In the wild, your mating call is often what sets you apart from the crowd.
In the case of frogs, males generally want to make sure that their calls reach the females loud and clear. For that reason, they tend to only vocalize their mating calls when no other frogs are doing so.
The pug-nosed tree frog, however, operates quite a bit differently. Rather than vocalizing one at a time, a group of pug-nosed tree frogs will all call at the same time.
Why Call Together?
Upon making this discovery, researchers were initially confused. It didn’t make a lot of sense. Ximena Bernal – a behavioral ecologist – suggested that perhaps the frogs called together to help confuse predators who might be listening to mating calls to ‘size up’ their prey.
While in the wild, frogs (and any other animal) need to be cautious. While their mating calls might alert the opposite sex that they’re interested in procreating, it also informs predators about where they are.
The pug-nosed tree frogs, it would seem, are well aware of this fact. They use their voices to help avoid and confuse prey.
When the tree frogs call out together, their voices band together to create an auditory illusion. This illusion tricks predators into thinking that the frogs are somewhere other than where they are.
Female pug-nosed tree frogs, on the other hand, are not duped by the illusion. This allows these frogs to simultaneously confuse their predators while attracting potential mates.
The Pug-Nosed Tree Frog’s Calling Card
When a frog calls out in the wild, there are – unfortunately for them – a number of other eavesdroppers. Predators like midges and bats are keen to learn the whereabouts of frogs so that they can get their next meal.
Most frogs prefer to send out a single call when nearby frogs are silent. This may announce their presence clearly to a mate, but also informs predators.
The pug-nosed tree frogs have developed a system that allows them to avoid this risk.
First, the ‘leading’ frog makes its call. Almost immediately afterwards, other males in the group make successive mating calls – one after another.
This is known as the precedence effect, and it confuses animals and humans into perceiving separate sounds as coming from the same source.
That said, this plan isn’t fool-proof. Any predators who listen to the synchronous mating call will be directed towards the leading frog – the one who makes the first call. So why would any frog want to take the risk of being the leader?
It turns out, the leading frog may not be designated. It seems that the rest of the frogs simply wait until one of their brethren can no longer suppress their mating call. Once it’s released, the rest of the frogs chime in, and the illusion proceeds from there.
It’s also interesting to note that female frogs aren’t receptive to the illusion. That means that they can determine the differences of the calls and can separate their potential mates from one another.
