Ontario Backyard Food Web
Food chains, food webs … yes, Grade 4 Science it is. But do I remember how they work? Did we even learn how they actually affect us?
In trying to find some simple local examples of food webs I realized: no wonder nobody cares about supporting their backyard food web - it never involved us in the first place.
Your average 9 year old, at least in my day, was learning about the big wide world of eating things.
Plants “eat” sunlight, rabbits eat plants, foxes eat rabbits, wolves eat foxes, humans shoot wolves and so endeth the food chain. With us killing an animal without benefit to the food web or us. So why do we care if rabbits eat plants in the first place?
This, then, means we don’t care if those plants disappear, if that habitat is destroyed, because we were taught that it doesn’t make any difference to us at the top of the food chain. We eat vegetables we buy from the grocery store, not plants, silly ;)
Let us learn Science (not “the science”)
Welcome to the great outside world (Morning, from Peer Gynt playing in the background as birds sing.)
Spring Robins sprightly hop about the dewy lawn searching for their next meal of tasty earthworm. These earthworms (introduced from Europe) have been munching happily away on the leaf litter left over from fall. Watch as they turn it into rich soil (and apparently negatively impact our forest).
But wait! Who goes there?
A majestic Rough-legged Hawk swoops down and grabs our unsuspecting Robin, breakfast for her growing brood. After leaving them a tasty, but unsubstantial meal, she heads back out for more.
As she glides gracefully overhead, taking full advantage of the thermals, a large crack in the distance harkens her death knell.
The local chicken farmer has spoken. Her brood perishes. What is the exact trophic cascade of this event? We are not exactly sure. We know that hawks and wolves occupy similar places in their food chains (raptors are part of the balance). Could a hawk have the same local influence as the wolves?
Unfortunately, this is how humans have been taught to interact with the big wide world. Don’t ask questions. If it bothers you in any way just kill it.
But considering the wolves of Yellowstone, maybe we really do need to understand these interactions if we are going to attempt to manage them in a beneficial way, if we are to be true stewards of our land.
We’ll start at the very beginning
It’s a very good place to start.
You require energy to matter. You (biotic, living) require energy (abiotic, non-living).
E=mc2 and such.
In food webs, as in life, you have producers and consumers (Atlas Shrugged, anyone?).
Producers start out in soil and water, but let’s focus on the bigger, easy to see things, like plants and algae.
Producers gather and stockpile energy directly from the sun and nutrients from the soil or water. They can take abiotic elements from their surroundings and produce their own food, and stored energy.
Consumers cannot. They require something else to take abiotic elements and make them into usable energy, which is why humans cannot photosynthesize, we need to eat plants who photosynthesize for us.
But in order to photosynthesize those plants still need those abiotic elements to be found in the soil, they also need the required biotic elements that help them to thrive and reproduce, like pollinators.
It’s not just plant + in our mouth = energy from food.
For that plant to get to our mouth, and have the required nutrients, there is a whole web of other interactions in the soil and involving other living things. If we eat meat, for that animal to get those plants to get the required nutrients, again a whole web.
My Backyard Food Web
Let’s use the Tallgrass Prairie area that I’m planning for this Spring as an example.
I’ve tried to use bold and italics to help separate the different parts.
Producers: use the abiotic (non-living) elements in an ecosystem to produce their own food (energy)
Grass and flowers are producers; caterpillars, butterflies and other bugs are primary consumers; tree swallows (secondary consumers) eat on average 2000 flying bugs each, per day; and then our cute little Kestrel is the tertiary consumer when he eats them.
Primary consumers: Eat the Producer
Secondary consumers: Eat the Primary Consumer
Tertiary Consumers: Eat the Secondary Consumer
There can be more than three levels of consumption and each consumer can eat from any level really - there are carnivorous plants … and apparently carnivorous butterflies.
Producers (Primary consumer) ((Secondary Consumer)) (((Tertiary Consumer)))
Trees, shrubs and grasses - producing foliage, flowers, fruit and seed - are Producers
Let’s just focus on the Grasses:
Big Bluestem Grass -Producer
Caterpillars of several skippers feed on the foliage, including Atrytone logan (Delaware Skipper), Atrytonopsis hianna (Dusted Skipper), Hesperia leonardus (Leonard's Skipper), Hesperia metea (Cobweb Skipper), Hesperia ottoe (Ottoe Skipper), Hesperia sassacus (Indian Skipper), and Problema byssus (Byssus Skipper); katydids and leafhoppers also eat the leaves; Field Sparrow, Tree Sparrow, and Chipping Sparrow eat the seeds; Meadow Vole and Prairie Vole also eat the seeds
Caterpillars are eaten by birds, bats, frogs, mice, squirrels, even Black Bears have been found with 25,000 caterpillars in their poop, some insects parasitize caterpillars by laying their eggs in them like the Friendly Fly.
These birds, bats, frogs mice and squirrels go on to feed snakes, owls, hawks, foxes and coyotes.
Foliage eating bugs, caterpillars, butterflies, moths and bees are Primary Consumers
Indian Grass
Several species of grasshoppers feed on the foliage, preferred host plant of Eritettix simplex (Velvet-striped Grasshopper), Melanoplus confusus (Little Pasture Grasshopper), and Syrbula admirabilis (Handsome Grasshopper); Larvae of the Pepper-and-Salt Skipper Butterfly eat the leaves; habitat for Ring-necked Pheasant, Greater Prairie Chicken, Northern Bobwhite, Mourning Dove, and Field Sparrow
These grasshoppers are an important source of food to many insectivorous songbirds and upland gamebirds. The granivorous (grain- eating) birds are eaten by foxes, hawks and owls and their eggs may be eaten by snakes and racoons.
Grasshoppers are eaten by insect eating birds who can also feed hawks and owls and their eggs may be eaten by snakes and foxes.
Swallows, Warblers and Wrens eat insects making them Secondary Consumers
Switchgrass
Caterpillars of such skippers as Atrytone logan (Delaware Skipper), Hesperia leonardus (Leonard's Skipper), Hesperia sassacus (Indian Skipper), Poanes hobomok (Hobomok Skipper), Polites themistocles (Tawny-edged Skipper), and Wallengrenia egremet (Northern Broken-Dash) eat the foliage; a variety of birds, including wetland birds, upland gamebirds, and granivorous songbirds eat the seeds; seeds of these grasses are also eaten by the Prairie Deer Mouse and wild House Mouse
These grasshoppers are an important source of food to many insectivorous songbirds and upland gamebirds.
Who go on to feed hawks and owls and their eggs may be eaten by snakes and foxes.
Little Bluestem Grass
Caterpillars of several skippers feed on the foliage of Little Bluestem, including Atrytonopsis hianna (Dusted Skipper), Hesperia metea (Cobweb Skipper), Hesperia ottoe (Ottoe Skipper), Hesperia sassacus (Indian Skipper), Nastra lherminier (Swarthy Skipper), and Polites origenes (Crossline Skipper); Many grasshoppers also feed on the foliage; Field Sparrow, Tree Sparrow, Dark-eyed Junco, and other small songbirds eat the seeds
Grasshoppers are common in the same habitats as skippers and they are an important source of food for many insectivorous birds.
Who go on to feed hawks and owls and their eggs may be eaten by snakes and foxes.
Eagles, Owls and Hawks are all Tertiary Consumers
Where do I fit in?
All of these food chains/webs still end in animals, not us. So why should we care if there are enough coyotes or foxes near us? Why should we actually want them near us? Especially coyotes - they eat pets, right?
Actually not so much. Coyotes, what most people would consider the scariest top eater in these food webs, are an essential part of any ecosystem, even an urban one. Our negative interactions with them often has to do more with us mishandling the situation than them.
How do you feel about mice in your house?
Mice have on average 2-8 litters a year, of anywhere from 3-5 young, that can reproduce in 7-12 weeks and then the process starts all over again. So one Mommy mouse near you equals:
2-8 litters of 3-5 young or 6-40 babies in a year
We’ll say half are girls so that’s
3-20 reproducing females
Who then have
18-800 babies
Again, half are girls
9-400 reproducing females
Who then have
54-16,000 babies
Again half are girls
27-8,000 reproducing females
Who then have
162-320,000 babies
Then they take a 3 month break, and if they’re not dead, start again.
Fortunately for you, most don’t live longer than a year.
Why?
Snakes on average eat a mouse a week. Maybe that friendly Garter snake in the garden isn’t quite so gross anymore compared to mice in your house. But we can do better than one a week, especially if yours ate a frog or toad instead.
Hawk’s can eat 3 a day and foxes will polish off 8. Your average Owl will consume 12 mice in a night but that’s just breaking into double digits.
Coyotes on the other hand love small rodents and one coyote require 2-3 pounds of food a day. Taking the middle point of 2.5 pounds and your average mouse weighs in at 20 grams that means one coyote will take 56 mice out of that terrifying equation every single day. Or 20,440 mice out of that equation each year. Don’t you want them eating the mice before that number balloons into the millions in your backyard ;) I know, slight over exaggeration but hyperbole is used for a reason.
Other omnivores (Secondary or Tertiary Consumers) include, foxes, groundhogs, hares (yes, they eat meat), turtles, sparrows, woodpeckers, frogs, snakes and muskrats.
The main reason
We, as humans, are at the top of every food chain and food web in any ecosystem. Yes some animals are big enough to eat us, but they rarely get the chance.
More often than not we are the ones that are killing them, or destroying their habitat. But as we saw with the mice, taking tertiary consumers out of the ecosystem just because they are big, or considered scary or a threat, actually hurts us in the long run.
Everything in an ecosystem thrives because something else eats it, in moderation. If the numbers get out of whack then it affects every part of the ecosystem. Like the elk overgrazing willow on the riverbank in Yellowstone negatively impacted the river because the wolves have been removed, primary and secondary consumers can endanger producers and change habitat if tertiary consumers are removed from the equation. And we are the only ones who remove tertiary consumers in any number to matter.
Bugs, caterpillars and mice eat the grasses of my Tallgrass Prairie, they in turn are eaten by birds, bats and omnivorous animals and everything eventually decomposes back into the soil to feed the grasses.
Matter. Energy. Matter. Ad infinitum.
