A word of warning about bird-feeding

VIC LEIPZIG AND LOU MURRAY

All over the world, birds are getting hit hard by various diseases.

In Asia, two separate viruses -- bird flu and avian flu -- are

attacking domestic poultry. There is concern that these viruses may

jump species and infect humans, causing a pandemic.

Here in the U.S., West Nile virus is taking a heavy toll on wild

birds, especially crows. Newspapers have reported dead crows dropping

out of the sky like flies in Los Angeles and San Bernardino counties.

People can become infected with West Nile virus from mosquito bites

or from coming into contact with the blood or saliva of a dead or

infected bird.

Now, there is yet another bird epidemic to worry about.

Fortunately, this one affects only birds, not humans. The culprit in

the latest epidemic is a flagellated protozoan called Trichomonas

gallenae. The disease it causes is called trichomoniasis, or canker.

Its effect on doves and pigeons is especially deadly. One concern is

the effect it will have on Southern California’s band-tailed pigeon

population. In 1988, at least 16,000 of these birds were killed by

this disease. Additionally, trichomoniasis can spread to and kill any

raptors that feed on the infected doves or pigeons. In raptors, the

disease is called frounce.

When the protozoa infect birds, the result is really gross. The

pictures we saw on the Internet were enough to gag a goat. The birds

get large, cankerous growths inside the mouth and esophagus. The

cheese-like growths become so large that they block the esophagus,

and the birds cannot swallow. Birds die of either starvation or

suffocation.

The disease can be passed from parent to offspring during feeding

or from one adult to another during courtship. The disease can also

be passed by contaminated seed or water, which is what has backyard

birders worried.

Many people enjoy feeding birds in their yards. As natural areas

decline due to urbanization, food supplementation with seed feeders

can be a boon to birds. But the birds that come to backyard feeders

in our area are generally those that have adapted to an urban

environment and are often introduced species. Backyard feeders in our

town are probably of more benefit to human observers than to Southern

California’s native wildlife.

In Huntington Beach, usually mourning doves, rock doves, house

sparrows and house finches come to mixed-seed feeders. Since

trichomoniasis can spread rapidly through birdbaths and contaminated

seed, we’ve received e-mails from worried bird lovers wondering what

to do.

Here is what we found when we researched the topic. These protozoa

have been in this country for hundreds of years, and they haven’t

wiped out the pigeon and dove populations yet. Trichomonas was

probably brought to the New World in the 1600s, along with domestic

pigeons. Birds and the protozoa have coexisted here since then.

Indeed, some studies have shown that 80% to 90% of some pigeon flocks

are infected with the protozoa, usually with no ill effects. However,

an especially virulent strain of the protozoa occasionally develops.

In California, there are outbreaks of trichomoniasis annually. An

outbreak among mourning doves was reported in Yucca Valley and the

Coachella Valley in May of this year. Earlier this month, it was

reported in band-tailed pigeons in the Los Padres National Forest in

the Santa Barbara area. So far, it doesn’t seem to be in coastal

Orange County.

Wildlife officials with the Department of Fish and Game suggest

people should either bleach their feeders and birdbaths with a

solution of 10% bleach on a daily basis, or stop feeding birds

altogether. The protozoa can live up to five days on moist grain and

can survive for anywhere from 20 minutes to several hours in a

birdbath, but bleach will kill them. Another strategy is to move

feeders around to avoid buildup of contaminated seed in one location.

They say that by the time you see sick birds at your feeders, the

disease has already spread. Their main concern is the spread of the

disease to band-tailed pigeons, a species of the foothills and

mountains rather than the coast.

Our advice is to not worry about trichomoniasis here in Huntington

Beach. The disease seems to be more prevalent inland. Follow good

hygiene with feeders and keep birdbaths clean and fresh, but being

fanatical about daily bleaching of seed feeders and birdbaths is

probably not necessary.

We are taking the precaution of offering only sunflower seeds this

summer, which attract mainly house finches. We are not offering a

millet seed mix, as we usually do, as this mix attracts mostly doves,

pigeons, starlings and house sparrows. When Jan Smith opens her Wild

Birds Unlimited store at Beach Boulevard and Adams Avenue later this

month, we’ll get a thistle feeder for goldfinches and maybe add

another hummingbird feeder. Our yard will not be without birds.

Our more medically versed readers may recognize trichomoniasis as

a sexually transmitted disease of humans. But the protozoa that

causes the human disease is Trichomonas vaginalis, a different

species of protozoa in the same genus. Don’t worry, you won’t get a

sexually transmitted disease from birds at your feeders. However,

don’t touch any dead or diseased birds. West Nile virus is definitely

on the coast, and it is contagious to humans.

* VIC LEIPZIG and LOU MURRAY are Huntington Beach residents and

environmentalists. They can be reached at vicleipzig@aol.com.