The trouble with mongrels

I wanted to try writing more meaty topics, so this is a bit longer and more serious than my other posts…

As a species we have had a pretty big impact on our planet and all who live here with us. Our influence extends to the deepest oceans and the highest mountains. We have even changed our atmosphere. While we label many species, habitats and places as ‘wild’, ‘natural’, ‘native’, or even ‘untouched’, these labels really start to lose their meaning when you consider just how much of our planet has been touched by us.

Yet often we act as if these labels still have genuine meaning. We try to ‘protect nature’ in small packets of land, and then monitor and maintain these islands to ‘keep them natural’. Genetic purity of rare or endangered species is jealously guarded and protected. We get agitated when one species that has benefitted from humans eats, kicks out or breeds with another species that has suffered at our hands.

But wait: why this divide between human and natural anyway? We evolved out of the primeval swamp just like every other bug, plant and animal. While we have found ways to manipulate, control and change our surroundings and fellow earthlings, we are just as much a product of Mother Nature as Bambi and Thumper, surely? We’ve certainly made a mess of the place, but we’re not exactly in a position to put everything back how we found it.

While a part of me would love to see the planet restored to pre-human, or at least pre-industrial condition, this isn’t going to happen. So how far should we go to protect and preserve species and habitats, and is it time for a more pragmatic, realistic form of nature conservation? Species hybridisation is a good place to start in examining the issues: just what is the trouble with mongrels?

Randy ruddys

The ruddy duck is native to the US but enough captive animals escaped in the UK to form a viable breeding population. So far no problem: we have nothing like the ruddy duck here, the birds posed no threat to UK natives and were generally seen as a welcome addition to the British wildlife scene. But after a while our ruddys started migrating to mainland Europe, where Spain is host to a cousin of the ruddy, the white-headed duck. A duck with problems if ever there was one, the white-headed came close to extinction in the 1970s and is still struggling today. And outrageously, the female white-headeds fell head-over-heels for the male ruddys and produced fertile crossbreed offspring. The Spanish were not amused, and to cut a long story short nearly all the 4000-6000 strong UK ruddy duck population has now been culled.

In the eyes of those who called for the cull, the ruddy duck had committed two crimes: it had arrived in the UK through human – not natural – means, and it had interbred with a duck that we humans consider to be a separate species. While unfortunate for the ruddy, this example throws an interesting light on our relationship with our wild neighbours.

What’s the problem with immigration?

Movement of populations from one place to another is not exactly new. All species – including humans – evolve someplace and then spread out to colonise new places. This colonisation process may or may not be detrimental to the original inhabitants.

In Britain the ice age created a blank sheet from which all our ‘indigenous’ inhabitants started from, trekking or flying across the land bridge between Britain and Europe. The first intake of humans was aggressively added to by Romans, Anglo Saxons, Vikings and Normans. These invaders brought with them animals, plants and birds that had failed to cross the land bridge. Rabbits, fallow deer, edible dormice, rosemary, thyme, walnut and sweet chestnut were all brought to Britain by these invaders.

If we are responsible for moving species from one place to another, does this mean we should feel obliged to ‘put them back’? I think the answer to this should always depend on the situation: have we really screwed up this time (think cane toad and Japanese knotweed), and is it worth the effort anyway (think grey squirrel and sycamore)? But really, I’d like to see conservationists get a little less hung up about how this species got to that place. If it’s not being too much of a nuisance let it be.

With hybrids, where the parents can breed naturally but are only doing so because we introduced them, we get upset because some animals or plants have mixed up their genes with our help. But why should this be a problem? After all, no one gets harmed as a result of the liaison.

Species purity: what’s the fuss all about?

What is a species anyway? In lay terms, if they can produce viable offspring and choose to do so, they’re the same species or sub-species. If the ruddys were allowed to mate with the white-headed ducks, the gene pool would expand, but would the white-headed duck become extinct? And would this be bad for the Spanish population of stiff-tailed ducks?

I think our problem with hybrids stems from our obsession with pedigrees. We love creating and refining breeds. Plant breeders are a lot less fussy about pedigree – they care about their cultivars having the desired characteristics, but this is often achieved through cross-breeding. But in animals it’s a different story. A pedigree dog can be worth so many thousands of pounds. But if the parents don’t have the right paperwork, in the breeding and showing world it is worth nothing.

Yet actually genetic diversity is a good thing. Pedigree animals and rare breeds can have huge problems – deformities, physical weaknesses, behavioural problems, and even killer genes. Yet some of us value these animals more than we do the cross-breeds and mongrels. In the natural world, those animals most vulnerable to extinction tend to have the least genetic diversity. They no longer have the flexibility to adapt to changing environmental conditions, or they cannot breed out harmful genes.

Going back to the white-headed ducks, it turns out that they are suffering from a genetic bottleneck and have been unable to respond to pressures such as hunting and habitat change. By accepting their ruddy suitors the female white-headeds may actually help protect the species by introducing much-needed new blood. But no, the hybrids are not white-headed ducks and must be eliminated. Well done Spain.

Domestic animals and plants cause all sorts of upset too. Now where the difference between wild and domestic really lies deserves a blog of its own, but in most cases domestic species are still closely enough related to their wild ancestors that they can still reproduce with each other. Enter the domestic cat!

Naughty moggies

Not content with killing our native birds and mammals (the task they were originally brought here for), the domestic cat, felis catus,  has had the gall to interbreed with the UK’s only wild cat, felis silvestris silvestris. The Scottish wildcat is a remnant population of the European wildcat, which is itself considered to be a sub species of the wildcat felis silvestris which ranges across Europe and Africa and from which all domestic cats are descended. While our Scottish population is under great threat, the species as a whole is not in danger.

The Scottish wildcat has suffered greatly from hunting and habitat loss, and more recently from interbreeding with domestic cats. As with the ruddy duck, this raises some interesting questions. If the cats are related to each other, and choose to breed together, what’s the problem? Also, we think that cats initially domesticated themselves, so should we get worried that domestic cats eat (or at least kill) our wildlife, and should we worry at all that the Scottish wildcats have taken a fancy to their domestic cousins?

I think that if the cats don’t have a problem mixing, and the hybrids do all the things the ‘pedigree’ wildcats do, we should just leave them to get on with it. It may even be good for our wildcats to get a bit of a genetic refresh. If we take the view that cats domesticated themselves anyway, we can feel even less guilty about all the naughty things our moggies get up to. It’s true that most domestic cats are well fed and kill things seemingly for the fun of it, but certainly our feral cats do no more or less than the wildcat would if we hadn’t persecuted it and driven it to the wildlands of Scotland.

So I say let’s all be a bit more sensible about our relationship with our fellow earthlings. Live and let live. If we have taken advantage of other species (or they have taken advantage of us) let’s not worry so much if cousins take a shine to each other, as the ruddy duck and wildcat examples highlight. We are not the genetic police. Nature usually knows best, and I reckon both the white-headed ducks and Scottish wildcats will actually benefit from their breeding choices, even if their offspring no longer carry the right paperwork.

Useful Links

Ruddy duck v white headed duck


Animal Aid:

Defra ruddy duck project:


Scottish wildcat v domestic cat

Scottish Natural Heritage:


More wikipedia links



Genetic pollution:


About Yasmine

After working with horses for many years I came to my senses and got a 'proper job'. I now live in Weardale with My Taller Half, a mad border collie and 5 chickens. Still wishing I could spend all my time in the great outdoors
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8 Responses to The trouble with mongrels

  1. Couldn’t agree more. Nature sorted itself out for millions of years and did just fine! Its only since we came along with our biblical “dominion over all living things” that there’s been a problem! I had a golden retriever and a mongrel dog and the mongrel is far healthier than the retriever, who died earlier last year – the mongrel is still going strong with no health problems at 13. We are so ego centric as a race.
    I think the many problems that face the human race have been caused by the removal of ourselves from nature. We are biological/natural beings and the last few hundred years have “progressed” too quickly for our bodies to keep pace. Hence the many mental health problems that face us. I always feel so much better when I get out and about amongst the trees, rivers and countryside.
    You may be interested to have a look at my blog – theres a bit on there about saving (or not?) the panda.
    I have subscribed to your blog, reckon we think along same lines?
    Happy times in the great outdoors!

  2. Yasmine says:

    Thanks for your comments Helen. I was looking at your blog the other day. I can’t quite remember how I found it but I will definitely have a proper explore later.

  3. Very well said Yasmine. I too carry incorrect paperwork so I fully endorse your blog! Happy New Year.

    • Yasmine says:

      Thanks Keith. I think there’s a lot of us about – me included.
      The arguments used to support culls to stop interbreeding wouldn’t be tolerated if applied to humans (apart from BNP supporters of course). It all gets me quite hot under the collar!

  4. Val says:

    If we humans would only stop considering ourselves the ‘dominant species’ this crap wouldn’t be happening. I appreciate your points in this post as it’s the sort of thing I’ve often wanted to write, myself.

  5. nebbie916 says:

    I couldn’t agree more about what you said about species and subspecies hybrids. Supporters of species/subspecies genetic purity in Scottish wildcats and the culling (by neutering) of free roaming domestic cats to stop the interbreeding between the two wildcat subspecies would not be tolerated if they applied the genetic purity thing to humans. If promoting genetic purity is rightly considered reprehensible when applied to humans, why is it considered to be such a different thing when other animals and organisms are concerned. Why the double standard?

    Here is another biology related subject that is not mentioned much, taxonomic subjectivity.

    There is some taxonomic subjectivity among the different wildcat (Felis silvestris) subspecies. The five main subspecies are the European wildcat (Felis silvestris silvestris), the Near Eastern wildcat (Felis silvestris lybica), the Southern African wildcat (Felis silvestris cafra), the Central Asian wildcat (Felis silvestris ornata), and the Chinese Mountain cat (Felis silvestris bieti).

    The most notable example of taxonomic subjectivity is between domestic cats and Near Eastern wildcats. The domestic cat descended from the Near Eastern wildcat through self-domestication and both are in the Lybica clade of wildcats. However, the domestic cat is labeled as either a separate subspecies (Felis silvestris catus) of wildcat or a separate species (Felis catus) of cat despite being nearly genetically identical to wild Near Eastern wildcat. Because the domestic cat hasn’t diverged much from its ancestor, I think that that the domestic cat should be left as part of the lybica subspecies.

    There are a few other examples of taxonomic subjectivity in wildcats.

    1) Until as recently as the year 2007, the Southern African wildcat and the Near Eastern wildcat were considered one subspecies, labeled under the scientific name, Felis silvestris lybica.
    2) Until recently, the Chinese Mountain cat was considered a separate species, labeled under the scientific name, Felis bieti.
    3) The Scottish wildcat, which is part of the silvestris subspecies, is often labeled the scientific name, Felis silvestris grampia. Two other subpopulations of the European wildcat that have their own subspecies name are the Spanish wildcat (Felis silvestris tartessia) and the Caucasian wildcat (Felis silvestris caucasica).
    4) The Arabian of Gordon’s wildcat, which is part of the lybica subspecies, is often labeled as Felis silvestris gordoni
    5) The Kalahari wildcat, which is part of the cafra subspecies, is sometimes labeled as Felis silvestris griselda.

    • Yasmine says:

      Thanks nebbie916 for your comments and the information on subspecies. Scottish wildcats are featuring heavily on BBC Winterwatch this week. Needless to say, I have been shouting at the telly a lot!

  6. nebbie916 says:

    I don’t see or hear that much information about the wildcat species, whether the species in general or its subspecies in particular. The only exception is the European wildcat and its critically endangered subpopulation in Scotland that used to live all over Britain. I understand perfectly that you want to protect and conserve endangered and critically endangered species and subspecies. You don’t want species and subspecies to go extinct. The only other exception to there being little info on the different wildcat subspecies is the Near Eastern wildcat, and that is only in relation to them being forbears to the self domesticated domestic cat.

    Whenever you find a website with info about the African wildcat, whether the cafra Southern African one or the lybica Near Eastern one, even on websites more recent than 2007, the two subspecies are mentioned as though they were just the one subspecies they were called before. I bet that a majority of those sites that have info on the African wildcat have it on the Southern African Wildcat and that most of those that actually have info on the Near Eastern one that is not in relation to the domestic cat are sites with info on a subpopulation of them called the Gordon’s Wildcat. The Near Eastern wildcat is closer to the domestic cat than to either the Southern African one or the other three subspecies, and taxonomists still insist on calling the domestic cat a separate subspecies or species.

    The wildcat species is listed as “Least Concern” on the ICUN List. The Chinese Mountain cat, the least widespread of the subspecies, is listed as “Vulnerable,” while the other four subspecies (the silvestris European clade, the lybica Near Eastern And Domestic clade, the cafra Southern African clade, and the ornata Central Asian clade) are listed as “Least Concern.” Of all the clades, the Lybica clade is the most widespread, even if you just included its “native” range and not its “introduced” range as well.

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