Using their large feet and fast stride, the Western and Clark’s grebes can run as far as 20 meters on water, making them the only bird and the heaviest animal on Earth capable of doing so.
If you exclude Jesus Christ, whose biblical feat of walking on water is literally considered a miracle of the New Testament, only a handful of creatures are known to be able to walk or run on water. Most of them are small insects, but there is also a small basilisk nicknamed the Jesus Christ lizard for very obvious reasons, but the largest of them all are two bird species – the Western and Clark’s grebes. They can run on water for up to 7 seconds and distances of about 20 minutes as part of an impressive mating ritual.
Photo: LHPT/Wikimedia Commons
Unlike the spiders and gnats that rely on their extremely lightweight frames to stick to the water’s surface, Western and Clark’s grebes rely on other unique advantages to run on water. These birds usually weigh between one and a half and four pounds, making them considerably heavier than other animals capable of walking on water. In fact, they are the heaviest animals capable of this remarkable feat.
For years, the ability of Western and Clark’s grebes to remain afloat for considerable distances as they ran on water eluded experts. Then, in 2015, a team of American scientists analyzed footage recorded using high-speed cameras to try and understand how the birds moved their feet. They found that the grebes relied on their big feet and extremely fast strides in order to perform their little miracle.
Specimens from these two species of birds use their broad, lobed feet to slap the water’s surface, which generates about half the force needed to counteract their weight. The way they lift their feet out of the water – to the side – also helps to reduce friction. But this alone isn’t enough. The grebes are also capable of moving their feet at a very high speed, taking up to 20 steps a second.
Interestingly, both Western and Clark’s grebes only perform their water run, also known as ‘rushing’, during their mating rituals, which means scientists can’t just take specimens into a laboratory and have them replicate the ritual. Because ruching has so far only been analyzed in the wild, using video footage, some mystery still remains around the way grebes use their feet underwater.
Although 7 seconds of running on water may not seem very long, it’s actually extremely impressive for such a large, heavy bird as the grebe, and some scientists refer to their ability as a sort of ‘magic’.
Once considered the same species, Western and Clark’s grebes are nearly identical and the unique characteristics each has are so subtle that only experienced birders can tell them apart.
