Think you're seeing the same bird over and over?

Human influence is producing uniformity, what a birder calls "the Wal-Martization of the American skies."

By DAN DEWITT
Published June 24, 2007

NEW PORT RICHEY - Ken Tracey tallied the plump, off-white birds perched on utility lines as he drove through a neighborhood in southwestern Pasco County.

"Collared-dove, " said Tracey, president of the West Pasco Audubon Society. "Mourning dove with a collared-dove right above it ... collared-dove ... another collared-dove."

So he saw plenty of birds, but mostly the same kind of bird, the Eurasian collared-dove. A native of Eastern Europe, it established a beachhead near New Port Richey 20 years ago, advanced across the continent and became one of the most common nonmigratory species in Florida.

Along with a handful of other species - including American crows and Canada geese - it has thrived because it can live comfortably among humans and feed on their handouts, according to a recent study by the National Audubon Society.

The populations of once common birds that live only in natural areas, meanwhile, have plummeted, the study found. It identified 20 species that have seen population declines of more than 50 percent in the past 40 years: pasture-dwelling Northern bobwhites, whippoorwills needing open forests, clapper rails that prefer salt marshes.

Though none of these birds is in danger of extinction, said the author's study, Greg Butcher, their dwindling numbers mean the same for bird life in the United States and Florida that it does for our landscape: more uniformity, less color and variety.

"In a way, it's the Wal-Martization of the American skies, " Butcher said.

* * *

Previous studies of bird populations depended mostly on the U.S. Geological Survey's annual breeding survey, conducted from the same roadside posts around the country every spring. Butcher's report is the first to combine these numbers with 40 years of records from Audubon's annual Christmas Bird Count, which tallies birds and species of birds after their fall migration.

The Christmas counts are not scientific surveys, but the database is valuable because it is so large. It's "50, 000 people reporting what they are seeing year after year, " Butcher said.

Also, it points to the same conclusion as the breeding census: The nation is losing vast numbers of birds - about 432-million among the 20 common declining species - and from every type of habitat.

Northern pintail ducks breed in "America's duck factory, " Butcher said, the small lakes and ponds in Canada and the northern United States.

These have been drained to make room for wheat and corn fields, he said, and the pintail population has dropped 77 percent in the United States and 96 percent in Florida since 1967.

Another duck species in decline, the greater scaup, summers in tundra degraded by global warming. The black skimmer's population has fallen because the birds nest on increasingly crowded Florida beaches.

Pasture species seem especially vulnerable, Butcher said. Pesticides and herbicides have killed the insects and weeds these birds eat. Frequent mowing leaves them without enough time to raise their brood, Butcher said, and "a lot of eastern meadowlark nests get cut down while they are still full of either eggs or young."

"These grassland habitats are much easier to develop in a variety of ways, " he said. "It goes to intensive agricultural uses and a lot of it goes to suburban development."

In one of the fastest growing parts of west-central Florida, southern Pasco County west of the Suncoast Parkway, you can almost see it happen.

"I just heard a bobwhite quail, " Tracey said, listening through an open window as he pulled off State Road 54 and parked next to a weedy, 20-acre pasture.

Stepping out of his minivan, he spotted two more birds on the Audubon's list of declining species: a loggerhead shrike that scanned the meadow for grasshoppers to impale with its beak and a meadowlark on a fence post that turned its head, showing off its bright-yellow neck.

But Tracey also pointed out the two subdivisions and the cemetery bordering the field.

"You can see how crammed in this is, " he said. "This is not going to be overgrown pasture much longer."

* * *

This kind of growth means the national trend toward declining bird populations is especially pronounced in Florida, Butcher said.

"The development pressures are just so much stronger there than in the rest of the country."

The numbers of many of the 20 common species in decline across the United States have dropped even more dramatically in Florida. The survey identified 49 species in Florida with population losses of more than 50 percent.

Even the good news about birds in Florida is tainted. The rufous hummingbird, in steep decline nationally, has made astounding gains in Florida, with its migratory population climbing about 700 times since 1967, according to bird count statistics.

This, however, is due to deforestation in Mexico, the bird's historic migration grounds, and global warming that allows the birds to winter on the Gulf Coast.

Finally, the state is home to the survey's most unwanted success story, the Eurasian collared-dove.

The species arrived in Florida after a few were released in the Bahamas in 1972, said Bill Pranty, a biologist with the Florida Fish and Wildlife Conservation Commission and one of the state's most accomplished birders.

Though the species first came to the state in the late 1970s, the first documented sightings during Christmas counts came in 1986 in Key Largo and near New Port Richey.

"I remember finding them with my friend and we said, these are not ringed turtle-doves, these are collared-doves, " said Pranty, who saw the birds in a small coastal neighborhood, Baillie's Bluff, a few days before the count.

"We were sort of surprised, but interested to see them in Pasco County."

Collared-doves are no longer a novelty, with 270 tallied in the 2006 West Pasco Christmas count compared to 29 common ground-doves, a native species. Though Pranty has seen no evidence that the collared-doves have displaced other birds, their rapid spread has made them "a symbol of how humans have altered habitat, " Butcher said.

"They have sort of a mournful, three note call ... What I think of is: 'No hope, duuude. No hope, duuude.' "

* * *

If there is hope, it is in the resiliency of birds. Small changes in their habitats and humans' habits can stem these declines or begin to restore their populations.

Black skimmer mothers do not warm their eggs during hot days, they shade them, said Julie Wraithmell, wildlife policy coordinator for Audubon of Florida, and teaching people to stay clear of nesting birds could save thousands of young.

"People need to know that eggs can cook in the Florida sun very quickly, so some of these disturbance events are catastrophic for entire colonies, " she said.

Bev Hansen, an avid birder from Hernando County, has noticed a side benefit of the controlled burns intended to benefit endangered red-cockaded woodpeckers in Withlacoochee State Forest.

Native wire grass has flourished, Hansen said, "and now I hear bobwhites all the time."

Even the spread of the collared-doves has contributed to the rise of a distinctive predatory species.

"There goes a Cooper's hawk looking for a collared-dove, " Tracey said, watching the small hawk skimming above a mangrove forest just north of Baillie's Bluff.

"That's one good thing. The Cooper's hawk population has gone up 10 times because of the collared-doves."

Dan DeWitt can be reached at dewitt@sptimes.com or (352) 754-6116.

On the rise

These birds have thrived between 1967 and 2007, the period studied in a recent National Audubon Society population survey of U.S. birds.

AMERICAN CROW

Black plumage and beak. Florida: 5 percent decrease; U.S.: 1, 300 percent increase. Keys to survival: able to thrive in both agricultural and urban areas, eating nuts, seeds, garbage and carrion.

CANADA GOOSE

Large, long-necked goose with white breast patch. Florida: 418 percent increase; U.S. 1, 500 percent increase. Keys to survival: benefited by widespread restoration efforts. The birds will eat corn and bread crumbs from humans and live in artificial lakes and ponds.

DOUBLE-CRESTED CORMORANT

Large, dark waterbird with a long, hooked bill. Florida: breeding population is stable, migratory population increased by 239 percent. U.S.: increased 2, 100 percent. Like the bald eagle, they have emerged from near extinction caused by DDT and eat a wide variety of fish species.

EURASIAN COLLARED-DOVE

Pale tan and gray coloring with a black collar. Increase in Florida and U.S.: After migrating to the United States in the 1970s, collared-doves have become one of the most common nonmigratory birds in Florida and have spread to more than 20 states, including California. Key to survival: prefers to perch on utility lines and poles; eats seed from feeders and weedy lots.

On the decline

The following birds are among the 20 species with populations that have dropped more than 50 percent in the past 40 years.

EASTERN MEADOWLARK

Robin-sized bird with light-brown back and brilliant yellow breast. U.S.: declined 72 percent; Florida: declined 90 percent. Key to falling population: loss of grassland habitat due to development and intensive agricultural practices.

NORTHERN PINTAIL

Mallard-sized duck with a slim body found in grassy uplands and untilled cropland. U.S.: declined 77 percent; Florida: declined 96 percent. Key to falling population: draining of small ponds in northern U.S. and Canada and warmer northern winters that mean fewer ducks migrate to Florida.

NORTHERN BOBWHITE

Chubby, robin-sized quail found in grasslands mixed with shrubs. U.S.: declined 82 percent; Florida: declined 96 percent. Key to falling population: loss of grasslands and replacement of native grasses with imported species.

LOGGERHEAD SHRIKE

A songbird with black wings and a light-colored chest that hunts large insects, mice and even other small birds. U.S.: declined 71 percent. Florida: Breeding population has declined 82 percent, migratory population by 43 percent. Key to falling population: decline of pasture habitat.

[Last modified June 24, 2007, 02:31:29]