Jeanna Bryner, livescience.com 16 Jan 09;
At a time when scientists are sounding ever more frequent alarms on the potential extinction of this creature or that, yesterday's collision with a flock of geese that put an airliner in the Hudson River is a reminder that some species are doing just fine.
Many birds have been faring well in the United States, even in urban environments (and in some cases especially in them), over the past few decades, say two bird experts and conservationists.
"Birds are increasing and that's good," said Kevin McGowan of the Cornell Laboratory of Ornithology in New York. "People have worked hard to do that kind of thing. Most people like it. We don't always hear enough about the fact that a lot of things are doing well."
McGowan notes that on an individual species basis, some bird numbers are going up and of course some are going down. Resident Canada geese, one of the species that is more likely to be involved in so-called bird strikes with aircraft, are particularly thriving, he said today, which is in part due to conservation efforts.
And the same has been seen with bald eagles. The number of breeding pairs in the lower 48 states increased from nearly 500 in 1963 to nearly 10,000 in 2006, according to the U.S. Fish and Wildlife Service, which attributes the comeback to the U.S. ban in 1972 of the pesticide DDT, along with the bird's protection under the Endangered Species Act.
Migrating vs. staying put
While most of the 11 subspecies of Canada geese migrate to the Arctic and sub-Arctic regions to nest, the resident Canada geese usually stick around in the lower 48 states.
The total number of resident Canada geese in the United States is about 3.2 million and has increased dramatically during the past several decades, according to the U.S. Fish and Wildlife Service. Any golfer could tell you this, as some golf courses have become a favorite place for Canada geese and other water fowl. Even at a desert course, such as in the Phoenix metro area, manmade lakes help attract hundred of birds that, annoyingly for some who tire of their droppings, never leave.
"A lot of it is from our conservation efforts. We've put in a lot of effort into making things better for birds," McGowan told LiveScience. "And [Canada geese] are very good at dealing with urban situations. Birds are adapting to it, and people are helping them along the way, which again is a good thing."
Terry Liddick, a Fish and Wildlife Service flyway biologist, said over the past 10 years the resident Canada goose population has slightly increased, at least by a few percent.
Geese and other birds living in urban areas of course puts them potentially in the path of low-flying aircraft.
"Airports have all kinds of programs to try to alleviate bird hazards around runways," said Dale Oderman, associate professor of aviation technology at Purdue University in Indiana. "They try to make the habitat unfriendly for birds. So that's why you don't see lots of trees around airports, because trees are nesting places for birds." He added that at some airports, dogs are used to chase away birds or blank weapons are fired to scare birds away.
Comeback era
After the industrial revolution when vast swaths of trees east of the Mississippi were cut down, the environment saw an uptick as trees were planted, laws to protect birds such as the Migratory Bird Treaty Act came online, and bird-conservation organizations such as the Audubon Society were established.
McGowan just finished co-authoring "The Second Atlas of Breeding Birds in New York State" (Cornell University Press, 2008), in which scientists compare bird populations from 20 years ago with their numbers now. About half of the bird species showed a change in numbers, and of those, more showed an increase rather than a decrease, he said.
Birds that are thriving in the New York area and in some cases elsewhere in the United States, he said, include resident Canada geese, eagles, peregrine falcons, Cooper's hawk, great blue herons, wood ducks and osprey.
Of course, not all birds are thriving. Since 1967, the average population of some of the most common North American birds has fallen, according to the Audubon Society. For instance, since 1967, the Northern Bobwhite population has decreased by 82 percent, while the robin-sized Evening Grosbeak has taken a 78 percent nosedive.
And following the introduction of the West Nile Virus in North America, several bird species, including the American robin and the Eastern bluebird, suffered significant declines, according to the Smithsonian's Migratory Bird Center.
McGowan does note that for those soaring bird populations, more birds could mean more hazards to humans. But he thinks of yesterday's incident as a random event, not as a result of growing bird populations. The ditch landing reportedly was the result of birds striking the Airbus 320's two engines, although the details are still under investigation.
"There are some costs that come along with it," he said, referring to growing numbers.
"The populations are increasing for a bunch of birds, but that probably has nothing to do with this air strike. I don't want to speculate on what's going on before all the facts are in."
Birds have long been a known and common hazard for airplanes. In fact, the first such strike was reported by the Wright brothers. Nowadays, bird strikes are more common. From 1990 to 2007, 82,057 wildlife strikes with civil aircraft were reported to the Federal Aviation Administration, with nearly 98 percent due to birds. The number of such strikes annually has more than quadrupled from 1,759 in 1990 to a record 7,666 in 2007, according to the FAA.
McGowan added, "There are lots and lots of birds out there and they're a known hazard to aircraft; the government spends a lot of time trying to avoid them as best they can. This is a freak accident and it may never happen like this again. It's not like necessarily you can point to 'There are too many geese.' It's one of those rare fluke events."
