It's the battle for New York's skies -- and feathers are flying.

On one side: jetliners from crowded airports. On the other: wild Canada geese. In a town that's not big enough for them both.

Ever since the 2009 collision between a flock of geese and US Airways flight 1549, followed by the "Miracle on the Hudson" crash landing, officials have had Canada geese in their sights.

At the start of each summer, teams from the US Department of Agriculture descend on parks like Inwood Hill in Manhattan to eradicate flocks of adult geese and their fluffy new goslings.

The geese are helpless. June to July is molting season, so they can't fly. It takes little time to put them in crates and drive them away to be gassed.

But thanks to David Karopkin and his fellow GooseWatchNYC activists, the big birds are not entirely alone.

Each day around New York, activists rise at dawn to watch over the urban flocks. If someone spots a raid starting, everyone in the GooseWatchNYC network is alerted via instant message.l

"It's horrifying," Karopkin, a 27-year-old lawyer in training, said. "I made a decision that I wasn't going to be asleep in my bed. I wanted to bear witness."

Another member of the goose brigade, 44-year-old writer Genevieve Mathis, starts at about 5:00 am, peeking from her window in an apartment that overlooks Inwood Hill Park.

"We can see the driveway and when they come, they come with eight or nine trucks," Mathis said. "We can spot them."

The activists won't physically prevent the USDA team roundups, but believe their presence and their filming of events is enough to give officials pause. And if the geese can just get through to mid-July, they'll have their wings working again.

-- New York: it's a jungle --

John F. Kennedy, LaGuardia and nearby Newark airports are home to huge fleets of planes crisscrossing the city skies at all hours. But New York is also surprisingly wild. Hawks nest among skyscrapers, there are coyote sightings, a rare frog population was discovered in the Bronx, and large areas of wetland shelter migratory birds.

Some 20,000 to 25,000 Canada geese live in the New York urban area, but that's about 20,000 more than there should be, according to Lee Humberg, district supervisor for the USDA.

"The targeted goal the department would like to see is 4,000 to 5,000. That's based on available habitat, nuisance complaints and other variable factors," he said.

The more immediate mission is simply to reduce flocks based within a five to seven mile range (eight to 11 kilometesr) of airports. During last summer's cull, crews were ruthlessly efficient, removing 575 of 654 geese observed at 11 locations, according to official figures.

In the US Airways crash -- which, amazingly, ended without a single victim -- a flock of geese, each the size of a small dog, smashed in without warning, knocking out both engines and sent the Airbus into the icy Hudson River.

"That was really the motivation that got people's attention," Humberg said in a phone interview.

Seagulls love the watery areas around airports like LaGuardia and also frequently hit planes, but the danger from geese is entirely different, Humberg said.

"The reason the Canada goose is an issue is their body size: they're over three pounds. Most jet engines are designed to resist a strike from a bird of three pounds or less," he said.

Humberg respects his feathery foes, describing the birds as hardy, highly adaptable and difficult to dissuade from their love of New York. "The overall trend is always up," he said.

Neither does he blame them for coming to the Big Apple.

"There's no hunting, no predators and we humans are building great yards that they love," he noted.

Karopkin calls the annual culls a waste of time, given that Canada geese are long-distance travelers and therefore could enter New York City airspace from any location.

"The idea that you can kill birds here and prevent (air accidents) makes no sense at all. It just takes one bird, so unless you kill every animal...," Karopkin said.

Officials say that in fact it's the resident geese, not migrating birds, that cause most airplane strikes.

But whatever the technical details, goose patrol volunteers believe they are standing up for the right thing.

"This is endemic to a whole American cultural problem: violence first, then protests, then -- maybe -- an intellectual solution," Rosemary Kliegman, 62, said.

Among ordinary New Yorkers, there are plenty who oppose Canada geese on a distinctly down-to-earth basis, namely the thousands of cigar-sized droppings that the animals leave in their path.

But Evelyn Rodriguez, walking five dogs through Inwood Hill Park, said that on this matter too, the geese are unfairly scapegoated.

"The cops ride their horses through here and they take big dumps," she noted. "No one picks that up."