Native plants key to attracting birds and other predators
The relationship between our garden predators, including backyard birds, and the use of native plants is tied together by the insect herbivores that depend on native plants as a food source. Together the predators, prey and native plants work to keep our gardens in harmony.
Birds need insects and caterpillars to survive
When we think of predators in our Woodland Wildlife gardens the first thing that comes to mind are larger animals – coyotes, foxes, hawks, owls maybe even snakes large and small.
In other words, we often think of predators with a little trepidation that almost always involve animals with big, sharp teeth, or large and powerful claws.
But the reality is that most of our garden predators are either our favourite birds – chickadees, warblers, cardinals and indigo buntings – or tiny creatures often referred to as beneficial insects that we might not even know live in our gardens.
What do they all have in common? They all require a source of protein that is mostly derived in some part by insect herbivores able to convert specific plants into food for predators.
But not all plants – almost always those plants are native plants, shrubs and trees.
A three-tier approach to predators
These predators can be broken into three tiers: Dominant ones like foxes, hawks and owls, followed by second-tier predators (birds, smaller mammals, amphibians and reptiles) and finally third-tier predators made up mostly of predatory insects and larvae.
So many homeowners have serious pest problems because their gardens are not welcoming to the predators and parasites that in natural ecosystems help keep infestations in check. It’s important to note that if we want to encourage a garden in harmony – critical to keep our gardens from getting overrun with caterpillars, mice and rats – we need to focus on providing a food source for all predators and their prey.
A yellow warbler searches tall grass in search of prey. Backyard birds are among the most voracious of predators in our woodland wildlife gardens.
To put it simply, if a natural area is working in harmony, it’s the predators that are keeping everything in check.
For example, the bottom tier of predators (insects, spiders) are often eaten by the middle-tier predators (birds reptiles) who are often eaten by the top-tier predators. But all the predators are dependent in some way on the herbivores that primarily get their sustenance from plants.
Without these multi-tier predators, our gardens would quickly be over run with insect herbivores, but without them, we would have no predators and that includes birds.
Let’s call it the garden food chain.
The bottom tier of predators is where it begins
So what makes up the bottom tier and how can we invite these predators like beneficial insects into our gardens?
Think the larvae of the delicate green lacewing, a host of beetles, daddy longlegs, small parasitical wasps and tachinid flies, dragonflies and a host of garden spiders that either spin webs or hide out on our flowers ready to pounce on smaller insects all the while helping to keep our plants free from destructive infestations. Many of the best garden predators are actually larvae of larger insects, others are parasitical larvae that develop on or within a victim, ultimately killing it.
As a bonus, these lower-tier predators can also be a fascinating new world of insects to discover and photograph in your garden.
Ask yourself if you are eliminating the lowest tier predators and their prey (caterpillars and other insect herbivores) through the use of pesticides? Or is our overly tidy garden leaving little room for these predators and prey to complete their life cycles? Both can be a death sentence for predator and prey.
“I cannot overemphasize how important insect herbivores are to the health of all terrestrial ecosystems. Worldwide, 37 per cent of animal species are herbivorous insects. These species are collectively very good at converting plant tissue to all types of insect tissue, and as a consequence they also excel at providing food – in the form of themselves – for other species. In fact, a large percentage of the world’s fauna depends entirely on insects to access the energy stored in plants. Birds are a particularly good example of such organisms,”
Just last spring, I was visited from an ill-informed young fellow representing a company saying it would spray around our home to eliminate insects. When I pushed back, he added with great conviction that they would also kill all the spiders around the home’s foundation to ensure a spider-free home. That only raised my blood pressure another notch.
He also assured me many of my neighbours had already purchased the service. A sad commentary on the lack of awareness among so many homeowners.
Please, lay off the pesticides. You may have to tolerate some minor infestations if you turn to beneficial insects and parasites to keep your garden in check, but remember that normal populations of “bad guys” are a necessary food source for the beneficials and help keep them in your yard.
It’s a small price to pay for a healthy garden.
Native plants are food for both prey and predators
Once we eliminate pesticides and an overly tidy garden, it’s important to focus on providing the prey with food to attract them to the garden and, in turn, provide predators with a healthy source of food.
The best way to achieve this is through the use of as many native plants as possible. These are plants that have been part of our natural ecosystem for centuries, and plants that our indigenous insects and animals have grown up with for thousands of years.
Unfortunately, many of these plants have become known as weeds to gardeners and lawn companies who turn to herbicides at the first sign of them.
If you are looking to purchase native plants, don’t be fooled by some of the signs at nurseries. Native plants are neither hybridized versions of the the original genus, nor are they plants originally from Asia or countries that share similar growing agricultural zones as ours.
In addition, even plants that may be native to other distant parts of the country we live in, may not be a food source to local prey animals, insects and larvae. A flower that is native to Western United States or Canada, may not provide the necessary traits that local fauna in our garden require.
Why do we need this third-tier predator prey relationship? Without these often overlooked prey species, there is no future for medium-sized predators like our song birds that depend on many of these third-tier predators and prey for protein, especially when rearing their young.
Here are constructive steps courtesy of the National Wildlife Federation that we can take to attract these third-tier predators into our gardens.
• Consider growing as many herbs and wildflowers native to your region. Look for plants that are ideally suited to beneficial insects. These plants often include daisy-like flowers including asters, black-eyed Susans and coneflowers as well as tickseed, goldenrod varieties, sunflowers and milkweeds.
• Work these flowers favoured by predators into your existing planting beds, or mass them into islands throughout the yard to focus both predator and prey to specific areas of the garden.
• Look for native plants that flower at different times. Spring ephemerals will get the woodland going early and provide potential food sources for birds migrating back into your area, while asters and other fall blooming natives will keep the predator-prey relationship going late into fall. This is especially important for birds migrating back to their wintering grounds.
• Combine predator-friendly plants of various heights to create a structurally diverse habitat.
• Don’t remove the fallen leaves from your planting beds. A healthy layer of leaf litter provides habitat for beetles, spiders and other important predators.
• Refrain from killing any insect or larva. You might be surprised what many quite scary-looking larvae become. Consider doing some on-line research into beneficial insects and larvae. Cornell University’s Biological Control: A Guide to Natural Enemies in North America is an excellent resource.
Middle-tier predators: Songbirds, chipmunks and toads…
Finally, let’s take a quick look at the middle-tier predators.
Many in this group may come as a surprise to gardeners who think of them as more prey than predators. Songbirds are probably the most recognizable of these animals we prefer not to recognize as predators. But don’t tell that to the millions of caterpillars, insects and spiders, that make up most of their diet during spring, summer and fall.
Well known entomologist Douglas Tallamy, in his book Bringing Nature Home, How You Can Sustain Wildlife with Native Plants, outlines the importance of these prey animals in his New York Times best seller.
“I cannot overemphasize how important insect herbivores are to the health of all terrestrial ecosystems. Worldwide, 37 per cent of animal species are herbivorous insects. These species are collectively very good at converting plant tissue to all types of insect tissue, and as a consequence they also excel at providing food – in the form of themselves – for other species. In fact, a large percentage of the world’s fauna depends entirely on insects to access the energy stored in plants. Birds are a particularly good example of such organisms,” he writes adding that 96 per cent of birds depend on insects to survive.
Just as an example, Tallamy’s research states that Chickadee parents need to find, depending on the number of chicks they are raising, as many as 570 caterpillars every day to sustain their family. If it takes 16 to 18 days before the babies fledge, that daily figure jumps to between 6,000 and 9,000 caterpillars to bring a clutch of chickadees to maturity.
Providing this amount of food in or around our gardens is necessary to sustain our chickadee population. Multiply this a thousand fold to account for all of the bird species competing for the same food in spring, not to mention frogs, toads, skunks, possums and even tier-one predators like foxes who dine on insects to the count of up to 26 per cent of their diet.
Bats, too, depend on insects eating as many as 1,000 in a single night as well as moths and other flying insects.
It doesn’t take long to realize that our gardens need to produce hundreds of thousands of insects, caterpillars and larvae to sustain only the first and second tier of predators that we hope call our gardens home.
But providing predators with enough food to sustain them and their offspring is not enough. We need a high percentage of these prey animals to escape predation to evolve into adult stage to allow the process to start all over again.
We need a world filled with butterflies, moths, dragonflies, spiders, birds, frogs, hawks, owls, foxes and even coyotes.
If we hope to have success, we have to smart small, and there is no better place to begin than in our gardens.