Could hybrid Wildcats be the key to saving the Scottish Wildcat?

The Scottish Wildcat is rare. It may potentially be one of the rarest (if not the rarest) mammal still existing in the wild. Some estimations predict as few as 35 wildcats in the wild, others as many as 400. Both of these estimations are low enough that the wildcat will not be able to recover naturally, in the wild.

I’m sure that most people are aware of the major reasons for the low population. Habitat fragmentation has a major impact; as existing populations are unable to reach potential mates. The wildcat is clearly not bothered what they reproduce with, as long as they make kittens. Breeding behaviours can be complex, and wildcats can be extremely aggressive. A tame domestic cat may be preferable, why risk losing an eye when you don’t need to. All of these factors have led to the wildcat genepool becoming smaller, polluted and diluted. Hybridised wildcats are therefore much more common than the “pure blooded” individuals.

A true wildcat can be extremely difficult to identify, different individual display different levels of visible hybridisation. The only way to be truly certain is through DNA testing. Identifying a wildcat in the wild is even more difficult. My twin brother, who is also an ecologist, tells me that every wildcat report he has is always a pain. He knows the chances of their being a true wildcat, though each report needs to be investigated. He also tells me that pretty much every wildcat report he receives is from an ornithologist, read into that what you will. Only an experienced expert can identify a wildcat visually, even then they can never be certain. This was exemplified, when it was discovered that both wildcats at The Highland Wildlife Park, are actually hybrid cats.

Steve Piper, is a wildcat expert and a founder and former chairman of the Scottish Wildcat Association. Piper claims that leaked information from the society suggested hybrid animals were being bred.

He quotes Douglas Richardson, the organisation’s head of living collections at The Highland Wildlife Park, as saying: “We have also applied this three-way test to our resident cats at the Highland Wildlife Park, and it came as no surprise that the majority of our ‘wildcats’ proved to be of hybrid origin to one degree or another; the same is very likely true for the majority of the captive population within the UK.”

Identifying a Wildcat

The website of  wildcat conservation group “Wildcat Haven” suggests that the main and most obvious identifier is the tail. The wildcat’s tail is very thick, almost club-like, with bold distinct rings around it. In a hybrid the rings around tail are likely to be thinner and less distinct. Other characteristics of  wildcats include the dorsal stripe, which  is also more clear and always stops at the base of the spine, leaving a plain area around the rump. In a hybrid the dorsal stripe continues down the tail and causes the stripes to become misshapen.

Second are the body markings. A domestic tabby has patches of pure white, spots or broken up and messy stripes. Wildcats have brown fur around the mouth, no white flash on their chest, and tiger-eques stripes. A hybrid is usually a mix of the two. The stripes can be very distinct, just as thick or even thicker than a pure wildcat, but it will have spots too. Rings around the legs are fewer and thicker than a pure wildcat, and the stripes on the head are thicker and slightly differently positioned.

These features are not mutually inclusive however, and hybrids can on occasion have some perfect wildcat features. For example, a domestic cat’s can have a banded tail, but it won’t be club-like, or a hybrid will have a club-like tail, but the bands will be oddly shaped or partly connected by a dorsal stripe. A cat must have ALL perfect features to be a pure Scottish wildcat.

So should we be worried?

I realise this is potential an extremely controversial statement but, would be as great a tragedy if the genetically pure Scottish wildcat becoming extinct, as it is being made out to be? In fact, could the domestic cat be the only chance the wildcat has for survival?

Ok, hear me out before you get angry.

One of the keys to a successful population of any animal species is genetic diversity. Genetic diversity produces more intense levels of natural selection, resulting in healthier population with an increased ability to adapt to change. This creates much more stable populations. On the other hand, things such as population bottlenecks and inbreeding reduce the stability of a population, and reduce the ability to adapt to small changes. Simply put, a population with genetic diversity below a certain limit is doomed to extinction.

The genetic diversity of the Scottish wildcat is extremely low. Population fragmentation means that the gene pool is weak. Individuals within a breeding population are likely to be, at least in some level, related to each other. The size of the gene pool means that we many only really reducing the inevitable. Even with reintroduction programmes the population diversity is likely to be low, even if individuals are taken from countries with higher genetic diversity.

Unlike the wildcat, domestic cats have extremely high genetic diversity. The vast majority of pet cats are not pedigree cats (were genetic diversity is low) and it is even greater in feral cats, as they can reproduce freely. Could it be that the best chance the wildcat has to survive, is by reproduction with domestic cats?

The European Wildcat Felis silvestris silvestris and the Domestic Cat Felis catus or Felis silvestris catus are extremely closely related. We know this, if they weren’t so closely related they wouldn’t be capable to reproduce viable offspring.

So is it really make much of a difference if the majority of wildcats are not completely pure? As mentioned earlier, there is almost no physical difference. They are capable of reproducing and maintaining a stable wild population. Hybrid wildcats take up the same ecological niche as the pure wildcat, and a hybrid cat could easily live within any population of pure wildcat undetected. The hybrids are out there, in the wild, being wildcats.

Hybrid wildcats might be the key in helping to increase the genetic diversity of all the wildcats by introducing the genes of domestic cats. By allowing the population of hybrid wildcat to reproduce, it may help reduce the levels of habitat fragmentation and inbreeding, reducing levels of genetic drift and ultimately save them from extinction. By increasing gene flow, the genetic diversity between the two closely related population is increased, ultimately reducing the genetic difference between the groups as they breed in larger populations. Although the end result would not be a 100% pure wildcat, as defined by us, it may ultimately help increase the population of a Scottish wildcat with genetic diversity increasing, and genetic difference decreasing over time.

What I am trying to say, is that the proposed culling and neutering of hybrid wildcats could be cause more harm than good. The hybridisation of the wildcat, although caused by humans, is essentially a natural process. Many may see hybridisation as a form of genetic pollution, it may however be the only chance any Scottish Wildcat has. Hybridisation is part of evolution. The view of a tree of species, is not an accurate one and in many ways the idea of individual species is la human invention.

Do we perhaps need to re-access what we are doing? Ironically, we are actually deliberately producing hybrid cats, by inter breeding both hybrids and cats taken from other countries. Which are pure, are any pure, does it matter? It is a complex argument, and I am not certain it is one that is going be resolved.

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Ben Wright

Ben Wright

I am a consultant ecologist with a special interest in protected species and birds. I have some past experience in science writing. I formally wrote a science column for a local paper, and composed a book based on the column (Science Matters) which has just been published.

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