The first time Dr. Ashley Kennedy saw the term “insect apocalypse” in print was in the New York Times in November 2018. “It was a report about a meta-analysis of 73 independent reports of insect declines all over the world,” she said. Kennedy pointed out that while this is good news for human leisure time, “it’s bad news for pretty much everything else because insects are so critical to the ecosystem.” One big reason why is because the insect population has a such a large role in keeping birds alive.
Kennedy runs the tick program for the Delaware Department of Natural Resources and Environmental Control and was a part of a webinar from the Wild Farm Alliance.
“More than one in three North American bird species are declining just as insect populations are also declining, which is alarming,” Kennedy said. She noted that 96% of North American terrestrial birds rear their young on insects.
To help maintain a better quality of bird habitat, Kennedy set out to find which insects are the most important to birds, especially during the breeding season, along with what insects bird parents are choosing to feed their young.
Insects are not all equal when it comes to their needs and their required habitats. According to Kennedy, most insects are host specialists. “This means they have a particular plant that they need to survive. They cannot eat just anything. Most insects are herbivorous and 90% of them are insect herbivores,” she said.
Figuring out which insects are most important to birds, and therefore which host plants are supporting the most insects, was something Kennedy wanted to investigate. She launched a project called “What Do Birds Eat?” This involved crowdsourcing images of birds with arthropods in their bills from all over the U.S., Mexico and Canada. The result after three years was 7,000 submissions of over 300 North American bird species.
“A snapshot of what I learned is that Lepidoptera, which are insects that include moths and butterflies, are the largest arthropod prey group for most of the families of birds,” Kennedy said. “So, for 15 of 20 bird families, Lepidoptera was the number one prey source during the breeding season and 36% of all recorded bird-arthropod interactions involved Lepidopteran prey.”
For insectivorous chickadees and titmice, Lepidopterans made up more than three-quarters of their diet during the breeding season.
There are many reasons caterpillars make an ideal food for birds. They’re rich in carotenoids, which Kennedy explained are responsible for the brilliant reds, yellows and oranges that many birds have in their plumage. “That can be really important in helping them to signal their health and their potential as a mate because the colors indicate they are healthier than their duller counterpart of the same species,” Kennedy said.
Dan Gilgert, who worked for the NRCS for over 30 years and as well as Point Blue Conservation Science, joined the conversation to speak on the topic what birds need to help them continue to engage in a variety of life-maintaining activities.
Like human beings and other animals, birds need cover for perching, foraging, roosting, breeding, nesting, rearing, thermal loafing and escape. “There are different kinds of hiding that are necessary for birds to be able to nest and camouflage and to help keep predators from destroying or eating their eggs or their young,” Gilgert said.
He suggested farmers leave some of their crop standing. Crop stubble is really important. It can help provide food, nesting cover and escape cover when needed. Another benefit is it creates a thermal covering for birds during intense weather periods of heat, dryness or cold.
Different species of trees offer different types of cover for many types of birds. “No single plant can provide everything a single species will need,” he said, adding, “If you look around your ranch or farm, you will see the myriad ways that you are providing a form of habitat to them.” Gilgert used the example of birds eating insects in the eaves around your home or barn, saving you time by doing the clean-up job for you.
He also discussed various forms of water resources. It’s vital to make sure they are always available. Birds and bats can be aerial drinkers, so an open water source would be very beneficial in that situation.
Although Gilgert mentioned leaky pipes as a way birds can get water, he did so with caution. Along with open-top pipes that are used with fences, if the opening at the top is too wide, it “can injure or kill the birds because they will go inside the pipes and be unable to turn around and come back out. They might mistake it for a cavity for nesting, so cover the pipes that don’t have small apertures,” Gilgert said.
by Jessica Bern