Scientists and veterinarians are racing to prevent a wildlife disaster from getting worse in Tulare Lake, where hundreds of birds are dying from avian botulism in its stagnant waters.  The lake that reemerged in the San Joaquin Valley during winter flooding, which was partly brought on by snowmelt, after decades of dormancy has become a warm and stagnant breeding ground for toxins that cause paralysis and death. It’s common for avian botulism to strike water fowl when temperatures rise in summer and fall. But in 1983, the last time Tulare Lake emerged to such a large size after winter flooding, the disease killed more than 30,000 birds.