Resolved, to grow more insects

Swallows, Purple Martins, Chimney Swifts – these are the birds that soar high above us on a summer day, their song connecting us to a world we can never know above our familiar places.

They share our human habitat, but they don’t eat our food, so we don’t consider them to be pests, and they in fact provide what the market calls environmental services by consuming insects that might bother us or eat our crops.

But they’re in trouble. As Mike Cadman, a songbird biologist with the Canadian Wildlife Service, told a recent meeting of the Midland Penetanguishene Field Naturalists Club, birds that catch insects on the wing have experienced dramatic declines in the past few decades.

What was happening didn’t become clear until research for the second version of the Atlas of the Breeding Birds of Ontario was completed. Cadman co-edited both the 1987 and 2007 editions. As the data came in, researchers noticed that the worst-hit birds are insectivores, members of the Swallow, Nightjar or Flycatcher families. Those declines were corroborated by another large project, the Breeding Bird Survey.

According to the Breeding Bird Survey, the Chimney Swift declined the most since 1970 in Ontario with a drop of 97 per cent.

The Barn Swallow, the most widespread songbird on the planet, has experienced a decline of 69 per cent in Ontario.

The Purple Martin was also hard hit, its population reduced by 94 per cent – although the Atlas showed that it is still widely distributed in the immediate vicinity of the southern Great Lakes shorelines. That is one of many observations of which researchers take note but the causes are not well understood. Among the others:

-For Chimney Swifts, at least, there was a significant diet change during the DDT era, when the birds which had been eating mostly beetles, switched over to true bugs. This was discovered through examination of a 7-foot pile of guano in the bottom of a chimney in Kingston that had been frequented by swifts for decades. It points to a change in the insect fauna due to pesticides and strengthens the arguments that they may be involved in the aerial insectivore decline.

-There has been a decline in the weight of adults of 13 species of aerial insectivores returning to the Long Point Bird Observatory in spring, suggesting problems south of here in the wintering grounds or during migration.

- “Hawkers” (birds that hunt their prey on the wing) are doing worse than “sallyers” (birds that perch and watch, before dashing out to capture a meal).

- The birds that migrate the longest distances and winter in South America – such as the Chimney Swift, Barn Swallow, Common Nighthawk – are also doing less well.

One explanation is obvious: there used to be a lot more insect life above and around us, just as we used to have a lot more insect death plastered against our windshields on a summer day’s drive. Although those of us who can recall conditions in the ‘70s have experienced this decline in our lifetime, Cadman said there’s been no research to quantify it.

And there are many other factors that could be contributing to the decline of these graceful and agreeable birds.

-  Climate change, creating more extreme weather – including hurricanes - that’s tough for the birds to survive.

-   Global warming, which causes insect and caterpillars to reach maximum populations earlier in the spring, pushing the insect peak out of synch with the nesting timetable. It is when they are feeding their young that the birds have the most need of plentiful insect food.

-  A decline in Ontario in the area of farmland, and a change in the type of farming, towards more crops, with heavier use of pesticides, and away from livestock on pasture and grasslands, which produce plentiful insect populations.

-  Pesticides, of course; the newer class of chemicals like neo-nicotinoids are a problem because they enter the structure of the plant and in turn contaminate the insect that stops to pick up pollen, sample nectar or chew on a leaf. They are very effective in killing insects and may be contributing to the low number of insects available. Seeds treated with neo-nicotinoids may be lethal to seed-eating birds, but there’s no research to look at whether birds pick up the chemical from contaminated insects.

-  Loss of habitat – loss of the old barns and bridges with their multiple nesting spaces; capping of chimneys and all the other construction methods that exclude birds; changes to rivers that lead to artificial stabilization and the loss of natural embankments (this has prompted bank swallows to move to gravel pits, but there, they can lose their nests to as excavation inexorably proceeds).

What to do? Clearly there are matters that need to be addressed politically, and we should all press for that to happen. But each of us can also make a difference in our own spaces.

Remember, during the breeding season, ALL birds, even seed-eating birds, consume insects and their larvae (or caterpillars); this is the high-protein diet nestlings require, and parents forage incessantly to find sufficient quantities.

So as gardeners, we should help out our struggling avian friends and aim to grow our outdoors insect populations. Overcome your culturally induced distaste, get a magnifying glass so you can discover how amazingly intricate and beautiful even a humble shield bug can be.

Last year, I spent a lot of time looking for bees and other insects. There were some plants that could be relied on to play Party Central, usually the ones with clusters of many small flowers:

- Milkweed was always surrounded by a hovering horde of bees, wasps and flies of every description, and was one of the few where I would reliably find honey bees. It is of course the host for the Monarch butterfly we love but see fewer of every year, so it’s essential to have it. There are several varieties, among the best for gardens are the brilliant orange Butterflyweed (Ascelepias tuberosa) and the pink bi-colour Rose (or Swamp) Milkweed (A. incarnata).

- Goldenrods (Solidago) were also popular. They are not a source of allergies, the unattractive ragweed is the culprit there, but the wild ones do like to take over. For gardens, try the Fireworks Goldenrod cultivar, which stays where it is planted.

I found countless small creatures buzzing around the heads of annual Sunflowers (Helianthus annuus), navigating the spiral pattern created by the hundreds of small flowers that turn into seeds.  (The spirals, by the way, provide the most efficient way of packing as many seeds as possible into the flowerhead).

Beebalm, particularly the showy red variety known as Oswego Tea (Monarda didyma), attracted bees, butterflies and – bonus - hummingbirds. Other insect magnets were Obedient Plant (Physostegia virginiana), Anise Hyssop (Agastache foeniculum), Rattlesnake Master (Eryngium yuccifolium) and Black Snakeroot (Actaea or Cimicifuga racemosa). Asters (Symphyotrichum) of every variety reigned supreme as the season drew to a close. 

There were a number of non-natives that proved insect-friendly. Perennials of note include Globe Thistle (Echinops ritro), Knautia macedonica and Sedum. In the weed department, leave room for some Queen Anne’s Lace (Daucus carota, aka wild carrot). 

What to do if the creatures you have kindly invited into your space show signs of abusing your hospitality by defoliating your plants? Don’t panic; a jet of water is often enough to wash off unwanted visitors and the odd bite or wilted leaf is no big deal. With luck, a bird may show up to help out.

The good news is that native plants are more resistant to pests and give you a better chance of achieving a natural balance of the predator-prey relationships in your garden.