Protecting backyard birds

MANY WILDLIFE DISEASES are seasonal. Bird flu spreads most virulently in winter and early spring. The botulism and salmonellosis that affect backyard birds tend to strike at winter’s end, spreading as snow melts until lush vegetation covers the wasted seed and animal droppings that collected on the soil in winter. Mosquitoes transmit West Nile virus, which peaks in temperate climates from July to October.

West Nile virus was unknown in the Americas until 1999. Some North American birds are far more vulnerable to