Why the dog spread but the bear didn’t

When it comes to invasive species, there’s a paper somewhere on why they exist. To put it this way, when it comes to invasive species their spread’s inevitable yet it’s something that’s not only destructive to a native species but also something that can’t be easily resisted. Dogs for instance aren’t native to Africa, in fact they’re deliberately introduced there by humans and have spread to the rest of the continent. The brown bear on the other hand existed in North Africa but found itself extinct by the mid to late 19th century.

In terms of natural selection, if nature favours a species that’s good enough to survive there’s another that’s better at it and when it comes to phylogenetic diversity, the lower the phylogenetic diversity is the more invasive a certain species becomes. When it comes to lions, leopards and bears their numbers have been declining and while the leopard did adapt well to urban areas in India the same can’t be said of bears and lions so far as I know about it. If the bear’s numbers declined and the dog’s numbers increased, the latter would be more invasive and ecologically successful than the former is.

This means that both the cat and the dog are very successful at colonising Africa and Europe, especially when there’s declining phylogenetic diversity. The numbers of gorillas, bears and lions have declined in Africa but the numbers of dogs and cats rose despite culling, this makes the two a proper super competitor and invasive species.

Invasive Species of Africa

When it comes to invasive species in Africa, it’s pretty much any introduced species that has a detrimental effect on native wildlife whether through competition, predation or spread of diseases. Dogs might be a good example of an invasive species in Africa since out of all the canids only the dog’s not native to Africa being introduced from Israel and the Arabian peninsula (which’s also how Islam, Christianity and Judaism as well as the Afro-Asiatic languages spread). One way of knowing that they’re an invasive species is their effects on primate populations in Morocco (Barbary macaques) and Uganda (Vervet monkeys).

In fact, there are two studies of dogs preying on Vervet monkeys in Uganda. Another invasive species is the cat, though there’s only one study on their impact on Cameroonian amphibians so far. This is a bit trickier than dogs in that cats were domesticated twice, once in Anatolia and once in Africa via Egypt so in some sense they’re native there in both. To put it this way, if dogs are native to Asia why are they considered an invasive species? They’re harmful to civets in Hong Kong, sea turtles in the Philippines, various species in the South Asian subcontinent and Israel and antelope in Mongolia and in Tibet, China.

So there’s your answer, though there’s another study or two in Cameroon on the predation of guinea pigs by both cats and dogs so this sheds light on them as invasive predators.

Dogs as an invasive species

I think I brought this up before but it does bear repeating when it comes to people’s near ignorance of this subject matter: dogs are an invasive species and have killed animals themselves. There are studies that show dogs as efficient predators of wildlife such as pudu and fallow deer. There are many news reports of dogs hunting roe deer and sometimes ibexes. This is enough to warrant a study in Spain and suspicion from hunters, as far as I remember and know about it. Another way of knowing that dogs are an invasive species is when they disrupt the environment of native birds, which’s stated in one study.

When it comes to awareness of dog predation, there are those who do take it seriously but not enough to override people’s perceptions as far as I’ve experienced. When it comes to dogs having a prey drive, one of my dogs ate and killed frogs and another ate a skink. My cousin’s dogs have killed rats. While not all dogs necessarily have a prey drive, it’s also true that many dogs can and do hunt wildlife on their own if reports of dogs straying and hunting deer are any indication. There’s even a study in Poland showing that dogs do prey on wildlife on their own.

That’s one of the ways they’re an invasive species and why more people should take it seriously.

Ferrets as an invasive species

Ferrets are mustelids that are used for hunting rabbits but in some countries (Ireland and New Zealand so far) they’ve turned into an invasive species there. That’s if or rather when they don’t have a lot of natural predators in these two islands that they proliferate and hunt native wildlife there. Ferrets were introduced in New Zealand sometime in the 1870s or something to hunt rabbits but became a pest there alongside stoats and weasels. If Australia’s war with foxes is any indication, any attempts at eradicating rabbits with a nonnative predator has the latter become an invasive species itself.

That’s true for Ireland where ferrets were introduced for a similar purpose but ended up proliferating in the wild and hunting down endangered species themselves. Now supposing if ferrets were introduced to say the Philippines and Nigeria, that’s going to cost millions and more than a billion naira and Philippine pesos spent on culling ferret populations. You might say that there are predators in Nigeria that might keep ferret populations in check, but since those animals are becoming highly endangered that ferrets would proliferate there and have the upper hand.

Same thing would happen if foxes were introduced to Nigeria and the Philippines. When it comes to an invasive species like ferrets, they ought not to be underestimated as they can wreck wildlife and make governments lose billions of money. New Zealand has already lost animals to ferrets, same thing in Ireland that I think people need to think twice about introducing ferrets there. Not to mention New Zealand has the largest population of ferret-polecat hybrids and banned their ownership or something which shows you how bad their ecological impact is.

If you want to own ferrets then that’s fine with me, but then again ferrets have caused ecological problems in New Zealand and Ireland such as predation that their governments are doing something about this and the fact that they don’t have a lot of natural predators there make it easy to proliferate there.

Dogs, the original invasive animal

As of now, dogs are currently ranked as the third most destructive invasive animal as revealed in an Indian study though it has been suspected before in other studies. If dog domestication came before cat domestication, it’s only logical and realistic that dogs would be the first invasive animal or at least one of the earliest. There are case studies and reports of dogs hunting wildlife such as seals, deer and wild asses as well as mating with wolves that they not only negatively impact the ecosystem but also risk diluting the DNA of the latter animal. If invasive species are introduced, it makes sense that dogs would constitute an invasive species in the entire continent of Africa as they’re not native there and would’ve been introduced from Western Asia.

Dogs are probably the only canid not native to Africa so if they come from the Arabian peninsula, that only proves my point right. One way of knowing how bad they can be to wildlife in Africa is through case studies done on their habit of harassing Barbary macaques in Morocco and vervet monkeys in Uganda. There’s also another case study of a dog preying on a long-tailed macaque in Singapore, so even if the dog was first domesticated in Asia it’s still an invasive species if it negatively impacts wildlife. Not just through predation but also spread of disease in some cases as well. It would be parsimonious to say dog predation could’ve occurred in prehistoric times, if studies on dogs in one hunter-gatherer society’s any indication.

You could argue about cats doing the same thing in ancient societies but since dogs came first, they’d have the dubious honour of being one of the earliest invasive animals in the planet, next to mice. A distrust of dogs was apparent in some ancient texts such as the Old Testament so dog predation could’ve existed back then as well that proves my point right.

Making of an invasive species

An invasive species is any organism that becomes overpopulated and negatively impacts the environment as according to Wikipedia, sometimes by predation and sometimes by spreading diseases. When it comes to animals, it would be parsimonious and provocative to say that dogs aren’t just the first domesticated animal but also the first invasive animal at that. If you have dogs hunting on animals such as antelope in Mongolia, blue sheep in China and wild ass in India then that’s not only predation but also negatively impacting the environment especially if they’re endangered that dogs would be the first invasive carnivore.

Another reason why they’d be the first invasive carnivore and animal’s that cats have yet to reach outside of Africa and Anatolia in those days, if cats weren’t mentioned in Ancient Greek, Chinese and Indian texts then it shows they wouldn’t arrive there yet and cats would constitute as the second wave of invasive animals after dogs, pigs and mice. If dogs aren’t native to Africa and probably descend from Middle Eastern dogs, in addition to being invasive predators to Barbary macaques in Morocco and vervet monkeys in Uganda then they’d qualify as an invasive species there too.

Cats wouldn’t be domesticated until around 10,000 BC, centuries after dogs were domesticated (if they’re first domesticated in 14,200 BC) so they’d be part of the second wave of invasive animals after dogs, mice and pigs. Pigs, mice and dogs constitute the first wave since they were around 15,000 to 12,000 years ago with mice and dogs being the earliest invasive animals wrecking havoc on native wildlife whilst leading commensal lives with humans though it could also be said of pigs to some extent as well.

Cats, goats, sheep, rats and cattle would constitute the second wave of domestic animals with cats and goats being the second wave of invasive animals, especially with regards to their ecological impact on native wildlife. Cats preying on animals, goats eating endangered plants and rats doing both in addition to spreading diseases. I would say second wave as their domestication and spread occurred centuries after the domestication and spread of dogs, mice and pigs. There were even fancy rats in Japan sometime in the 17th century, which shows how far and early they’ve spread.

Rabbits and ferrets would constitute the third wave of invasive species and domestic animals, centuries after cats were domesticated and in the case with these two they’ve hurt and decimated native wildlife in New Zealand. In fact, ferret ownership’s restricted in New Zealand to keep them from preying on other animals. Rabbits are also a pest in Australia where there are attempts at curbing their populations through viruses. Rabbits may not be the last animal to be domesticated but they’re part of the third wave of invasive species along with the ferret.

Mongooses, foxes and cane toads would constitute the fourth and fifth waves of invasive species since mongooses did have a long history of being used as pest control and foxes were used for fur as early as the Middle Ages but only became invasive species in select countries fairly recently. Same with the cane toad which’s invasive in the Philippines and Australia. I might have to write a book on invasive species if I wanted to and return to this subject matter, maybe revising it with a bit more detail but that’s all I know about invasive species.