This is Scientific Americans 60 Second Science.

I'm Jason Goldman.

As animals grow, the sounds they make change.

But some sounds continue to change even after an animal

matures. That's true for humans and now it turns out to be true for North Atlantic

right whales too.

A member of the Belene family of Wales, the endangered North Atlantic right whales spend most of

their time along the eastern coast of North America, from Canada's Bay of Fundy, south of Florida.

Syracuse University biologist Holly Root Gutridge analyzed recordings of whale calls to see if

researchers could use those sounds to identify individual whales.

In an audio program on a computer screen, a call has a particular shape.

Staring at these calls all day, I started to notice they were changing, and then we looked a little bit harder at the data and realized that they weren't just changing from being a little tiny baby to being and fair-sized adults, but they kept changing over time.

Root Gut Regener colleagues rounded up 17 years worth of whale recordings.

In all, they gathered nearly a thousand calls from 49 individual whales between the ages of one month and 37 years.

Like many other animals, the calls of the infants were both shorter and less structured

than those of the adults.

Mature whales produce calls that were clearer, longer, and more structurally complex.

But the researchers also found that the calls continued to develop long after the whales reached sexual and physical maturity.

Instead of just changing from the age of 0 to 15 when they're pretty much full grown, they kept changing after the age of 15 and just kept going throughout the whole lives.

Compared to say a bird, where usually they get to their full-grown state and then they don't change these calls.

The results were published in the journal Animal Behavior.

Well, it means that instead of just having a completely instinctive reaction

...