Natural Perspectives -- Vic Leipzig and Lou Murray

Vic Leipzig and Lou Murray

In the spring, a river of songbirds flows over Huntington Beach. We

see only a small percentage of the thousands of birds that fly through

because they travel mainly at night, flying half a mile to a mile above

us. By day, some of them alight in our parks and yards to rest, find

food, and take a drink.

These birds are called Neotropical migrants because they travel from

their wintering grounds in the Neotropics, which are tropical regions of

the New World, to their breeding grounds in North America. Neotropical

migrants encompass some of our most beautiful songbirds and include

warblers, tanagers, orioles, and vireos.

This pattern of wintering in the tropics and summering in the north

was established between 10 and 30-million years ago. Over the eons, birds

developed ways to navigate over unfamiliar terrain, but exactly how they

do it remains a mystery. Scientists believe that migrants navigate by a

variety of methods that include using the position of the sun and stars,

magnetic iron in their skulls, visual landmarks, and learning from other

birds.

Recently, the trees in Huntington Central Park were alive with Hermit

Warblers as a wave of them swept through town. Hermit Warblers winter in

Central America and southern Mexico, flying north in the spring to breed

along the coast in Washington and Oregon. We get a chance to see them

only briefly during migration.

One of these tiny birds would barely fill a person’s palm, yet they

make their remarkable 4,000 to 5,000-mile journey in a matter of weeks,

flying at 20 to 30 miles per hour all night long. Somehow they find food

and water along the way, and, if they’re lucky, avoid predators and other

hazards. They enjoyed a feast this year in Central Park eating lerp

psyllids, a tiny pest that is infesting eucalyptus trees.

Another of our migrants, and one of the prettiest, is the Western

Tanager. Larger than a warbler, this gorgeous bird has a yellow body with

black wings and back and a bright red head. One flew into our yard this

week, attracted by our pond. A stranger to our yard, it looked around

cautiously before dipping down to the water’s surface to drink. Later,

when it was more comfortable with its surroundings, it took a lengthy

bath.

Warbling Vireos are flying through right now. Unlike other species

that stand in our pond and splash, the vireos only touch the water’s

surface, taking a dip on the wing. We’ve never seen them luxuriate in a

bath like other species.

Swainson’s Thrushes, which are brown, robin-like birds with heavily

streaked breasts, also migrated through in large numbers recently.

These bird species have several things in common. They all winter in

Mexico or Central America. They’re all just passing through. And they all

eat insects.

In recent years, birders and scientists have noticed a dramatic

decline in the number of Neotropical migrants. Causes include loss of

food and shelter on their wintering grounds due to logging in Central

America, loss of breeding habitat due to logging in the Pacific

Northwest, and loss of habitat along the migration route. There are also

hazards during migration. Birds hit skyscrapers and windows and die by

the thousands. Predators such as outdoor cats eat many of them.

Another big problem for migratory birds is use of insecticides.

According to the American Bird Conservancy, 1.2 billion pounds of

insecticide are used in the U.S. each year. This is more than 20% of the

world’s total usage. The U.S. Fish and Wildlife Service estimates that

672 million birds are exposed directly to agricultural insecticides each

year. And 10%, or 67 million birds, die from this exposure. It gets

worse. Homeowners apply four times as much pesticide per acre as farmers.

Think how many birds must be killed by home use of insecticides.

When we see shelf after shelf filled with insecticides at local

nurseries, hardware stores, and home improvement outlets, we worry about

the affect these chemicals will have on Neotropical migrants. Birds need

insects to eat while they’re flying north. Killing off insects greatly

reduces their food source. Birds also can be killed directly by

insecticides, either by short- or long-term exposure. Even if they aren’t

killed outright, birds can suffer neurological damage. This makes them

more likely to fall victim to predators, fly into cars or buildings, or

develop behaviors that make them less successful at breeding.

All those pounds of insecticide aren’t good for the birds. They aren’t

good for the ocean and Bolsa Chica wetlands, which is where insecticides

go if water flows off lawns and into storm drains. And you know what?

Insecticides aren’t good for humans either.

After flying hundreds of miles each night, migratory birds need a safe

spot in which to rest, feed, and drink. Many people have made lifestyle

changes to help migratory songbirds. They buy organic produce at the

Farmers’ Market downtown to encourage less use of agricultural

pesticides. They avoid insecticides in their yards, using ecologically

sound alternatives to rid their yards of pest insects. They landscape

with native plants to encourage desirable insects such as dragonflies,

ladybugs, and butterflies. And they create water features for birds to

use for drinking and bathing.

Making these changes can help ensure that future generations will be

able to enjoy the mystery of bird migration, an ancient pattern that is

in jeopardy.

* VIC LEIPZIG PhD and LOU MURRAY PhD are Huntington Beach residents

and environmentalists. They can be reached at o7 [email protected] .