Nightlife: Marsupial meets mistletoe

That’s no bird—that’s a marsupial. But it’s doing a fine job of what was thought to be a bird’s task: dispersing mistletoe seeds.

The nocturnal, squirrel-size Dromiciops australis eats seeds of a South American mistletoe and then excretes them onto trees, report Gillermo Amico and Marcelo A. Aizen of the Universidad Nacional del Comahue in Rio Negro in Argentina. When deposited, 98 percent of the mistletoe seeds eaten are intact and ready to sprout, the researchers report in the Dec. 21/28 Nature.

Mistletoes parasitize other plants, and most mistletoe seeds need to catch rides to new host plants. In most cases, birds serve as the on-time carriers (see “Botany under the Mistletoe,” in this week’s issue: Botany under the Mistletoe). But in the 500 hours that the scientists staked out the plant, no birds ate the South American mistletoe, Tristerix corymbosus.

The researchers note that this species blooms at an odd time, from the austral fall through the winter, when their marsupial carriers are particularly abundant. These mistletoes could easily have been feeding ancestors of their current marsupial carrier for some 70 million years, the researchers say.

Susan Milius is the life sciences writer, covering organismal biology and evolution, and has a special passion for plants, fungi and invertebrates. She studied biology and English literature.