Grim news: According to a 2019 study, bird populations in the U.S. and around the world have diminished by at least 30 percent since 1970.
Songbirds have been particularly hard hit. Insect populations are declining, too — by about 1 to 2 percent a year world-wide, according to the Xerces Society, but much faster for certain insect species or types.
The greatest threat to biodiversity in general is habitat loss, mostly through the spread of urbanization and conventional agriculture. Climate change makes things worse, as droughts, hurricanes and wildfires make things tougher for all life on the planet.
Insects, crucially important to functioning ecosystems, are assaulted directly with pesticides and indirectly with massive herbicide use, both domestic and agricultural, that degrades their habitat and kills the plants they feed on. Insecticides and herbicides affect birds, too, both directly by poisoning and indirectly by destroying food sources and habitat. How can gardeners help?
For a start, of course, we can swear off pesticides and herbicides. Each solitary gardener may feel powerless to make a difference, but remember how many of us there are. A recent national survey showed that only about 18 percent of gardening U.S. households grow organically, so there’s lots of room for improvement.
While a single, isolated nature-friendly garden may not help much, entire suburbs and rural developments, especially if they abut healthy natural areas, could potentially do a lot to expand and connect wildlife-friendly habitat. If your own yard borders on a natural or wild area, that’s all the more reason to garden organically.
Other than avoiding pesticides and using organic fertilizers, how can we make our gardens friendlier to wildlife? First, leave some areas undisturbed. Being messy is harder for some people than others, but a few patches of unmown grass can be designed to look deliberate, and even artistic-looking debris heaps and rock piles will provide safe harbor for snakes, beetles and all sorts of other arthropods, most of which are beneficial.
When you break down a neglected compost heap, take care not to injure little snakes nestled in the dry top layers. Garter snakes eat slugs and snails! Shrubs and trees provide vital food, shelter and nesting sites for birds.
When we moved to our present house just over 10 years ago, the average-sized lot was mostly covered in turf, with a few maturing fruit trees. Bit by bit, we smothered most of the turf and planted quite intensively with a variety of shrubs and big perennials, some native, some not. We’ve been amazed how quickly the bird population has grown in size and variety, in spite of many neighborhood cats. If we had more space I’d plant a big, untrimmed mixed hedge of native shrubs and small trees — an efficient way to provide food and habitat for a variety of birds and other critters.
Online you can easily find lists of plants for native pollinators and their larvae, and they can be useful if you are looking to accommodate specific species. You’ll attract a vast array of bees and other insects simply by ensuring you have lots of flowers in bloom for as much of the year as possible, but don’t forget it’s their larvae that munch on leaves, and they are pickier.
We can help gleaning birds and overwintering insects by postponing fall clean-up until early spring, or by cutting perennials back to 6-12 inches, rather than all the way to the ground. Avoid overusing heavy mulches of fir bark and wood chips — they interfere with ground-nesting bees and beetles. In summer, water is crucial too — not just to birds, but insects also. Shallow containers are safer than deep ones for a range of critters, especially if you add a few stones for insects to perch on. Some insects, butterflies and mason bees included, use mud-puddles. Overhead watering in dry spells provides droplets that insects and small birds appreciate.
Rachel Foster lives and gardens in Eugene. She can be reached at email@example.com.