Doug Tallamy: A world without insects is a world without biodiversity

Carolina chickadee

Published Nov 12, 2017
​Biodiversity starts with insects.
Doug Tallamy delivered an absolutely riveting presentation last week at the RBG. A Chickadee's Guide to Gardening took the perspective of a (Carolina) chickadee's experience in a regular garden as a place to breed: would there be enough food and shelter for it to live its life, including rear its young?

Doug told us how he had surveyed over 1176 trees in Portland, Oregon. He noted that of this number, only 100 were indigenous. He observed that there were not that many birds: “Woodpeckers, kinglets, junco etc aren’t breeding in our greenest city, because there are no trees to breed in.The city is a biological desert!”
Most of our cities lack biodiversity, but, as Doug says, we can fix this. He demonstrated how to do so from the perspective of birds, and more specifically, through a year of the life of our little Carolina Chickadee friend.

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In the Spring

Goldenrod Hooded Owlet MOTH

Chickadees are cavity nesters (as are 85% species of north American birds) so it is important to leave snags in your yard. For nest-building purposes, a good tree is the Winter Pine. Chickadees like to use hair (horse and cat hair) to line their nests.
Time to feed the young baby chickadees! Did you know that baby bird can’t eat seeds? Birds rear their young on caterpillars. They eat seeds and berries after they reproduce.
“Birds absolutely need caterpillars, lots and lots of caterpillars to make a clutch of chickadees,” Doug pointed out. Doug told the audience that he watched chickadee parents bring in about 30 caterpillars in 27 minutes.
“There were 17 species of caterpillars in 3 hours,” Doug said. That means 6000-9000 caterpillars to make a clutch of caterpillars.
So why does biodiversity of caterpillars matter, Doug asked the audience?
“If I had 1-2 species a year, that wouldn’t be enough to reproduce, so there must be diversity and stability in this ecosystem,” he said.

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Bur Oak Tree

How do we make landscapes that produce abundance?

​We have to consider the specialized relation between birds and insects. So we have to build landscapes of food webs for caterpillars. We need trees like black cherry, black walnut, native maples, and of course oaks, which are the kings of trees that support biodiversity.

Also, why focus only on backyard habitat, “why hide it in the back? That means you are cutting the diversity in half.”
"What we need to remember is as individuals, we own a lot of property (ex. 85 % of Texas is privately owned), which means we can do a lot: “We would be almost there.”
Habitats HAVE TO SUPPORT life. They also offer invaluable serves like sequestering carbon (soils can sequester 7 times the amount of carbon in the air), cleaning and managing water (watershed plants protect our watershed), enriching soils, and supporting pollinators.

Doug offered us a challenge: the 12 by 12 experiment. He suggested we fill a space this size with native plant species, be it trees, bushes, or flowers. Doug himself planted a white oak from a seed, which has grown 25 ft in 14 years. He notes that on July 25 2014, the counted 410 caterpillars and 19 different species.
We need to understand that it takes tens of thousands of years to develop those relationships. That's why it is crucial that we plant native species of trees, and a wide range of biodiverse ones at that.

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Rosa multiflora

Compare native species to non natives: Oaks host 557 caterpillars Ginkgo (Not invasive but does not support life) hosts 4 species of caterpillars. Native primus hosts 456 caterpillars, Zelkova supports no caterpillars. You get the picture.
What we are seeing now, is a biological invasion or non native species like the calary pear, which is on the move, and spreading. This is “ecological castration,” a “biological pollution,” says Doug.
Doug gave an example of the Sunset Beach, establishment and said, “They may have the right to pollute on their lands, but not on others.”
Basically, it is awful to think that "we are starving birds by the way we landscape."
Sterilized neighbourhoods (which are ecological traps) hurt migrating birds, so an important part of conservation is to pick that trees wisely. Doug suggests that we think of plants in our yards as if they were bird feeders.
When choosing plants that have berries, remember that birds and berries have a co-evolved relationship. While Myrica and Viburnum  have 50.3% fat content, Rosa multiflora has 0.9% fat, (has high sugar, not fat). Buckthorn berries make birds throw up.
Find out what sorts of habitats are needed for the Hamilton area and the best natives and diversity on Paul O'Hara's great list. O'Hara is a field botanist, landscape designer and native plant gardening expert with Blue Oak Native Landscapes. Find more resources here: Native Plant Finder and Conservation Halton.

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Fall and Winter Garden

Do not dead head flowers (joe-pye weed, evening primrose, blackeyed susan): "We have to leave the seeds on the plants!" Doug says. Chickadees hide their seeds in nooks and crannies in the fall, and find them later. They grow their brains in the fall by a third of its size. So leave these crags if they are going to make it in your backyard. (Blue Jays don’t cache. They store them individually even in disturbed soils. They hide around 4,500 acorns each fall and remember where 1 in 4 are, lol!).
50% of a chickadees diet is insects. So we need to be making caterpillars. Goldenrod hosts insects in it, so don’t cut your rods.
Responsibility Lies With YOU!
The idea that "humans are here and nature is somewhere else," has to go. We must maintain the co-evolved relationships before they disappear. Doug believes that in the near future, it will be against the law to destroy habitat. The responsibility for our lands lies with us. Yes, we do have to teach our kids but we can not wait for another generation, we have to do it NOW.
Thank Doug for a great presentation! Check out Doug's book Bringing Nature Home for more ideas on how to create a paradise of biodiversity in your front (grin) yard.

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