California migration of millions of birds brings ‘unprecedented’ avian flu threat

H5N1 strain, first detected in Europe, has spread rapidly across the country, and with no vaccine available, options are limited

Ever year during the fall migration season, 5.4 million waterfowl descend on California, as birds from Canada and Alaska make their way south on an aerial transnational highway known as the Pacific Flyway.

This year, the arrival of the birds also brings concern. A new avian influenza is circulating, and that means trouble for domestic chickens, wild birds and even mammals.