Nature’s Rhythms

Got the rhythm?

One way of thinking about rhythm is as sounds arranged in time. These sounds can exist outside of what might be considered music, say, in the form of beats, but music can’t exist without rhythm. The rhythm (or sounds) can be seconds or minutes long, or it can be a circadian (24-hour) or seasonal pattern. It may seem obvious, but nature’s bursting with both.

From birdsong to warning calls and whistles, species – and the biological communities they’re part of – rely on sounds for cues about behaviour, location, and survival.

Rock it, baby!

In Africa and the Middle East, there’s a rabbit sized, furry, Evolutionarily Distinct and Globally Endangered (EDGE) species called the rock hyrax. Like contestants in a talent show, male rock hyraxes who sing the most impressive songs while maintaining the rhythm, do well with the ladies. And they have better-surviving offspring than their less rhythmical peers to prove it!

The world’s only singing lemur performs its squeaks and honks in the stomp, stomp, clap rhythm of Queen’s, We Will Rock You. It’s a rhythm that only humans and birds were previously thought capable of producing. These talented indris use their rhythmic singing to mark out territory, find lost loved ones, and compete with neighbours. And if you’re after musical flourish, they can deliver, slowing songs down at the end ritardando-style.

Beluga whales use clicks, clangs, and whistles to communicate with buds in their pods while they hunt, migrate, and hang out together. Besides being decent mimics, these large, graceful mammals are also attracted by human songs, like those by Adele! (Fancy a boogie, Beluga?)

Musical flowers

And in case you were wondering, it’s not just animal species that have musical ears. Plants can hear, too! Evening primroses are so attuned to their soundscape that they increase the sugar in their nectar when bees approach. The hearing organ in question, their aptly shaped yellow petals, senses the insect’s wing vibrations before the pollinator arrives. This super-sweet nectar also makes more visitors likely, boosting the chances of healthy cross-pollination.

Noise, noise, NOISE

Why aren’t humans aware of all this sonic life? Well, for a start, not all species hear one another. Mammals, for instance, have lower pitch than birds or insects, meaning they can tune out irrelevant species and focus on their own – and their predators! Still, scientists can listen in to these natural ‘soundscapes’ to learn about different ecological environments and gauge how well they’re functioning.

Without doubt, they’re changing. As humans turn up the volume of mechanical sound, they drown out the delicate sighs, songs, and calls of nature. American soundscape ecologist Bernie Krause has been recording what he calls this ‘symphony’ of living organisms and natural habitats since the late 1960s. Over time, the work involved in recording has increased. In 2001, he noted that to get one hour’s pure natural sound (without human noise), what had taken 15 hours of recording now took 2,000. And that was more than two decades ago!

Killing the vibe

Jet planes flying over spadefoot toads as they vocalise simultaneously, can disrupt their vibe. Once the aircraft has passed and individual toads try to re-sync with the rhythm and the chorus, they draw unwanted attention to themselves … to the delight of predators.

Development and its faithful companion, habitat destruction, sadly means fewer species are around to make sounds. Changes in temperature, light, and day length related to climate change affect biological clocks. Some of the roughly half of birds that migrate, like EDGE whooping cranes, are starting their journeys earlier, and staying later.

In the ocean, altered migration patterns are changing underwater communities. Fewer blacktip sharks making their pilgrimage to Florida each spring, for example, have resulted in larger numbers of weaker species sticking around, threatening seagrasses and corals.