Insecticides, Blue Jays, eggshells
Answers to readers' questions about pesticides and hummingbirds, paint-eating jays, and offering eggshells
Published: April 20, 2012
If I treat honeysuckle vines with a systemic insecticide to get rid of aphids, will it harm the hummingbirds that feed on the flowers? — Pat Crandall, Inchelium, Washington
Systemic insecticides are present in all parts of plants that were treated with them, including the pollen and nectar. One of the most common systemic insecticides on the market today has been found to pose significant risk to bees, indicating it may be a threat to other pollinators as well.
Aphids have multiple generations each growing season. Some people apply insecticides frequently in an attempt to control them, but the effort is not particularly effective, nor is it necessary. Aphids rarely kill honeysuckle vines, although they can be unsightly. The best way to control them in your garden is to hose them off plants with a hard stream of water. Or you can put a few drops of dish soap in a spray bottle of water and apply directly to the aphids.
I cannot emphasize enough that people who care about environmental health should not use pesticides or lawn chemicals. In the United States, pesticides are allowed to be sold based on risk-benefit analyses of their active ingredients. This does not mean they are non-toxic; pesticides by definition are poison. Further, the products include additional ingredients, and consumers often use them in combination with other lawn-care or pest-control formulations. We know little about how this toxic soup affects environmental and human health.
When you plant a diversity of native species and eliminate chemicals, you create habitat that is used by a wide range of beneficial organisms. You’ll have fewer pests and attract more birds, and all will be much healthier for it.
How do I keep Blue Jays away from my home? They are taking the paint off the house. — Dave Vale, via the BirdWatchingDaily.com forum
The Blue Jays are eating the paint for its calcium, in the form of calcium carbonate, which is used in many paint formulas as a pigment extender. Birds often seek out supplemental calcium during the breeding season to help with eggshell formation and to feed chicks while their bones are developing.
Songbirds can’t store calcium in their bodies, so they obtain it from the environment, often from snail shells, grit, or arthropods whose exoskeletons contain calcium.
For reasons not completely understood, Blue Jays seem to require a lot of calcium all year. They eat paint off houses to satisfy their demand.
Jays are especially likely to eat house paint in areas that experience acid rain. The rain reduces calcium in soil, so it is not available in sufficient amounts to arthropods or snails, the birds’ natural sources of calcium.
When a lack of soil calcium causes prey numbers to fall, the birds look elsewhere.
You can deter the jays from eating paint by offering eggshells. I explain how in the answer below.
How do I provide eggshells to birds? — Leah Hladkyj, Toronto, Ontario
Eggshells can be an excellent source of calcium for birds. This is especially important for female birds in the nesting season, but as I explained above, some birds need higher amounts of calcium year-round.
Because eggshells from your kitchen can be contaminated with salmonella bacteria, they need to be sterilized before you put them out for birds.
Here are two ways to sterilize eggshells:
• Place them in boiling water for 10 minutes.
• Or rinse them, place them on a baking sheet, and heat them in an oven for 20 minutes at 250°F. Don’t let them brown.
I don’t recommend sterilizing eggshells in a microwave.
After boiling or heating, let the shells cool and dry, crush them into thumbnail-size pieces or smaller, and place them outside in shallow bowls, a raised platform feeder, or on open ground, where they are visible to birds.
You can prepare eggshells ahead of time, and store them in a bag or container for later use.