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How do crocodiles communicate with vocalizations?

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Illustration of an estuarine or saltwater crocodile (Crocodylus porosus) with its mouth open, showing scaly skin and powerful limbs, alongside a scale bar for size reference. — crocodile Estuarine, or saltwater, crocodile (*Crocodylus porosus*), found in brackish waters from Sri Lanka, India, Bangladesh, and Myanmar east to the Solomon Islands and Vanuatu and south to Australia.

Crocodiles and other members of the order Crocodylia utilize a variety of vocalizations to communicate for purposes such as defense, social interaction, and reproduction.1

Young: Hatchlings and young crocodiles produce squeaking, grunting, or quacking sounds.1
Adults: Mature crocodiles communicate using grunts, growls, and hisses. For instance, Siamese crocodiles and caimans emit loud hisses when they feel threatened.1
Breeding: During the breeding season, both sexes may produce a loud roar. To achieve this, a crocodile tenses its body muscles, causing its head and tail to rise out of the water, while its flanks vibrate so intensely that water is sprayed into the air. Similarly, male alligators use bellowing roars to establish breeding territories and attract females.12

These vocalizations can be triggered by various external stimuli, including loud noises like gunshots, motors, or even people mimicking crocodile sounds. In addition to these auditory signals, crocodiles also appear to communicate using chemical signals excreted from glands in the mandible and cloaca.13