Potential health effects
Methane is not toxic. The immediate health hazard is that it may cause burns if it ignites. It is highly flammable and may form explosive mixtures with air. Methane is violently reactive with oxidizers, halogens, and some halogen-containing compounds. Methane is also an asphyxiant and may displace oxygen in an enclosed space.

en.wikipedia.org...

Originally posted by antmax21
There is something in the air coming from below. Of course we know gas rise, liquids fall, so thus it is a gas. No viral infections no subtle changes in organs and convulsions lead to the conclusion that the cause of the bird deaths is still unconclusive...

Check some links on Methane

Methane and The Digestive System

Maybe has some points on why some birds are dying.

Originally posted by Speedtek
I'm willing to bet this is the culprit,

In fact, one of the major sources for increased methane venting is the Hudson Submarine Canyon, which extends 400 miles into the Atlantic from the New York-New Jersey harbor. Another location experiencing increased venting is the Santa Barbara Channel on the California coast.

From another source.

Methane is odorless so it wouldn't be directly responsible for the stank that New York City and Jersey City experienced Monday, but when the methane starts bubbling up to the surface it is often accompanied by hydrogen sulfide, a byproduct of the bacterial decomposition that occurs on the ocean floor. And the Hudson Submarine Channel would be particularly susceptible to extra-stinky decomposition, as many speculate it is still covered with the sludge and trash of several centuries of the inhabitants of New York City dumping their garbage and sewage directly into the harbor.

And finally to put a nail in the stinky coffin of where this is coming from.

Hey, look, the wind was coming in from the east (the direction of the trench) that day!
Wind Direction & Weather

I'm quite sure our gov knows about this, but why is there no mention of it in the general media?? Go figure! Its alot easier just to blame it on New Jersey.

From a news.com.au article on the subject. -- seems some of you guys have made an impact

The story has resonated well with conspiracy theorists however, who have rejected the temperatures or toxins and instead have fingered a host of sinister-sounding technologies or occurences to explain the phenomenon, extending all the way to the “environment warning of other things going on that can’t be seen,” according to one post on NEWS.com.au.

They've also learned what happens during a magnetic flip. Reversals take a few thousand years to complete, and during that time--contrary to popular belief--the magnetic field does not vanish. "It just gets more complicated," says Glatzmaier. Magnetic lines of force near Earth's surface become twisted and tangled, and magnetic poles pop up in unaccustomed places. A south magnetic pole might emerge over Africa, for instance, or a north pole over Tahiti. Weird. But it's still a planetary magnetic field, and it still protects us from space radiation and solar storms.

Methane is continuously produced in manure pits and released into the air at a steady rate. A colorless, odorless, non-toxic gas that is lighter than air, methane generally dissipates from a confinement building. The primary danger of methane accumulation in a facility is the risk of a fiery explosion from a spark if the methane/oxygen mix is in proper proportions. The risk of fire is greater in a poorly-ventilated structure.

Although non-toxic to humans and livestock, methane can cause asphyxiation if it displaces the oxygen in a closed facility.