Thursday, May 25, 2017

Why Do Dogs Eat Grass?

Why do dogs eat grass?

It's a common question, but in asking the question, an assumption is revealed.

The assumption is that dogs are not supposed to eat grass.

After all, no one asks why we humans eat chicken, corn on the cob, fish, or strawberries.

The short answer is that dogs eat grass because it tastes good and it provides some nutrition.

It is not a sign of worms, an upset stomach, or any kind of nutritional deficit.

That's the short answer.

Now let's look at the question a bit deeper.

Do wolves, fox, coyotes, and dingoes, also eat vegetable matter?

The answer is "yes."

Wolf biologist David Mech notes that grass appears in 14-43% of all wolf scat found in North America and Eurasia. Plant material in fox and coyote scat, including grass, is so common as to be unremarkable.

Leopards, jaguars, mountain lions, and bobcats also eat surprising amounts of grass. A sample of 215 leopard scats collected in the Tai National Forest of the Ivory Coast, for example, found 17% had a considerable amount of grassy vegetable matter.

Bears too eat a lot of plant material. Though classified as the largest carnivores in the world, bears eat more vegetable matter in their diet than flesh, and grass is a major food source.

So why do "carnivores" so often eat grass?

For the same reason you and I eat most of the foods we eat; it tastes good.

Of course the other answer is that it is maladaptive for them not to do so.

Let's explore that idea a bit more.

Specialization in food sources is a terrific idea so long as the world stays exactly the same, day in and day out, season after season, year in and year out.

But, the world is both temperamental and unreliable.

Crippling winters, blistering summers, and poorly timed rains can decimate populations of prey species.

Disease can wipe out herds, migration routes can change without warming, and new species can invade.

Water holes may dry up, salt licks may disappear, and predators can injure themselves in the chase.

And yet every few days, a predator must eat.

And that's the problem: The chain of life is so easily snapped.

For a meat-eating predator, the weakest link is the absence of ready prey, easily caught, day in and day out, in good health and bad, dry season and wet, winter and summer, year after year.

And so wolves, coyotes, dingoes, bears, lions, bobcats and jaguars have all evolved to eat plants, as well as flesh -- a way of "hedging the bet" for a few days against the vicissitudes of life.

Yes these animals will try to bring down a deer- or rabbit-sized meal if they can. But if they cannot, then they will try to catch a few rats or mice, a lizard or a snake, a frog or a turtle.

And if push comes to shove, there's always grasshoppers, crickets, and verdant grass along the creek. And it does not hurt at all that some of that grass actually tastes pretty good!


Mongoose said...

I think TV does a lot to sustain the misconception that big carnivores only eat big herbivores. They show you a snow leopard chasing something and failing and they go "her cub will not eat today." Huh? Her cub will eat everything that moves, of course. Mice are way easier to catch than mountain goat and they're nutritious. My dog used to eat so many mice she didn't even touch her food dish and she was getting fatter and fatter. And yet, you never see a big carnivore eating a mouse on TV.

stonesoupdiaries said...

Dogs love new grass. I tend to let the resident dogs out into the lower pasture after a mow and they all drop their heads like cattle and start grazing away.

Never an upset stomach in the lot of them.

I am half expecting them to moo any day now.

Out of curiosity, I tried it once and found that it tastes much like the sweet shoots of new corn after it has sprouted.

Once the 'new' has worn off, they lose interest in the older, more mature grasses of the marsh or the lower pasture about June.

Rarely does it come out undigested, but I have had a dog or two that ate so much they were passing it somewhat whole.

Viatecio said...

Linda basically summed it up for me.

My issue is, when does it become an obsessive thing? There are times when my dog will just foresake everything else and do nothing but graze. Rarely comes out undigested/whole and is never puked up, just...that's all she does sometimes, and it's not like she's really that bored, it seems.

That really was a great article though. Makes you wonder how much cellulose material in corn gets digested, if grass never comes out whole!

Bartimaeus said...

To judge by the coyote scat around my neck of the woods, juniper berries form a significant part of their diet this time of year. It will gradually get grass, then fur, and then grasshopper exoskeletons as the summer wears on, but right now all the fresh coyote scat is full of juniper seed.

Fall Charmz said...

thx for linking this in a recent post - we were just wondering about this when we see our Lab snack on grass.

Noel said...

My Border eats sawgrass, then hacks relentlessly when it sticks in his throat. It must be delicious. Or he's an idiot. Jury's out.

Shannon Gentry said...

My Border prefers cleavers over the grass, altho he will still snack on grass.

Sarah Bishop said...

My cattle dog grazed a lot. I frequently reminded her that cattle dog did not translate as being a cow. She rarely vomited it up and I simply chalked it up to a quirk of her nature. Especially since she was a weird dog overall.

JL said...

I have seen my dogs rush outside to start snatching at grass. The resulting vomiting seems to have been the goal of the grass ingestion. It's usually coarser, harsher grass at those times, as compared to their more measured eating of finer grasses at other times. First spring grass is desirable eating, and the first grass when it greens up after the summer dry/die back.

geonni banner said...

I read somewhere (David Mech?)that one of the first things wolves eat when they pull down a large herbivore is the contents of its stomach.

My dog also prefers new grass. But she will also eat coarse, scratchy mature foxtail grass up until it turns yellow.

I once had a Doberman that not only ate grass, but relished blackberries. I would come out into the back yard and find her standing on her hind feet, forepaws tucked daintily against her chest, grazing berries. She only ate the ripe ones.

PBurns said...

Wolves are opportunists. Their preferred food is whatever is easy and loaded with fat -- same as us. If a wolf kills a rabbit, it will probably eat it whole, while if it kills a deer, it will go for the stomach, liver, belly fat, and heart. Wolves are not always found in wilderness. Mech notes that:

"In parts of Eurasia, wolves live in areas with relatively little wild prey, but subsist nevertheless on a wide variety of foods provided indirectly by humans. Foraging in garbage dumps, wolves eat meat scraps and various fruits, as well as inadvertently consuming non-food debris. In Israel, the following items were found in wolf scat: human hair, plastic, tinfoil, cigarettes, matches, and egg shells. In Minnesota, long sharp shards of glass were found in Scott's of garbage dump feeding wolves."

You know what they feed the wolves in zoos? Dog food! See

"Feeding requirements of red wolves have generally not been a problem in the RWSSP, as long as good quality commercial (dry) dog food is provided. Because of the number of commercial foods made, their availability, and cost it is difficult to recommend a specific brand. Wolves maintained in
Tacoma have done well on food with label guarantees ranging from 22-28% protein, 8-18% fat, and 2-4% fiber. Vitamin supplements for red wolves are normally not required. Adding commercial carnivore log to dry chow may be needed to encourage some wolves to eat, although should not be the primary component of their feed."