Editing Crocodile (section)

===Social behaviour and vocalization===
[[File:Crocodiles resting together.jpeg|thumbnail|right|Captive crocodiles resting together with open jaws.]]
Crocodiles are the most social of reptiles. Even though they do not form social groups, many species congregate in certain sections of [[river]]s, tolerating each other at times of [[feeding]] and [[Body temperature|basking]]. Most species are not highly territorial, with the exception of the saltwater crocodile, which is a highly [[territory (animal)|territorial]] and aggressive species: a mature, male saltwater crocodile will not tolerate any other males at any time of the year, but most other species are more flexible. There is a certain form of [[hierarchy]] in crocodiles: the largest and heaviest males are at the top, having access to the best basking site, while females are priority during a group feeding of a big kill or carcass. A good example of the hierarchy in crocodiles would be the case of the [[Nile crocodile]]. This species clearly displays all of these behaviours. Studies in this area are not thorough, however, and many species are yet to be studied in greater detail.<ref>{{cite web |url=http://crocodilian.com/cnhc/csp_cnil.htm |title=Crocodilian Species List |publisher=Crocodilian.com |access-date=26 April 2013 |archive-date=25 October 2011 |archive-url=https://web.archive.org/web/20111025183255/http://crocodilian.com/cnhc/csp_cnil.htm |url-status=dead }}</ref> [[Mugger crocodile]]s are also known to show toleration in group feedings and tend to congregate in certain areas. However, males of all species are aggressive towards each other during mating season, to gain access to females.

Crocodiles are also the most vocal of all reptiles, producing a wide variety of sounds during various situations and conditions, depending on species, age, size and sex. Depending on the context, some species can communicate over 20 different messages through [[Animal communication|vocalizations]] alone.<ref>{{cite web|url=http://crocodilian.com/cnhc/croccomm.html |title=Crocodilian Communication |publisher=Crocodilian.com |access-date=29 April 2013}}</ref> Some of these vocalizations are made during social communication, especially during [[territory (animal)|territorial]] displays towards the same sex and [[courtship display|courtship]] with the opposite sex; the common concern being [[reproduction]]. Therefore most [[conspecific]] vocalization is made during the [[breeding season]], with the exception being year-round [[territorial behaviour]] in some species and quarrels during feeding. Crocodiles also produce different distress calls and in aggressive displays to their own kind and other animals; notably other predators during [[Interspecific competition|interspecific]] predatory confrontations over carcasses and terrestrial kills.

Specific vocalisations include&nbsp;—

* '''Chirp''': When about to hatch, the young make a "peeping" noise, which encourages the female to excavate the nest. The female then gathers the hatchlings in her mouth and transports them to the water, where they remain in a group for several months, protected by the female<ref>{{cite web|url=http://www.arkive.org/nile-crocodile/crocodylus-niloticus/|archive-url=https://web.archive.org/web/20090123041108/http://www.arkive.org/nile-crocodile/crocodylus-niloticus/|url-status=dead|archive-date=23 January 2009|author=Arkive|title=Nile crocodile (''Crocodylus niloticus'')|access-date=29 April 2013}}</ref>
* '''Distress call''': A high-pitched call used mostly by younger animals to alert other crocodiles to imminent danger or an animal being attacked.
* '''Threat call''': A hissing sound that has also been described as a coughing noise.
* '''Hatching call''': Emitted by a female when breeding to alert other crocodiles that she has laid eggs in her nest.
* '''Bellowing''': Male crocodiles are especially vociferous. Bellowing choruses occur most often in the spring when breeding groups congregate, but can occur at any time of year. To bellow, males noticeably inflate as they raise the tail and head out of water, slowly waving the tail back and forth. They then puff out the throat and with a closed mouth, begin to vibrate air. Just before bellowing, males project an [[infrasonic]] signal at about 10&nbsp;Hz through the water, which vibrates the ground and nearby objects. These low-frequency vibrations travel great distances through both air and water to advertise the male's presence and are so powerful they result in the water's appearing to "dance".<ref>{{cite web |url=http://factsanddetails.com/Asian.php?itemid=2435&subcatid=434 |archive-url=https://archive.today/20130629045148/http://factsanddetails.com/Asian.php?itemid=2435&subcatid=434 |url-status=dead |archive-date=29 June 2013 |author=Hays, J. |title=Crocodiles: Their history, characteristics and behavior |year=2008 |access-date=31 May 2013 }}</ref>