It’s spring, my favorite time of the year. My trees are leafing out, and my perennial herbaceous plants are emerging from the ground. Soon, I’ll see more insects among them and more migratory birds, who will enjoy a springtime feast.
The timing of spring migration of many bird species in the United States and Canada is closely correlated with the greening up of plants and increasing abundance of insects. Birds depend on them for replenishing their energy as they migrate and, in the case of females, for providing protein needed for reproduction when they arrive on their boreal breeding grounds. By preying on these insects, they also keep populations in check, providing a natural service to us as we spend more time outdoors in the spring and summer. While discussions of insects usually conjures up images of sallying flycatchers, swifts and nighthawks, many other species we don’t normally think of as insect-eaters, like hummingbirds and sparrows, also rely on insects during migration and breeding.
Recent science revealed that over my lifetime, the US and Canada have lost more than 30 percent of aerial insectivores from our grasslands, wetlands, and forests. Insect populations are also decreasing because of loss of habitat and increased application of pesticides in our agriculture areas and our homes and communities. Additionally, climate change has resulted in insect abundances peaking earlier in the spring, meaning that when our feathered friends are migrating, they’ve arrived too late to the buffet. This results in birds migrating more slowly, which then jeopardizes their chances of securing a high-quality breeding territory or even successfully completing migration at all. As a consequence, many migratory bird species are at risk of further decline.
I recently sat down for dinner with a long-time friend and research colleague, Mike Ward, who along with his students and collaborators at the University of Illinois Urbana-Champaign, are studying the effects of reduced insect abundance on Eastern Whip-poor-wills and Chuck-will’s-widows in the Midwest and land management techniques that protect both the insects and the birds. Whips, as they are generally referred to, are near threatened based on the IUCN and are highly vulnerable to climate change, revealed by Audubon’s 2018 Survival By Degrees report.
Eastern Whip-poor-wills are early migrants, returning from their winter grounds in Mexico and Central America as early as February.
In many places, Ward and his research team are seeing whips disappear over the course of several years and at the same time fewer and fewer insects, like moths, that they depend on. Pesticides and reductions in habitat appear to be driving the declines. Although, by working with landowners and agricultural producers, we can increase habitat by reducing invasive plant species. This improves habitat for the moths and butterflies that whips rely on. By reducing pesticides in our neighborhoods, we protect insects and the plants they depend on, and also reduce the harm they cause to our health.
While many people think of nighthawks, like whips, and flycatchers when talking about insectivorous migratory species, many other species, like the Rufous Hummingbird, depend on insects for food as well. Rufous Hummingbirds make incredible migratory journeys each spring as they migrate northward from Mexico to breeding grounds that stretch from California to Alaska, further north than any other species of migratory hummingbird. To survive migration and increase their chances of successfully rearing young, they broaden their diet to include insects in addition to nectar. Insects provide hummingbirds with the protein they need to reproduce and that their young need to thrive. Native plants attract small insects that offer an abundant source of protein. Like Eastern Whip-poor-wills, Rufous Hummingbirds are classified as near threatened and are highly vulnerable to climate change.
Growing native plants in backyards, parks, and community areas increases the availability of food for birds, because they are known to host more insects than non-natives plants. Many native plants species also do well on balconies for those living in urban areas, and they can provide small snacks for migratory birds as they pass through these areas during migration. Check out Audubon’s Plants for Birds database to learn about which plants are native to your area and which types of birds depend on them.
As spring advances and our neighborhoods take on new colors, keep an eye out for birds having an insect snack and appreciate the value they provide by keeping insect populations in check.
