Crocodiles are master predators in the water and on land, but new footage from the BBC shows that the air is not safe from their jaws either.
For tropical animals the dry season poses a problem. Sources of fresh water become limited or dangerous. The little red flying foxes (Pteropus scapulatus) of northern Australia need plenty of water to sustain their high-energy lifestyle, but to get it they have to contend with Crocodulus johnstoni, the Australian freshwater crocodile.
C. johnstoni seldom grow much past two meters in length or attack humans, unlike their terrifying saltwater cousins, but they are more than a match for a bat. For the Wonders of the Monsoon documentary, director Nick Lyon and camerman Warwick Sloss filmed the encounters with night vision and super fast lenses for the first time.
“The only way to film this was from a small boat,” Lyon says. “This meant navigating up the river in daylight, but more scarily the behaviour happened at dusk, so by the time we'd finished filming I had to remember the route back in pitch black through lots of hazards like sunken logs. It was only when the torches were turned on you could see how many crocs were in the river, and all eyes were trained on us.”
Only on the last scheduled day did the team get the footage they wanted.
The crocodile metabolism lacks stamina, but offers explosive bursts of energy, and Britton says, “I've seen crocs get 2-2.5m out of the water to get birds. Saltwater crocs in particular will sit under roosting fruit bat colonies. The bats are squabbling all the time, trying to get closer to the water to escape the sun. The crocodile will wait for a bat to roost within range.”
Britton adds that it takes little energy for the crocodile to leap in this way, so they “can afford to miss a few times” for each bat they catch.
It is not known how much of the crocodile's diet the bats represent. Britton says crocodiles will travel several hundred kilometers to a place where a particular food is plentiful for a season before moving off elsewhere.
Britton, who did his Ph.D. on bats before moving onto reptiles, says he remains puzzled by the bats' drinking strategy. “Microbats fly down to the water, then hold their wings above their body and glide, dipping their heads down to run their tongue through the water.” Britton thinks the flying foxes however are wetting their fur so they can lick the water later.
The film may help explain the reasons for the preferred strategy. Britton says, “A lot of discoveries about animal behavior get made these days through high-speed footage. This behavior has been filmed before, but never in high speed so it was impossible to see what was going on.”