Million swallows roost on California farm

TRACY, Calif. — In a Central Valley cornfield, a swarm of tree swallows is roosting nightly, fattening up by day for a migration as far south as Central America.

The rare nightly gathering of between half a million and 1 million of the songbirds is luring a growing crowd to the flat fields of Tracy.

Bird watchers and scientists are breathless over the discovery of what is believed to be only the third large-scale roosting spot for swallows west of the Rockies.

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