A large and avid audience gathered at the library on Jan. 24 to hear Tim Purtell’s Friday Night Dialogue on creating a haven for birds and bees in your own garden. Most people find the visits from colorful wildlife a treat, but Mr. Purtell set the discussion in the context of alarming drops in these populations.
Recent research, he told his audience, shows bird populations have plummeted in the past five decades, dropping by nearly three billion across North America — an overall decline of 29 % from 1970. More than 1 in 4 birds have disappeared from the landscape in a mere half a century. Habitat loss is likely an important driver in some areas. Other causes may include pesticide use, insect declines and climate change.
Insects are also in trouble. A 2017 German study he quoted showed that flying insects have declined 75% over a 29-year period. The report says this yet unrecognized loss of insect biomass must be taken into account in evaluating declines in many species that depend on insects as a food source.
Yet the news is not all gloomy, he told the audience.
Waterfowl as a group saw a population increase of 34 million individuals since 1970, thanks largely to wetland conservation efforts. Raptors, such as the bald eagle, also fared better with a gain of 15 million birds thanks largely to a ban on DDT in 1972.
These numbers show that taking steps like wildlife management and habitat restoration can be effective to save species in steep decline.
Mr. Purtell drew on his own experience in encouraging the audience to design gardens to provide havens and food for birds and insects. While he showed pictures of nature preserves in Florida and Maine as well as Mashomack and First Causeway, he said mini versions of such preserves surround his house, providing a small oasis. His house has a garden instead of a lawn; alternatively some people could set aside a part of their lawn to plant natives, to attract bees, butterflies and wasps to the nectar and pollen from February to October.
He pointed out that native oak, growing on Shelter Island, is host to more than 600 types of larva for butterflies and moths, providing more food than crepe myrtle. Long Island native bayberry is deer-resistant and drought tolerant, and does well, he said, in his yard’s sandy soil. He also grows beach plums: “the plums mostly feed the chipmunks,” he said.
He listed some other plants that will not only thrive in your garden, but attract the winged creatures who’ve been at risk. Mountain mint (Pycnanthemum tenuifolium) is a flowering plant that blooms for the month of July and attracts many insects.
Butterfly weed (Asclepias tuberosa) — not the butterfly bush — blooms with bright orange flowers. These are essential for the stunning monarch butterfly. These have been devastated, primarily by the use of Roundup in the midwest, he said, which “wiped out the milkweed.”
The more milkweed you have in your garden, Mr. Purtell explained, the more the butterflies’ chances of success, so if you grow it, they will come.
To attract hummingbirds, he has two colorful trumpet vines. In August, summer sweet (Clethra alnifolia) or sweetpepperbush is attractive to bumblebees. Vibernum dentatum (arrowwood) blooms in June and July and produces blue berries that catbirds love.
“You also need a mix of layers,” he said. “The tree canopy, the shrub layer and the lower level. Some birds flock to certain layers.”
Contrary to what some people think, it is not necessarily easier to keep this type of garden than a traditional lawn. “You can just mow the lawn down,” he said, but he found, at least at first this native garden required a lot of weeding. “I started with small containers, which left a lot of space for weeds. If I had it to do again, I would plant bigger areas.” He has a lot of blue stem grass that he’s interplanted among the flowers; it helps to suppress weeds.
Mr. Purtell described his garden as a “living thing,” which has changed over the past 20 years and will keep changing. In the fall, he said, he does no cleanup, leaving all the plants with their seeds for the birds to eat. “I leave as many leaves as I can; leaf mulch is ecologically really rich.”
For Islanders who were unable to attend Mr. Purtell’s talk last Friday, he will reprise the presentation this summer at the Havens Barn at the History Center on a date to be announced. In the interim, he will be collecting stories from local gardeners who have introduced plants to attract flying friends, and adding them to his presentation.