It’s no secret that humans sometimes lie to get each other into bed. However, in other species, evidence for tactical deception between the sexes has been hard to come by. A new study in The American Naturalist shows that the males of an African antelope species will emit false predator alarm calls in order to keep females on their territories for extra mating opportunities.

The four-year study looked at the behavior of topi antelopes (Damaliscus lunatus) in the Masai Mara National Reserve in Kenya. This area is dominated by a huge number of predators, including lions, cheetahs, leopards, and hyenas, all of which prey regularly on antelopes. When topi detect a predator nearby, they often make snort-like alarm calls.

From February to March, male topi hold small territories through which receptive females pass to assess each male’s mating potential. The authors noticed that, while a female in estrus was on a male’s territory, the male would sometimes emit alarm calls, even in the complete absence of a predator. These false alarms are acoustically indistinguishable from true alarm snorts.

The authors set out to determine whether these false alarm snorts are simply predator detection errors, or if they function to deter the female from leaving the territory in order to secure more mating opportunities with her. The results overwhelmingly supported the authors' "sexual deception hypothesis." False alarms almost never occurred without a receptive female on the territory, the onset of the false snorts was highly correlated with a female’s attempts to leave the territory, and, after emitting a false snort, males managed an average of 2.8 extra booty calls.

So why do females keep responding to the deceptive males' tricks? For one, they’re only subjected to false calls once a year during their one-day estrus period. Perhaps more importantly, while the cost of falling for a false alarm is relatively low, the cost of ignoring a true alarm snort and wandering into the jaws of danger is high enough that it just doesn’t make sense for the females to risk it.

The American Naturalist, 2010. DOI: 10.1086/653078 (About DOIs).