Twenty-five years ago, Cathy DiSalvo attended a talk that profoundly impacted her life — and her garden.

The speaker was Nancy Newfield, a pioneer researcher into winter hummingbirds in the Gulf Coast area and author of several books, including “Hummingbird Gardens: Attracting Nature’s Jewels to Your Backyard.”

“Her talk was all about hummers, and that’s what interested me at first,” said DiSalvo. “But now, I garden to attract as many different kinds of birds as I can. I’m not picky — I like all birds.”

DiSalvo will share her knowledge on Sunday, Oct. 11, the second day of the New Orleans Botanical Garden’s Fall Garden Festival.

Her talk, at 2 p.m. in the Garden Study Center, is one of five over the span of two days and is free with admission to the festival.

“The first thing you need to know is that you don’t have to have a big yard to attract a lot of different birds,” DiSalvo said.

You can make up for lack of space, she explained, by planning your yard or garden to ensure that birds have what they need to thrive.

“Basically, there are two types of birds that will visit — migrants and residents,” DiSalvo explained. “When birds are migrating in the spring and fall, they need places they can stop to rest and refuel on the way. They look for a safe place that provides them shelter — a thorny vine or a dense tree.

“They need a water source, too. If you’re serious about attracting the widest variety of birds to your yard, then you also want to plant native species because resident birds have adapted to them for food and shelter.”

Native plants are a boon to gardeners, because they aren’t fussy and don’t require a lot of care, DiSalvo added. Better still, they don’t tempt gardeners to use pesticides.

“Pesticides directly kill the food that the birds eat — insects, worms and caterpillars. They indirectly kill or harm birds when they ingest contaminated food,” she warned. “A sterile yard will not attract birds.”

Twice a year, about 40 percent of the world’s bird population migrates, heading north in the spring and south in the fall. The Mississippi Valley is one of four major “flyways” in the United States, she said, meaning a wide variety of nonresident birds pass through during those times. Migratory birds will stay a day or two before continuing their journeys.

“Teaching yourself to see birds takes a lot of practice,” said DiSalvo, a member of the Crescent Birding Club.

“When you are first starting out, you have to train yourself to listen,” she said. “When you hear something that sounds a little different, then you look for movement and use your binoculars.”

Shelter, water and food are the three primary needs of birds. Because some birds like the upper stories of tall trees and other, like to be close to the ground, DiSalvo recommends that gardeners plant in layers to attract the widest variety.

A bird bath (preferably shallow with running water), a misting device in a tree, a pond and a water drip are all water options that will suit birds, depending on their preference.

As for food, the more options gardeners can provide, the greater the diversity of birds it is possible to attract.

Hummingbirds need nectar, supplied by plants like bottlebrush, Turk’s cap, shrimp plant, cuphea and salvias.

Other birds go for worms and insects, often found in leaf and brush piles, or they go for berries on hollies and French mulberry trees. Bird feeders work as well, but DiSalvo offers a warning.

“I have seen cats sitting in bird feeders, waiting to catch birds,” she said. “Be careful, and keep your cats inside.”