British Wildlife of the Week
Culling animals is almost always controversial. In this day and age, killing wildlife – whatever your goal – can attract attention from people who fundamentally oppose such measures. In many cases, culling has questionable motives, other alternatives are available, and the evidence supposedly promoting such a move is scientifically unsound (here at The Nature Nook, we believe that badger culling in an attempt to eradicate bTB falls under this category). But, in other cases, when all other reasonable options have been exhausted, culling may be necessary – to protect, for example, a rare species from an introduced, alien predator. Several flightless birds in New Zealand have already been wiped out by the introduction of rats, cats, dogs and stoats to their natural environment, and many more still would almost certainly have become extinct had those alien species not been culled.
Today, we’ll be looking at an introduced species a little closer to home: the ruddy duck. It may look completely harmless, but it has nonetheless caused some serious ecological problems outside its natural range.
Like many other non-native animals here in the UK, such as the Canada goose and grey squirrel, the ruddy duck comes from North America. The drake is a russet-red colour, with white cheeks, a black cap, a stiff tail that is often held upright, and a blue, cartoon-like bill that looks almost glued-on. It’s a handsome duck and it certainly found its way into the heart (not to mention the collection) of the great conservationist and ornithologist Sir Peter Scott, who established the Wildfowl & Wetlands Trust in Slimbridge, Gloucestershire, in 1946. During the 1950s, however, a few ruddy ducks escaped, bred, and became naturalised. They gradually established themselves across the country and, by the year 2000, there were around 6,000 of these American ducks living wild in the UK.
But the ruddy ducks weren’t content with colonising just one country. Some of them expanded their range, dispersing south in search of a new home. Those that reached Spain encountered a similar and closely related cousin: the white-headed duck. Living on opposite sides of the Atlantic Ocean from one another, these two species had never met before. But now, ruddy duck and white-headed duck began to interbreed, producing fertile hybrids with intermediate characteristics.
The problem with this is that the white-headed duck is globally endangered. Interbreeding with the much commoner ruddy duck threatened the survival of the white-headed duck as a distinct species. Unless something was done, it was entirely possible that the Spanish white-headed duck population could effectively die out, undermining years of conservation work.
Since the UK was home to around 95% of the feral population of ruddy ducks in Europe at the time, the British government took the decision in 2005 to systematically eradicate the ruddy ducks that had colonised our country. Understandably, this caused passionate debate and controversy. The ruddy duck, though non-native, was a charismatic species that had won the affection of many British birders, and there were many who were vehemently opposed to the cull. Critics said that the cost would be better spent on habitat protection rather than maintaining the genetic purity of a single species, but most conservation organisations, including the RSPB, deemed it necessary in order to ensure the survival of the white-headed duck in Europe.
By 2010, around 90% of the British population of ruddy ducks had been exterminated. But sightings began to be suppressed in order to save the tiny population that remained from the marksmen. Fast-forward ten years and the ruddy duck is still here in the UK – just. The numbers are now tiny, probably barely into double figures. But these last few survivors have evaded detection and are still clinging on, holed up in remote ponds and wetlands, probably aided by local birders, who keep these final hideouts well-kept secrets.
This species has already demonstrated that it can form a self-sustaining population from a very small base, and perhaps, if left alone, that could happen again. But surely it’s only a matter of time before even these last vestiges of the ruddy duck population are gone too.
In the next British Wildlife of the Week, we’ll be looking at another animal whose very existence is being threatened by hybridisation – the Scottish wildcat.