchling call” both when inside the amniote egg and as a juvenile.
Much like the group project we recently completed, the authors of this study were interested to determine whether there were physical characteristics of the individual’s calls that mother crocodiles could use to distinguish their young. The authors found that although individual recognition is not clearly observed in Crocodylus niloticus, the acoustic signals may serve as an indicator of mood and level of development. These signals can aide in the mother’s ability to protect the young in the best way possible for the context it is provided.
This study does show that although individual vocal recognition may be unlikely, the calls that individuals may produce will change with maturation in the juvenile stages. With the “still in egg” call that consists of a swift up-sweap, and the after hatched “distress call” involving both the up-sweap and a down-sweap in pitch. This method also shows that fundamental frequencies of these calls decreases with a juvenile crocodiles age. Instead of using Raven to do the acoustic analysis, this study utilized two software programs, Syntana and PRAAT.
posted by: Jeremy Ross
That's an interesting study. Did the authors go into how they came to the conclusion that there was no individual recognition? It would be interesting to know what type of experimental design was used. Awesome blog!
ReplyDeleteposted by: Jess Bouchard
Interesting post. I thought it was interesting that they did not find any evidence that their are characteristics of individual calls that allow mother crocodiles to distinguish their young. How responsive are the mothers to the juveniles' calls? If individual recognition was not observed, how do the mothers know that the juveniles making the calls are their own offspring?
ReplyDeletePosted by Sarah Benjamin
It's interesting that communication is seen even before hatching. Do the parents make noises back or are all the vocals made by just the hatchlings?
ReplyDeleteBecause parents can not recognize individuals by their vocal signals, do any adult crocodiles answer a call made by the hatchling?
-Tricia Carlson
Did the article mention what the "in egg" vocalization may mean? I think it is extremely interesting that the fetus can vocalize while still in the egg! Do you think by vocalizing while in the egg and after being hatched would attract attention by predators? I would think that predators walking by would take advantage of the eggs if the mother was away from the nest. Extremely interesting blog!
ReplyDelete-Sara Ku