Have you ever walked the blanket bogs of Dartmoor? They can seem like an empty, open, drear place with little wildlife and an apparently limitless expanse of Molinia – a Chameleon-like grass which changes in character from purple-tinted green in summer to winter white. You may have heard the bubbling trill of Skylarks, the 'sweet-sweet-sweet' calls and songs of Meadow Pipits and perhaps, in the loneliest and most remote areas, the dry trilling calls of Dunlin. Other than these hardy birds and a specialist invertebrate fauna, you could be forgiven for thinking the place was pretty empty. Not so: take time, walk quietly and spend some time looking carefully at those bog pools – some are the home of a very special mammal: the Dartmoor Pygmy Sperm Whale. Known scientifically as Microkogia devoniensis, this is not only the sole freshwater European cetacean, but is also the world’s smallest whale; and it is a shy endemic resident of open bog pools on the blanket mires of Dartmoor.
The Dartmoor Pygmy Sperm Whale is a fraction of the size of its better-known relatives - which include the world’s largest animal (the Blue Whale, Balaenoptera musculus). Measuring a maximum of 16cm from nose to tail, this is a unique creature in many different ways.
Much remains to be discovered about the biology and ecology of these diminutive specialities of the Dartmoor uplands. They appear to spend much of their time feeding in amongst the fringes of the Sphagnum moss which grows into the pools, perhaps hunting small invertebrates or even freshly-hatched tadpoles. There has been speculation that they even burrow their way into the mats of Sphagnum, though there is as yet no evidence of such behaviour. Their whereabouts in winter are also a mystery, although there have been reports of sightings at the ice fringe in the hardest weather, suggesting they probably remain faithful to their summer haunts throughout the year. It seems likely that they are able to live off their fat reserves through the tough winter conditions.
Your best chance of seeing one of these remarkable beasts is to find a bog pool, sit quietly and scan the water’s surface for the telltale ‘blow’ the animals make when they come to the surface. Their diminutive size means they surface rapidly, and even in a light wind, the ripples on the water’s surface can be sufficient to hide them. They rarely lift any part of their body far clear of the water, although tail-slapping and fin-beating are not unknown during their spring courtship period. However, other typical cetacean behaviour such as breaching is as yet unknown in the species.
Keep a close eye on the water when you're out there...