Birds a common airport threat 

Source: ReutersPassengers stand on the wings of a US Airways plane as a ferry pulls up to it after it landed in the Hudson River in New York

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It's believed that the US Airbus that crash-landed in New York's Hudson River was hit by birds, a hazard more common for aircraft than you might think, in New Zealand as well.

The US Airways flight 1549 with 150 passengers and five crew aboard was bound for Charlotte, North Carolina, from New York's LaGuardia Airport. The pilot made an emergency landing in the river just minutes after take off.

None of the 155 people on board were seriously injured, officials said, despite the frigid conditions and the river's swift current.

At Auckland Airport up to 15,000 birds can gather during the peak summer migration period, and some flights have had to be held up to let flocks of birds cross the runway.

Four years ago, ONE News captured dramatic footage of a bird flying into the engine of a Pacific Blue aircraft in Christchurch, and an Air New Zealand Boeing turned back to Auckland 18 months ago after hitting some geese.

Auckland Airport has around 50 hits, or near misses, every year, but that is pretty small compared to the number of flights.

The highest risk airport is Gisborne, followed by Invercargill and Napier.

A lot of research goes into how birds affect jet engines but scaring them off is the best method.

Auckland Airport employs a full-time bird patroller who uses a portable gas cannon to scare birds off and they also grow special vegetation to discourage birds.

However, bird strikes have been responsible for only a few hundred deaths in the history of aviation.