It's a move called "pronking", and it's guaranteed to make you smile. What a day. What a lovely day! 

Dave Mott has been walking his dog along the shores of Poole Harbour in Dorset, England for 16 years, but until this week, he'd never seen a sika deer. It's thought this particular bounding animal made its way over from nearby Brownsea Island, which houses a nature reserve managed by the Dorset Wildlife Trust.

Sika deer (Cervus nippon) are native to Japan, and were introduced to Brownsea after being brought over for a show in the late 19th century. The move seemed harmless enough, but in an unexpected twist, the deer turned out to be competent swimmers, and with the ebb and flow of the easy summer tides, they waded from island to island. As you can see here, watching deer emerge from the sea is a sight still enjoyed by the occasional beachgoer. 


 

While the deer looks cheery as all get-out, pronking (also known as "stotting") is often viewed as a threat display – a way to say, "I'm fit, don't even try it." In fact, the behaviour is seen in other animals too. African antelopes also do it – just look at this aptly named springbok:

There are other theories out there to explain why four-legged creatures take to pronking. It's is an inefficient way to escape, so some speculate the high jumps act as a warning to other herd members instead. (If you're toast, you might as well sound the alarm with a bit of flair.) Others suggest the behaviour confuses would-be predators.

But none of these explanations really fit the Poole Harbour scenario. The sika's antics, the Dorset Wildlife Trust explains, probably come down to sex. "We're heading into rutting season," they said, noting that while sika are an impressive sight, it's best to give them a wide berth during the rut. A display of high bounding might detract predators, but it likely does the opposite for a potential mate. If you can bounce really high, chances are you've got stamina. 

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Top header image: cactusbeetroot/Flickr