The Decline in Pollinator Populations and Steps Homeowners Can Take to Save These Essential Birds and Insects.
Professor of Entomology and Wildlife Ecology and Author of Bringing Nature Home Talks About the
- Bees and monarch populations are seeing precipitous declines. Why do you think this is happening?
It’s happening because we’ve taken away what they eat. This is not rocket science. Monarchs are an index of all the other insects that are disappearing. As a caterpillar, they’re a host plant specialist and their food is milkweed. As we eliminate weeds in our farmland and in our roadsides, they find very little to feed on, so their populations are small. On the Monarch’s return to Mexico, they need flowering plants and nectar, and they’re finding brown fields. That’s why they’re disappearing, along with our 4000 species of native bees and countless other insects that nobody is following.
You will hear that it is because we had a drought, a cold spring or problems in Mexico where monarchs overwinter. But the real cause of the monarch’s decline is the loss of their only host plant, milkweeds. Every year there have been half as many Monarchs as the previous year. As of last winter, we have 3.6% of the population we had in the 70s. Weather fluctuations are not new. It is the tiny population of what they used to be that is new.
That’s why the small habitat patches that do remain are not enough to sustain the populations of insects and other types of biodiversity. That’s one of the problems with the Endangered Species Act. We don’t do anything to help declining species until their populations are dangerously small.
- Why are insects, not just pollinators critical to maintaining the diversity of other species?
E.O. Wilson wrote an article in 1987 entitled, “The Little Things That Run The World.” Insects actually sustain life on land. Insects are the basis of food webs and transfer energy to all other animals. If you eliminate insects you eliminate other species. If you eliminate pollinators you eliminate 90% of our flowering plants. Insects pollinate 80-90% of our plants. Plants make oxygen; they regulate our watersheds; they preserve our topsoil. If you take away plants, you take away the eco-system services that humans depend on. We’re creating a world that is not conducive to life.
- What are some simple steps homeowners can take to support insects and pollinators, and encourage wildlife and biodiversity?
It’s actually quite simple—abandon the age-old concept that humans live here and nature is somewhere else and embrace the concept that we need to share our spaces with nature. We enjoy a walk in the woods; we enjoy seeing butterflies, birds, beautiful flowers, etc. Research has shown that spending time in nature is the very best way to recharge your attention span and deal with the stresses of life. Living with nature is a healthy necessity, not a sacrifice we must endure.
We have 45.6 million acres of lawns and it is growing by 500 square miles each year. That’s an area 8 times the size of New Jersey from which the species that run our ecosystems have been removed. Now that we see the big picture, homeowners can take action.
Lawn should be restricted to the areas on which we walk in our landscapes; it is a mechanism for guiding us through our landscapes. Lawn should not be our default landscaping practice. If we cut the area of lawn in half and we could create the equivalent of a new national park that is 20 million acres in size. That alone would create the biggest natural area in the nation, bigger than most of our national parks combined.
- For those of us with established landscapes, how would you suggest we begin to transform our yards?
Put the plants back! People can add productive native plants that support wildlife back into their yards. In most areas of the U.S. you can plant oaks. Oaks support at least 557 species of caterpillars (think bird food). Most native trees do this, but oaks do it better. Their root system is massive. Oaks, cherries, willows, birches and poplars are great choices. Asian ornamental species don’t do this at all. Every time a homeowner plants a plant from Asia, they have to realize it won’t support the insects that support our birds and viable food webs.
- What advice would you give to new homeowners about landscaping?
Make a plan. Most people just hire someone, so hire someone with the skills of an ecological landscaper.
If you get involved yourself, make it a hobby that you can enjoy for years. Pick at it, don’t feel you have to do it all at once. You can simply put trees in your yard and then build beds around those.
Choose your plants wisely and plant young specimens. Most of the plants in our yard at home started from seeds or very young plants. You get a healthier tree or plant when you start small, because it isn’t root bound or root pruned. People say, ‘but I won’t be there to enjoy them’ about young trees, but in 14 years, our oaks have grown to 30 feet tall and were started from acorns.
- What are your go-to native plants?
Everywhere they can (or should) grow, oaks would be number one. Native viburnums, solidago (goldenrod), sunflowers and asters are very high on the list. Native monarda (bee balm) is a great choice. (For more info see the Bringing Nature Home Best Bets: What to Plant lists. If you live west of the Mississippi, you can consult Utah State University's Gardening for Native Bees Fact Sheet. You want your landscape to support the food web, including insects that are part of the food web and insects that are important pollinators. In the East, button bush, American plum, Clethra, Joe Pye weed, Virginia sweetspire, and native hollies are super pollinator plants. In the west, I recommend planting cottonwood trees and some of the many species of Ceonothus.
You can target certain species you may want in your yard. I wanted to have Zebra Swallowtails in my yard. They feed on pawpaw, so I planted several pawpaw trees. It took nine years, but the swallowtails finally found our pawpaws. Now we have a healthy population of the butterfly, and we get to eat paw paws.
If you put a bush or tree in your yard in the appropriate place, you can see a difference, in everything from insects that use that plant, to the birds that eat those insects. You’ll get positive feedback and further motivation. There’s no better way to expose kids to nature than to put it right where you live.
Try to build a balanced landscape that’s doing more than one thing. I have found that most people don’t get motivated to do this until they get a dose of reality, of how quickly the species we depend on are disappearing. Plants are not just for decoration, plants are vital ecological entities that do so many things.
Doug Tallamy is a professor of Entomology and Wildlife Ecology at the University of Delaware and author of Bringing Nature Home and The Living Landscape with Rick Darke (published by Timber Press Press June 2014).
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