Pack of African wild dogs. (Photo by Bart Swanson.)
Canidae, otherwise known as the dog family, is one of the most highly adaptable carnivore families out there, with an array of body forms and behavioral adaptations. From the three-pound fennec fox to the gray wolf, which can weigh upwards of 130 pounds, there are 34 living species of canids.
I plan to do a series of individual articles on the behavior and life habits of different canids, but for now let’s have an overview of how the group evolved and what sets them apart from other carnivorous mammals.
I’ll also discuss- briefly- the misconceptions of canid social behavior present in popular media.
The Evolution of Canidae
Canids are members of the order Carnivora, which contains two major suborders: Feliforms, including cats, mongooses, and hyenas, and caniforms, which includes seals, weasels, bears, and, of course, the dog family Canidae.
The oldest true canid genus that we’ve yet discovered was Prohesperocyon, about 40 million years ago. These guys were about cat-sized and probably lived in the forest, but they were beginning to show the longer limbs and closely-arranged toes characteristic of modern canids.
From early canids like Prohesperocyon, three subfamilies developed: Hesperocyonidae, Borophaginae, and Caninae. Hesperocyonidae were small fellows that tended towards scavenging or pack hunting, while Borophaginae produced some of the largest canids to ever live, equipped with bone-crushing jaws like a hyena.
But both of those lineages are now completely extinct, possibly because both tended to get larger and more hypercarnivorous. Smaller omnivorous species tend to be better survivors over the long term than large meat-eaters. We can see this sort of pattern today in the dhole and African wild dog, two modern hypercarnivores that have struggled to rebound after human hunting drastically reduced their numbers.
Caninae had the advantage of even longer, more slender legs and a reduction of the fifth toe on each foot. This made them even more suited for running, leading up to the large cursorial hunters that exist within the family today.
In this photo on the left you can clearly see the specialized dog paw: the toes are placed close together, with the fifth dewclaw protruding above. The area of skin on the dog’s wrist is called the carpal pad. (Photo by Bas Lammers.) On the right is a bear paw for comparison. (Photo by Petruss.)
Modern canids have their roots in North America, with the most basal species, the gray fox, likely resembling those early members of Caninae. From there they split into two major tribes, Vulpini and Canini. Vulpini contained the members of Vulpes (the true foxes) as well as the bat-eared fox and the raccoon dog, while Canini further split into two more groups. The South American canids, including the false foxes or zorros, colonized South America, while the wolf-like canids, including the jackals, wolves, and hunting dogs, developed for some time in Africa before spreading back out across many continents.
Examples of the three major groups of canidae. Kit fox from the fox-like group; black-backed jackal from the wolf-like group (photo by Hans Hillewaert); Darwin’s fox from the South American group.
The exact organization of the living canid phylogeny has long been contested in the scientific literature. This is due to its relatively recent radiation (modern canids appeared 10 million years ago) and the close genetic similarities between all members.
The version I’ve seen used in textbooks as recently as 2012 (though it came out in 2005) is below.
Purple: Basal species. Red: fox-like canids. Yellow: wolf-like canids. Green: South American canids. (Click for a larger view.)
Alternatively, a newer phylogeny was developed in 2012 by a pair of German scientists who combined older data with new analyses of genetic data.
The most intriguing difference between the two phylogenies is the placement of the African wild dog and the bush dog. While the older phylogeny and most older phylogenies with it place the bush dog as the closest living relative of the maned wolf, the new phylogeny puts it as the closest living relative of the African wild dog an ocean away.
Left: bush dog (photo by Tony Hisgett). Right: African wild dog (photo by Michael Gäbler).
Despite the physical distance, the two species have several behavioral and physical characteristics in common, the most notable of which is a specialized cutting tooth called a trenchant heel. This makes the change feel more parsimonious.
However, a third species, the dhole, also has the trenchant heel, and the new phylogeny puts it further away from the African wild dog. The trait would have had to have disappeared in the side-striped and black-backed jackal lineages and then reappeared in the dhole.
Ultimately it seems as though the canid family tree will keep getting refined as research progresses.
Canid Lifestyles
The majority of canids are dietary non-specialists, foxlike scavengers that make their living off whatever they can find. Almost all of them are omnivorous, with plant matter making up varying percentages of their diet. For example, early attempts to exhibit maned wolves in zoos went poorly until they realized that about 50% of its diet actually consisted of fruit and plant material.
There are also slightly weirder dietary choices amongst canids. The bat-eared fox, for instance, subsists almost entirely on termites. Blanford’s fox also enjoys insects, as well as fruit, with very little red meat on its menu. The Ethiopian wolf, a species just a bit larger than a coyote, almost exclusively eats big-headed mole rats.
On the flip side, there are the aforementioned trenchant heel species: the dhole, the African wild dog, and the bush dog. These three species are obligate carnivores like the big cats, eating meat and only meat, using their specialized shearing teeth to slice it away from bone.
A canid’s diet type also reflects its social lifestyle. The least specialized canids tend to be the ones with looser social groups, though all canids do- at some point in their lives- live in social groups.
The basic canid group unit consists of two socially monogamous parents and their juvenile offspring, and some of the most complicated can consist of extended families- aunts and uncles and even more than one breeding pair. I’ve provided diagrams of some- not all- of the canid family structures that can exist.
Some examples of each type. A: maned wolf, raccoon dog, crab-eating fox, coyote. B: gray wolf, red fox, coyote. C: bat-eared fox, swift fox. D: red fox, bat-eared fox. E: gray wolf, dhole, African wild dog. F: dhole, African wild dog.
You may notice that some of the examples I listed above fall into more than one social category. That is because many canid species are flexible with their social styles depending on what resources are available to them in their environment.
The basic monogamous pair forms due to the fact that canine offspring require a lot of care at birth, and many species give birth to large litters. Smaller omnivorous species may also have a hard time bringing adequate amounts of food to their young with just one parent. The raccoon dog takes the longest time to nurse its pups out of any canid because its food items are so small and it cannot regurgitate food for its young.
Canids with large body sizes tend to be more carnivorous than canids with small body sizes due to the energy requirements needed to survive, and the pack hunters are among the largest canids- excepting, of course, the bush dog, which only weighs 15 pounds or so. The gray wolf, the African wild dog, and the dhole make up the other pack hunters, and live in the largest groups. The African wild dog and the dhole in particular are capable of forming massive packs of 30 or more individuals.
Their normative social unit is formed by separate female and male lines. Females disperse from their natal packs with their sisters and males do likewise with their brothers, so that when two groups meet up the females and males are all unrelated to one another. Despite this, most of the time only one male and one female in each group breed.
These species require these huge packs because they have very large litters (sometimes up to 16 puppies) and hunt prey much larger than themselves. Another factor may be that both the dhole and the African wild dog live in ecosystems where there are predators much larger than themselves, and without numbers on their side they would frequently be victims of kleptoparasitism (having their kill stolen).
But pack hunters are not the only canids that live in extended family groups- canids with more specialized diets tend to do this as well. Both the bat-eared fox and the Ethiopian wolf live on specialized prey that form large colonies: termites and big-headed mole rats, respectively. Because their food is concentrated in large clumps (termite mounds or mole rat nests) their environment can support multiple group members over a small area. These clumped resources mean that these species also become more territorial and large groups may help in defense from other families of their own kind.
Socially monogamous species are usually those that employ male parental care, and canids are no exception. Male parental care evolves when the number of the male’s offspring that he fathers and helps that survive to adulthood is greater than the number of offspring he fathers with multiple females (and doesn’t help) that survive to adulthood. This makes it more valuable for him to nurture than be promiscuous.
Nearly all male canids show some form of male parental care, which usually consists of guarding and watching over the pups while mom feeds herself, and helping feed mom. The bat-eared fox is one of the most exemplary canid fathers and almost completely takes over caring for his children from the mother once they are weaned.
A bat-eared fox pile.
Species that live in very large groups like wolves, dholes, and African wild dogs will often employ “babysitters” of either sex from their adult offspring for their juvenile offspring.
Just because canid species are socially monogamous, however, does not mean that they are always sexually monogamous. Not very many studies have been done on the fidelity of canids; however, cheating seems to be more prevalent among the highly social species where more mates are constantly available. An example of this is within African wild dogs: a small percentage of most of the breeding female’s litters tend to be from extrapair matings. (Like cats, canids can have litters with multiple fathers.)
In red foxes and other smaller species, there are more overt forms of polyamory: with a rich enough territory, a male fox may be able to support two females and their offspring. Conversely, among Ethiopian wolves, which have a small population with very limited territorial spaces, extrapair relationships seem to be a necessity to avoid inbreeding.
High resource availability may also lead to multiple breeding pairs in the pack-hunting species like gray wolves. In cases where there is little starvation pressure on the dominant breeding female’s own pups, she may allow a subordinate female to keep hers. This is helped by the fact that subordinate females are almost always either her sisters or daughters, meaning that she gains an inclusive fitness benefit because they have genes in common. (The alternative, of course, is that she kills the pups.)
You may have noticed that this is the first time I have used the words “dominant” and “subordinate” in this discussion of canid social lifestyles. That is because this application is one of the few times when they are appropriate to use with canid lifestyles. Most tiered relationships within the canids exist between parents and their adult offspring, in which the adults are naturally dominant. And offspring tend to disperse when they are ready to mate rather than challenge their parents for the “dominant” spot- the alternative would be to mate with their parent or sibling!
The exceptions fall in species where there are male and female lines rather than only parents and their offspring, meaning that each female is unrelated to each male, or in groups where adult offspring are forced to stay with their parents long after sexual maturity. However, even in these cases, dominance is less expressed in agonistic displays from higher-ranking individuals than it is expressed in submissive behaviors from subordinate individuals.
Much to the aggravation of ethologists everywhere, popular culture still clings to the mistaken idea of the “alpha wolf”- that of a fierce male wolf that has fought his way to the top and holds his spot with displays of aggression. It’s fairly far from the truth, even though it originated in scientific literature. The problem was that the studies that originally documented these “alpha” behaviors- from the 1940s, mind you!- were based on unrelated captive wolves that were essentially thrown together. Nothing could be farther from the natural wolf family, and of course there was a high amount of intragroup aggression.
The idea was not corrected in the scientific community until the early 90s, and by then the damage was done; pop culture had caught hold of the concept and would not let go. Over twenty years later, I still cringe when I see such-and-such werewolf show full of alpha this and alpha that and such and such televised dog trainer advocating the idea that you should physically dominate your dog.
Canid social groups are families. They don’t subsist on aggression.
Of course, there is one group of canids that is not socially monogamous, nor does it form its own stable family groups. That is the domestic dog, a subspecies of the gray wolf, as well as its close relatives the dingo and the New Guinea singing dog. While research on stray, feral, and pariah dogs is still limited, it seems that females raise their pups alone. It is hard to tell much else about group structure because most stray dog groups are not stable: individuals are dying and being replaced at high rates and usually still depend on humans for their food. Loose hierarchies exist, but many strays live in groups where they are not closely related to one another because of this swift turnover.
I plan to do an article specifically on the limited research that has been done on free-ranging stray dogs, as well as their completely wild relatives the dingo and the New Guinea singing dog, but in general it seems that a dog’s ‘natural’ behavior is not what you observe it doing without humans present. The domestic dog has coevolved with humans for tens of thousands of years, and it is now part of our family, treating us like its very own hairless parents.
Read on: Check out my original story about some members of the canid called Darkeye. You can also learn more about another animal family- bats- at my Introduction to Chiroptera post. I can also tell you why small dogs live longer than big dogs. To understand why adult domestic dogs act like goofy puppies, check out my post on heterochrony!
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