Male birds up their defensive game when females are watching
Animal mobbing behavior is an interesting strategy used by the likes of small birds to team up and scare way would-be predators. Or so scientists have thought. In addition to this collaborative survival tactic, researchers have found that there may be another motivation for these cooperative swoops – a desire to impress onlooking females.
Mobbing behavior can be seen in various creatures across the animal kingdom including meerkats, squirrels and even fish. When it comes to small birds, tactics can include squawking, defecating on and swooping would-be predators to shoo them away from the area. It was though that this was simply a form of protection, but scientists from the University of Zurich together with a team from Brazil's Federal University of Ouro Preto suspected there may be an element of showmanship at play.
To explore this theory, the researchers conducted experiments where replicas of predatory owls were introduced to a bird community in Brazil. One was a model of a pygmy owl, which regularly eats birds, and the other was a model of a less-threatening burrowing owl.
The team watched on as 79 different bird species swooped at the models, keeping tabs on the mob size, the intensity of each individual and whether the behavior changed when females from the same species were watching on. It gathered data on only 19 species however, as these species were sexually dimorphic (meaning males and females could be easily distinguished from one another).
Mobbing increased in intensity when the less-threatening burrowing owl was introduced, something that aligns with previous research suggesting birds consider the risk from the predator when engaging in such activity. But more interesting were the fresh observations that mobbing intensity of the males was higher when females from the same species were watching.
"Females may use these mobbing events to assess a male's quality, for example their motor skills which allow them to escape from an attacking predator," says lead author of the study, Filipe Cunha of the University of Zurich. "This characteristic may provide clues about how well a male will be able to defend a nest or to forage."
The research was published in the journal Behavioral Ecology and Sociobiology.