This monster plant is taking over Silicon Valley -- should we let it?

It's about 15 minutes before sunrise, and we're standing in the middle of a marsh listening for a bird call that sounds like TV static. The call belongs to the endangered California Ridgway's rail, a plucky but shy marsh-dwelling bird. The rails are both the heroes and antagonists of a conservation paradox that's unfolding here in the San Francisco Bay. The ecologists we're shadowing are trying to save the birds, but they're also trying to eradicate the invasive grass that the birds have come to...