There were ‘water rats’ in Limerick when I was a boy. We stalked them in Westfields Marsh, to see their webbed feet. It was a futile quest; neither water rats, nor their supposed webbed feet, exist. The creatures we encountered were ordinary brown rats. A schoolbook was partly to blame for the confusion. Kenneth Grahame’s animal fable, The Wind in the Willows, might be one of the most evocative titles in literature, but it has misled countless young readers. Its water rat character, ‘Ratty’, was a vole. Rats and voles belong to different families.
Cuddly little water voles have brown fur, rounded noses, and blunt muzzles. Active mainly by day, they don’t need large eyes. The ears are rounded, not pointed and sticking out, like rat ones. The tail is shorter, and partly furred, as are the feet, which are not webbed.
Whereas rats eat everything and anything, voles are mainly vegetarian; you never find them rummaging in cesspools and filth. Individuals may consume up to 80% of their body weight in a day. Voles have even been accused of causing ‘feeding plagues’ in Europe; during sudden population surges, crops can be damaged.
We had no voles in Ireland prior to the 20th century. Then, in 1964, a bank vole was found near Listowel. The species has now colonised about a third of the country. There are various theories as to how voles got here. The least implausible one is that they stowed away in a shipment of machinery from Germany. Although it’s an ‘alien’, the bank vole hasn’t impacted adversely on the environment and so it shouldn’t be described as ‘invasive’.
Elsewhere in Europe, barn owls come out in daylight to hunt voles. Irish owls don’t emerge until darkness descends, when mice and rats become available. It’s not surprising, therefore, that barn owls are so difficult to see here. Irish kestrels, on the other hand, are more active during the fading evening light than ones elsewhere. Having no voles to catch, they targeted nocturnal rodents. If bank voles become more widely available, perhaps the behaviour of our owls and kestrels will change.
When Grahame’s novel appeared, in 1908, water voles were a familiar sight along the Thames, in Berkshire, where he lived. Indeed, there was hardly a pond or river in Britain that didn’t have them. Not any more; Ratty’s descendents have fallen on lean times. The pristine habitats that water voles need have been destroyed or polluted. Foxes, stoats, weasels, cats, and birds of prey traditionally hunt voles, but the little creature managed to hold its own, despite the fearful odds, until that voracious predator, the mink, arrived from America.
Facing so many enemies, it’s not surprising that voles are short-lived. Their life expectancy, on average, is just five months, so a high reproductive rate is required. A female may produce up to four litters a year, each containing four to six young. Nonetheless, water-vole numbers have declined by 90% in Britain since the mink’s arrival. All is not lost, however; reintroduction projects are being implemented. A major one has just got underway in Northumberland.
Kielder Water, a huge reservoir, adjoins the largest stand of man-made woodland in England. The area had a healthy population of water voles in the past, but none has been seen there in twenty years. With careful nurturing, the otter population has increased, displacing mink from the area, a prerequisite for successful vole rehabilitation. In the initial phase of the reintroduction, 300 voles have been released at eight locations there.
The introduced animals were bred from wild ones captured in Scotland. A further 350 voles will be released later this year. To enhance genetic diversity, they will come from a different source population.