From a friend’s wall:
Its a cute meme. It gets some things correct. Ravens are commonly associated with wolves. They may even like them. We can’t really know. What we do know about ravens though, is that they are carrion eaters. This fact probably better explains their association with wolves than merely liking wolves (which again, they may really, really like wolves). Ravens however do associate with a large number of predatory species.
Ravens and a very handsome fox
from the White Wolf Pack blog
Ravens and Grizzly Bears at a Bison carcass
Raven’s have also had a long association with human warfare. Ravens and other carrion birds are common features of histories of war in the times when men fought and died shield to shield, by spear and by sword. This association has long made the raven (a species with a cosmopolitan distribution and many subspecies) a prominent figure in human mythology. Despite this, few people are willing to posit a great deal of affection flowing from ravens toward humans.
The ecologist Bernd Heinrich’s work with ravens has revealed a great deal about their associations with apex predators. In two wonderful books, Ravens in Winter, and The Mind of the Raven Heinrich discusses many years worth of research on ravens. Raven ecology is generally fascinating but germane to this post, is the interesting mutualism that ravens seem to enjoy with apex predators.
Ravens follow wolves and other predators around because it is the surest path to a meal. If you are raven and you want to eat an elk, you are going to need an intermediary to help get that meal. Ravens use apex predators to open up elk, bison, moose, and numerous other animals that ravens just can’t kill for themselves. Associating with apex predators means that ravens don’t have to wait for something to fall over and die before they can eat. A moose is going to die, that is just the way of nature. Ravens have noticed that apex predators form a catalyst for the death reaction.
An immediate question may occur to readers though. Why do wolves and other apex predators put up with ravens. Having ravens at your table (there can be 5-20 ravens at moose kills on Isle Royale) is actually, from the perspective of the predator, incredibly costly. Researchers at Isle Royale, have noticed that ravens abscond with up to 40% of moose meat from kills on the island. The researchers at Isle Royale (one of the longest continuous studies of predator/prey interactions in the world) were trying to understand why wolves traveled in packs. Part of the answer may be, for wolves that hunt big game anyway, that groups of wolves get more meat from a kill than ravens. Smaller packs lose more resources to raves than do larger packs. Losing meat to closely related pack mates versus completely unrelated ravens probably translates to more copies of one’s own genes being levered in to future generations. A wolf can expect to share many genes with it pack mates and none with ravens. There is a Hamiltonian rabbit hole we could go down here, but lets save that for another post. The researchers at Isle Royale think pack size may be way to defend, or at least more efficiently utilize prey items. More wolves means fewer ravens on the kill at any one time. The researchers noted that larger packs translated to more meat per individual wolf at a kill than for smaller packs.
Another part of the answer to why apex predators put up with the competition from scavengers like ravens may be that any apex predator can only eat so much at a meal. Wolves, for instance, can consume a lot per meal (about twenty pounds in a sitting) but 10 wolves eating a moose will only get 200 pounds, or about 20% of moose meat. Wolves could certainly try defending a kill, but easy meat will quickly become scarce on the carcass, and returns will diminish. All apex predators will have some limit on what they can consume in a sitting, so loss of even a large percentage to ravens won’t really matter.
Still, putting up with competitors at a kill seems profoundly non-Darwinian. There are no free rides as it were, and we would expect that if the behavior pattern exists, perhaps it confers some advantage to the predators to put up with the ravens piggy backing on all that predatory effort. The work of Heinrich and others seems to demonstrate that ravens actually contribute to the apex predator’s meal plan. There is a lot of strong evidence that ravens act a lot like Honeyguides.
The Greater Honeyguide
Honeyguides are highly specialized African woodpeckers that can metabolize wax. Honeyguides eat honey, wax, and bee larva. The problem is they can’t really open up beehives. They have hit upon the novel solution of getting humans and honey badgers to do that for them. They lead humans or honey badgers to beehives, wait for their biological tool to open the hive and then eat.
In his book Ravens in Winter, Heinrich documents raven calls drawing in larger predators to open up frozen carcasses with claws and teeth. Frozen carcasses pose a large problem for a carrion bird equipped with only a bill (stout to be sure), small claws and wings. Recruiting another animal to help process the frozen carrion means sharing valuable resources, but not sharing would mean not eating. Natural selection processes probably favored ravens who made a lot of noise at frozen carcasses over those that did not (one group leaving more descendants than the other is winning evolutionarily).
Wolves are likely not the only apex predators to have learned to listen to the ravens. Two vignettes from Heinrich’s The Mind of the Raven, may underscore this point. In the first vignette we find Inuit hunters. When hunting polar bear, Inuit hunters draw their prey in by making raven calls. Raven calls reliably attract polar bears. What holds for human tricksters, may also hold for raven tricksters. Ravens calls in the wild probably attract polar bears too.
The other vignette, more chilling, but also kind of cool, involves a raven acting -possibly- like a Greater Honeyguide, and leading an apex predator to something to kill. In this case the prey was an old woman who had straggled a bit behind her husband on their hike. As she worked to catch up to her husband, she had a raven persistently behind her on the trail, calling its peculiar, call. She thought she had made a friend, but upon turning around to examine her new “friend” she noticed a new hiker on the trail. Approaching her in that predatory crawl that is the frightening hallmark of cats everywhere, was a puma. Fortunately for her, as the puma approached, at speed, her husband came crashing down the path from the other direction. Seeing the big man, and his big stick, the puma beat a retreat. Wary prey makes for wary ambush predators.
The raven also exited the scene.
“But I just want to be your very last friend!"
That last vignette could be interpreted several ways. Perhaps the raven was warning the old woman about the feline danger that was approaching. Perhaps the raven had precisely no interest in the drama that was unfolding on the trail. Perhaps it was Huginn or Muninn on some cosmic errand? Heinrich suspected not. His work with ravens, along with the work of others, suggested to him a darker motive on the part of the raven, one that sought to put an old woman on the dinner plate.
So do ravens like wolves? Maybe they do, but nature is complex and our human psychology may not be entirely predictive of the emotional lives of wild animals who have their own suite of concerns. A better explanation for the image in the meme, can be found in the ecology of ravens.
Ravens eat carrion. Wolves and other apex predators generate carrion.
