Science: Animal Trackers

Viruses dog birds—and dogs

All things considered, these are not the best of times to be a chicken. First the searing heat over much of the nation this summer killed nearly 10 million birds, or about 1% of the 1.25 billion commercial chickens alive and scratching in the U.S. at any one time. Drought drove up grain prices, making the fowl more expensive to feed and buy. Now comes still another peril: so-called exotic Newcastle disease, a viral disorder that attacks chickens as well as a wide variety of other birds.

The symptoms: gasping and coughing, often followed by nervous disorders. Upon taking...