Garden Allies: Gleaners among the Birds

By: Frederique Lavoipierre
frederique

Frederique Lavoipierre is Education Program manager at Santa Barbara Botanic Garden. She also teaches classes and workshops on many aspects…

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Anna’s hummingbird (Calypte anna). Illus: Craig Lakter

More Than Just Beauty and Song

Standing at my kitchen sink one day, I watched a hummingbird hovering alongside a spider web that stretched between an old rose and the nearby windowsill. I knew that hummingbirds favor spider silk to line their nests, but it soon became clear that this bird was picking insects from the web-using it as a convenient “pantry.” That day, I learned that hummingbirds, well known as nectar-feeders, also eat insects, and can often be observed gleaning aphids and other small arthropods from plants.

Any conversation on attracting birds is sure to produce a lively debate among gardeners. Yes, my pea seedlings have been systematically pulled from the ground on more than one occasion, and I have lost my share of berries to birds. But overall, birds add an essential, beneficial, and aesthetic element to any garden. While most birds eat a varied (omnivorous) diet, birds that eat insects for at least part of their lives account for eighty to ninety percent (and sometimes more) of bird species in most areas. Some birds seek out insects only during the breeding season, when protein becomes a necessity. Coincidentally, breeding season for birds, late spring and summer, is exactly when many insects and other arthropods are causing trouble for gardeners.

Bushtit (Psaltriparus minimus) Illus: Craig Latker

Varied Diets and Feeding Styles

Ecologically, birds can be categorized by their diet and method of obtaining food. Some glean insects and other arthropods directly from plants or on the ground. Another group of birds catch arthropod prey on the wing. Raptors help keep the rodent population under control. Of course, not all birds fit neatly into a category. Orioles glean from leaves, but also catch insects on the wing. Hummingbirds can snatch fruit flies in midair, in addition to gleaning insects from foliage, flowers, and spider webs, and they don’t perch, or give aerial chase, but hover. Since this series explores garden allies, we will bypass aquatic birds, and those that eat only seeds, fruits, and nuts. This first of three articles focuses on birds that find insects primarily by gleaning

Gleaners show preferences for specific parts of plants. Warblers and bushtits, for instance, pluck insects from foliage. Titmice, chickadees, and nuthatches pick insects from crevices in bark. Woodpeckers and flickers probe the trunks and main branches of trees. Towhees find insects in litter on the ground. Warblers, tanagers, and grosbeaks like to feed on insects in foliage in the high canopy of trees, whereas sparrows, jays, and some other ground-gleaners will venture into low vegetation to search for insects. Many gleaners will make an exception for a tasty morsel and occasionally give chase on the wing.

Some gleaners, such as wrens, vireos, nuthatches, and creepers, are almost exclusively insectivores. Most insectivorous birds eat a variety of insects, but some have more specific tastes. Orioles, for instance, love to eat wasps, a boon for backyard picnickers with yellow jackets in the vicinity. Warblers have a varied insect diet and employ multiple feeding methods. Jays are omnivorous, but insects are a significant component of their diet, especially during nesting. Juncos are primarily seedeaters, but feed their young insects. Many seedeaters relish an occasional insect. The goldfinches that cling to swaying stems of cosmos in the fall also eat insects as they pluck off seeds. Quail eat insects as they look for the leaves and seeds they prefer. Robins eat insects as well as worms.

Welcoming Birds to the Garden

Creating year-round habitat for birds is crucial to a well thought-out pest management program. Birds that eat pesky insects are sometimes migratory, but, more often, they are resident birds and need food, shelter, and water to remain in the area year-round. Many birds like to land on a tall object, such as a tree, from which they can survey the safety of their surrounds. They can then move down the “ladder” to shrubs, tall perennials, and the ground. Although a birdbath tucked into a border will enjoy use, one set into an opening will likely have more visitors. Birds require different nesting zones and types of shelter. A garden with a diversity of trees and shrubs (thorns are favored) will soon be occupied. A mixture of deciduous and evergreen shrubs is ideal. If your garden has room, a brush pile provides good bird habitat for a number of desirable garden birds, and an old tree snag will attract many inhabitants.

Hold back on the deadheading, especially in the fall, and let birds feast on seeds (and the insects that eat those seeds.) Attractive berry- and fruit-bearing plants are easy to include in gardens. Many birds enjoy pecking around tufts of bunch grasses for food. First, find out which birds are likely to live in your neighborhood, and choose plants that will provide suitable food and habitat. When you do see insects, they are likely to be quickly dispatched by hungry birds. Sound is an oft-overlooked garden element, but the sound of dripping or bubbling water is particularly attractive to birds. An open window allows bird songs from the garden into our home. A beautiful and diversified garden will be satisfying to both human and avian inhabitants.

Red-shafted flicker (Colaptes auratus) Illus: Craig Latker

In a Nutshell

Popular Name:

Most of the birds listed here are collectively known as perching birds or songbirds—passerines (Order: Passeriformes), which includes over half of all bird species. Quail are an upland game bird.

Scientific Name:

Birds in the text belong to the following families: Phasianidae (quail), Trochilidae (hummingbirds), Picidae (woodpeckers and flickers), Vireonidae (vireos), Corvidae (jays), Paridae (titmice, chickadees), Aegithalidae (bushtits), Sittidae (nuthatches), Certhiidae (creepers), Troglodytidae (wrens), Turdidae (robins), Parulidae (wood-warblers), Sylviidae (old-world warblers), Cardinalidae (grosbeaks), Thraupidae (tanagers), Emberizidae (juncos, towhees, sparrows), Icteridae (orioles), Fringillidae (finches), Passeridae (old-world sparrows). This is not an exhaustive list of all common insect-eating gleaners.

Common Garden Species:

Most of the species discussed are common in gardens. Orioles, tanagers, woodpeckers, and flickers may be less commonly seen in urban gardens, but are not rare. Many species can be attracted with suitable habitat and food.

Distribution:

Many garden birds have a wide distribution along the Pacific Coast; some may be only seasonal visitors.

Life Cycle:

All birds lay eggs, usually in the spring, when food is abundant; some may produce more than one brood in a year. Even birds that are not insectivorous will often feed their young high-protein insects.

Appearance:

Winged and feathered with two feet! Often have distinctive markings. Many insectivorous birds are quite small, and continually active, as they search for food.

Life Span: 

Varies widely: while most passerines do not live more than one or two years in the wild, birds that survive their first year may live for several years. Larger birds often live longer than smaller birds.

Diet:

Birds may be completely insectivorous, eat a widely varied diet, or eat insects only occasionally. While some birds are indiscriminate in their choice of arthropods, others
specialize on specific insect orders.

Favorite plants:

Thorny plants (for nesting‚), fruiting and seed-bearing plants, conifers and deciduous trees all offer valuable resources for birds. Choose suitable plants for locally resident birds.

Benefits:

Voracious insectivores.

Problems:

May occasionally eat garden crops or flower buds and cause damage to garden plants.

Interesting facts: 

The shape of a bird’s beak corresponds to its diet. Woodpeckers and flickers have a long, hard beak for probing branches. Woodpeckers are also equipped with a long, extendable tongue for probing insect galleries; the tongue may be three times the length of the bill, wrapping around the skull when not in use. Hummingbirds lay the smallest bird eggs, about the size of a pea.

Sources: 

Birds are natural visitors in most gardens.

More information: 

The Sibley Guide to Birds, National Audubon Society, 2000: a reference for identification and distribution.

The Birder’s Handbook, by Erlich, Dobkin, and Wheye, 1988: natural history, including diet and habitat.

http://www.theodorepayne.org/mediawiki/index.php?title=Birds

www.nwf.org/backyardwildlifehabitat

www.eNature.com/garden_birds