MARYSVILLE, Calif. -- Tens of thousands of tiny toads have been hopping across streets, lawns and patios in a neighborhood of Marysville, Calif., this spring, and scientists say it's partly because of the California drought.

It started about three weeks ago in the neighborhood, which is in close proximity to a small drainage basin that collects rain runoff during the winter and spring. Neighbors told reporters with TV station KCRA that it's the first time they can remember the basin being bone dry.

Dale Whitmore, a California Department of Fish and Game biologist, said the drought killed all of the fish in the lake. Without any fish to eat the toads' eggs, the population exploded.

The western toads are now about the size of a quarter and range in color from gray to brown to green. By the end of the summer, they will be about the size of a human fist.

By then, Whitmore said, their numbers will likely be dramatically reduced, as they are eaten by cats and birds or killed trying to cross nearby streets and railroad tracks.