Estuarine crocodiles (Crocodylus porosus) range from India to China to Australia — where the saltwater crocs are known as salties.
I like to think of them as sharks that will follow you onto the beach. While they predominantly live in rivers, mangrove swamps, and brackish estuaries, salties have also been found far off shore:
The researchers acoustically tagged 27 crocodiles from the Kennedy River in Australia. The team inserted small transmitters in the crocs and placed receptors along the river’s coastline.
Whenever a crocodile came within a quarter mile of the receptor, the movement was recorded. After a year of monitoring the reptiles along the river, the scientists discovered that they habitually travel from their home area to the river mouth, a distance upwards of 31 miles away.
Whenever the gigantic beasts traveled more than 6 miles a day, they surfed. The crocs always started their journey immediately after the tides turned, securing them a solid 6 to 8 hours of speedy travel.
Every time the tides changed to an unfavorable direction, the crocodiles took a rest stop. They retreated to the nearby shore for a period of hours to days.
As a short term solution to unfavorable tides, the animals would dive to the bottom of the river, where they can spend up to an hour lounging on the river floor, rather than moving back to land.
In a previous study, the researchers outfitted three crocodiles with satellite transmitters. This allowed the team to follow the “salties” — the Australian nickname for the predators — beyond the river mouth and into the ocean.
One of the crocodiles journeyed down the west Coast of Cape York Peninsula. The trip coincided with changes in seasonal currents. Over the course of 25 days, the salty moved a whooping 367 miles!
Similarly, two of its brethren also covered hundreds of miles in a few weeks.
Achieving these arduous journeys is made possible by the crocodiles’ acute sense of direction.
Estuarine crocodiles depend on an internal magnetic compass to reach their desired location, similar to birds and turtles.
Additionally, these reptiles can easily endure long trips and remain physically strong despite a lack of eating and drinking due to amazing internal engineering.
Saltwater crocodiles only drink fresh water and rely on ambushing prey, a strategy difficult to maintain during sustained ocean travel.
But the creatures developed the ability to maintain nutrients from ingested food long after feeding. As a result, they can last up to 4 months in the ocean without regular eating or drinking.