The Magic Weight of Coyotes and Pariah Dogs

From Scientific American comes an explanation why pariah dogs the world over are of a similar size and are particularly good at thriving under adversity:

“For mammalian carnivores, the 20-kilogram point, 20 to 21 kilograms, is the key here. Because mammalian predators that stay below that number can exist on prey smaller than them. And they’re often solitary or they only form small groups. And they can scavenge and be able to meet their energetic needs.

“But it they exceed 20 kilograms in body weight, now they have to eat prey that’s their size or larger to be able to maintain their energetic requirement. So they often are hunting prey larger than them, which requires often sociality. And so that’s why wolves rely a lot on deer, moose, elk, that they have to hunt cooperatively.

“Some of our coyotes get right to that 20-kilogram level, and that’s the perfect spot, because what they can do is they can either exist quite well on prey smaller than them, and that’s typically what they do, or if they have to, if the conditions dictate it, then they can hunt and consume prey larger than them. So they can do whatever they need to do. As opposed to the others, you’ll never see foxes taking down prey that are their size or larger, or rarely will you see that. And you won’t see wolves living off of really small prey, rodents, for any length of time, they will temporarily but not for a long time. So this kind of sets the stage for the perfect predator here.

“Also, being in the middle means that they are also subjected to predation at times by the larger predators such as wolves and mountain lions, and the occasional bear. So they have to be extra good at hunting their own prey as well as not becoming prey themselves. So it creates a super-smart animal.”