Formosan Squirrels

September 14, Kamakura City, Japan

These Formosan squirrels are sneaky, lying little bastards. At first, they appear to be quite the altruistic species, working in mob-like teams to fend off any intruding snakes. If a snake, like Elaphe climacophora, is caught crossing into their territory of branches, an alarm is sounded that resembles a human scream that can be heard from 200 meters away. Every squirrel in the area gathers around the snake to harass it until it finally retreats down the tree.

Aerial predators, Spilornis cheela or Butastur indicus for example, are also cause for a warning call. This vocalization is different and instead of assembling together, the squirrels go into hiding and remain silent until the threat has passed overhead.

Male squirrels use this cause-and-effect behavior to their advantage during mating season. During and after copulation, an act lasting an average of 17 minutes, the males emit a call that is indistinguishable from the aerial predator warning. Thus, any competing males are forced into hiding and leave the couple to finish their act uninterrupted. Since the females mate with 7-11 other males, this “alone time” can give the sperm a head start in fertilizing her eggs.

It’s a smart and delightfully deceptive trick.