WHY SING IN WINTER Marjorie Sorensen, tracking bird movements in a seasonally flooded valley in Zambia (left), is studying why great reed warblers (one shown, right) overwintering there sing so much.
L-R: Jason Boyce, M. Sorensen
PLAYING DEFENSE Random shifts in behavior could help disease-causing microbes like the bacterium Pseudomonas aeruginosa, pictured above, evolve antibiotic-resistance, a new study suggests.
MADE MALE This male mouse (white) has no Y chromosome, but was able to father pups (brown) when scientists injected his immature sperm into eggs. Researchers made the mouse male by manipulating genes on other chromosomes.