This past month, Oct. 12 to be exact, was World Migratory Bird Day. Although it will be well past peak migration by the time you read this, there surely will still be some stragglers and maybe even some murmuration along the Connecticut River. Established in 2006 by the Smithsonian Institution, this day was developed to bring attention to the fact that many migratory bird populations were declining at an alarming rate.
As with so many other aspects of our world, this decline is due in large part to human activity. Many theories exist about light pollution and warming temperatures, but the emphasis this year by the Smithsonian is the decline of available insect species, one of the most important food sources for birds. Vital for a great majority of birds at all times, insects are critical for migratory birds that binge eat before take-off and on which they depend along their routes.
Human activity has changed our ecosystems dramatically, not just because of buildings and paved roads, but because of a movement away from native plants in favor of manicured lawns and ornamental plantings. Insects are host-specific and usually feed on just one or a few plant species as they have evolved over a long period of time. Luckily, there has been a recent push to do away with non-native ornamentals and allow or plant native species to grow. Unfortunately, this effort is not keeping up with the decline in bird populations and we need to do a better job.
Despite the colorful butterflies we see during the day, it is a fact that most insects are active at night, and are unfortunately attracted to our artificial lights, where there is usually no food. This unsuccessful flight can lead to exhaustion and death. We can counteract this by using yellow LED lights. For some reason, insects are not attracted nearly as much to them, saving them from needlessly expending energy.
Homeowners with trees are conditioned to rake up all those leaves that come down in the fall and dispose of them. Leaf litter, however, is a valuable habitat for insects to overwinter, and in some cases, it is necessary for insects with complete metamorphosis to complete their life cycles. (Complete metamorphosis is the type with four stages: egg, larva [caterpillars], pupa [chrysalis and cocoon] and adult.) If a homeowner leaves a bit of the lawn area un-raked, it will help.
Hopefully it goes without saying that the use of herbicides and pesticides is totally detrimental to the health of insects and has its effects far up the food chain. Most of these chemicals will kill insects directly and they may change the chemistry of the host plants so that insects can’t eat them. If you plant native species, and maybe let a bit of your lawn area grow wild, you won’t need these chemicals.
Making some or all of these concessions can help to keep our world populated with the variety of birds we still have and maybe allow some dwindling species to make a come-back. It’s certainly worth a try.