A United Airlines plane struck a bird as it was about to land in Denver yesterday, ripping a large hole in the nose. The plane landed safely and none of the 151 passengers or crew was injured. The pilots declared an emergency the instant the bird was hit. The bird's remains were recovered from the aircraft and are being examined to determine the species, reports ABC. Airliner engines are currently designed to be capable of "ingesting" birds weighing up to four pounds with no significant effect, but many birds are larger. The number of plane animal strikes has jumped from 1,800 in 1990 to nearly 10,000 in 2010, with birds accounting for 97% of those.