No GPS Necessary for Cane Toads

By: Owen Lang

Have you ever gotten lost and wished that you had a built-in GPS to help you get back home? A built-in navigation system is one way that other animals have humans beat. Many animals have a built-in navigation system, such as migratory animals that need to be able to navigate to arrive at their destination and find their way back home after their trip. Territorial animals also need to be able to navigate, which lets them leave their territory when needed but also return to defend it when necessary. Many species of amphibians, the group of animals including frogs, toads, and salamanders, can navigate but the species we have found so far that do so either migrate or are territorial. Whether non-migratory and non-territorial species can navigate too is unknown to us. Daniel Shaykevich from Stanford University and his team of researchers wanted to figure out if cane toads can find their way back home when relocated, despite them not migrating or being territorial.

To investigate this question, the team attached radio trackers to cane toads in the rainforests of French Guiana and tracked their position for at least a week to figure out each toad’s home range (the area in which an animal spends its time in). After confirming that the toads studied showed site fidelity, meaning they returned to an area they had previously been in within their home range, the researchers relocated the toads both 500 m and 1000 m away from their home sites. They tracked the toads for ten days after relocation to see if the toads returned home by themselves. The pathways the toads travelled after being relocated and the time it took to travel from the relocation site back to their home ranges were recorded to understand how efficient their travel was.

They found that five out of the six toads that were relocated 500 m away returned to their home ranges in a straight path within three days. The ability to return home shows that cane toads are able to navigate and can do so efficiently, by taking the shortest path, over short distances. When relocated farther away (1000 m), two of the five toads returned home in a straight path within five days, while two more headed in the correct direction towards home but stopped short. Despite not all the toads making it all the way back home, the cane toads demonstrated the ability to orient themselves and navigate towards a destination over longer distances too.

Shaykevich and his team found that cane toads can navigate effectively back to their home range when relocated. Cane toads’ ability to navigate means that navigation is present in non-migratory and non-territorial animals too, which is an important finding since it could mean that navigation is more widespread in amphibians than we previously thought. If the ability to navigate back home is widespread, it could mean that relocated animals from peoples’ properties may be able to return. Cane toads are also invasive in numerous areas around the world, like Australia, so their ability to navigate could enhance their ability to spread in these regions. With these insights into cane toads’ ability to navigate and return home, it looks like the Terminator isn’t the only one who will be saying “I’ll be back.”

Shaykevich, D. A., Pašukonis, A., O’Connell, L. A. (2022) Long distance homing in the cane toad (Rhinella marina) in its native range. Journal of Experimental Biology. 225, jeb243048.