The modern equivalent of the passenger pigeon is the the red billed quelea which can form flocks that take 5 hours to fly past: http://en.wikipedia.org/wiki/Red

The modern equivalent of the passenger pigeon is the the red billed quelea which can form flocks that take 5 hours to fly past: http://en.wikipedia.org/wiki/Red-billed_quelea http://en.wikipedia.org/wiki/Red-billed_quelea