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Native plants support the food web - OSPCA talk

Last week, I was the speaker at a fundraiser for the Midland branch of the Ontario Society for the Prevention of Cruelty to Animals (a good cause, and a fun event). My theme was 'Saving the World with Native Plants... and enjoying every minute!"

Saving the world might sound overstated. But if you familiarize yourself with the work of Doug Tallamy, chair of Entomology and Wildlife Ecology at the Unversity of Delaware, you will realize that we are moving into a biodiversity crisis. If we carry on, we will squeeze all the species that need wilderness to survive right off the planet. But he believes we, the world's gardeners, can turn things around. We can stitch together a patchwork of rural back yards, urban gardens and private spaces and turn them into wildlife refuges and corridors.

We can begin to rebuild wilderness right where we live.


It sounds like work. But as I told the OSPCA audience, gardening with native plants opens the window on a whole new level of fun. It seemed an appropriate crowd with whom to share my delight in the creatures who live in "my" space, though I consider it truly "their" space. I'm just the recent arrival, lucky enought to be a custodian for all these birds, butterflies, moths, spiders, bees, dragonflies, frogs, toads, snakes, chipmunks, squirrels, etcetera.

In my talk, I drew liberally from Tallamy's work, including from a DVD of one of his talks I purchased from Wild Ones, an organization that promotes natural landscaping. I was fortunate that local nature photographer Jennifer Howard allowed me to use some of her really great pictures of parent birds foraging and feeding their young.

I think there were three key messages that I tried to convey.

-First, the critical importance of maintaining a well-stocked larder of insects and their caterpillars. When feeding young, even birds that we think of as seed-eaters turn to caterpillars - because they're easily digested and high in protein. Ninety per cent of birds raise their young on insects and caterpillars.

Tallamy studied a pair of Carolina Chickadees in his yard. He found:
• A pair can deliver food once every three minutes.
• They forage from 6 am to 8 pm.
• One pair delivered 30 caterpillars in 27 minutes.
• He figured they delivered 390-570 a day.
• The chicks spent 16-18 days in the nest
• Just getting the young to point where they can leave the next takes 6,240-9,120 caterpillars

And a chickadee is a small bird. Larger ones need more. Something to remember when we landscape for birds – it's not just about seeds and berries. 

-Second, native plants support way more insect life. This is because plants don't like to be eaten, and arm themselves with distasteful, even toxic chemicals to deter insects. But insects have evolved over millennia to develop digestive systems that allow them to overcome the defences of specific plants (for instance, the Monarch butterfly and milkweed). "Ninety per cent of insects that eat plants can develop and reproduce only on the plants with which they share an evolutionary history," Tallamy says in the DVD talk.

While native plants can support hundreds of species of insects, plants introduced from elsewhere (which make up an overwhelming percentage of the ones we use, the ones on sale at garden centres, from pansies to petunias to peonies) support zero to a few.

You might think you don't want all those insects - but a diversity includes beneficials, like pollinators that play an essential role in life, and predators, that keep the pests in check. If you spray to kill off the "pest" caterpillar, the predators that have the job of keeping the pest species in check wil starve or vacate the premises.

Even among native plants, not all are created equal supporters of biodiversity. The following tables based on Tallamy's research can be used as a guide when deciding what are the best choices in terms of supporting your garden food web.

Productive native woody plants by number of butterfly/moth species supported
• Oak 534
• Black cherry 456
• Willow 455
• Birch 413
• Poplar 368
• Crabapple 311
• Blueberry 288
• Maple 285
• Elm 213
• Pine 203
• Hickory 200
• Hawthorn 159
• Spruce 156
• Alder 156
• Basswood 150
• Ash 150
• Rose 139
• Filbert 131
• Walnut 130
• Beech 126
• Chestnut 125

Productive native herbaceous plants by number of butterfly/moth species supported
• Goldenrod 115
• Asters 112
• Sunflower 73
• Joe pye 42
• Sedges 36
• Honeysuckle 36
• Lupine 33
• Violets 29
• Hardy Geraniums 23
• Black-eyed susan 17
• Iris 17
• Evening primrose 16
• Milkweed 12
• Verbena 11
• Beardtongue 8
• Phlox 8
• Bee balm 7
• Veronica 6
• Little bluestem 6
• Cardinal flower 4

-Third, people need to understand the difference for butterflies between a host plant and a nectar plant:

Host plant
• Source of food for larvae (caterpillars)
• The caterpillar has adapted to develop mechanisms that allow it to overcome the plant's chemical defences
• Butterflies are picky about where they lay eggs – there has to be enough of the host plant to support a large number of caterpillars. Just one milkweed won't entice a Monarch

Nectar plant
• Source of food for adult butterflies– nectar
• Flowers with multiple florets are better than large single flowers
• A succession of flowers is needed, with the ones in late summer the most important

My final message: Plants are like pets -- they should not be an impulse buy
• Research where plants originate and what their habits are
• Ask the nursery where they were propagated (the answer you want to hear is Ontario but, alas, most are trucked from the west coast)
• Ask if they have been sprayed with neo-nicotinoids 
• Ask if they have been sprayed with any pesticides
• A "new introduction" – may be fashionable but not necessarily desirable
• Don't buy plants you don't know anything about
• Get 'Grow Me Instead' pamphlet

Note: Return of the Native opens this Friday at 1 pm. I will be open Fridays and Saturdays, 1-5 pm, from now until August, then open again in September. Location map (Google Maps has put me a little to the east on Flos Road 10 East, I'm just 1 km east of County Rd. 27 north of Elmvale). 


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