Dave’s planet: Decoding birdsong this summer

Dave Pepler decodes the accompaniment to our daily life in the tree-lined streets and gardens of Stellenbosch: birdsong.

The Cape white-eye is one of the renowned members of the dawn chorus. Its song is composed of a series of long warbling phrases that vary in pitch, tempo and volume. These voluble little birds produce a sweet melody that makes you grateful for the new day.

When Dame Ethel Smyth turned 72, she fell in love with Virginia Woolf. Poor Virginia was completely overwhelmed by this larger-than-life woman and described the unrequited affection as “like being caught by a giant crab”. But to give Ethel her due, she had a marvellous capacity for enjoying life while composing rather dreary music on the hoof. She lost her hearing as she got older but, while visiting Virginia and Leonard, at the end of the day she would take her huge ear trumpet, lie down on the lawn and listen to the evensong of nightingales. For this exuberant joie de vivre I shall always admire Ethel.

One can be certain that she listened to the haunting song of the nightingales as a creator and lover of music, but birds sing for many, many more reasons than to entertain English composers. Some of the songs of birds can be melodic, pure of tone and sweet on the ear, but other calls can be harsh and grating, like drawing your nails over an old-fashioned blackboard. Think barn owl here…

Rarely do birds sing for their pleasure, simply because singing is a high-risk and energy-hungry activity. High-risk? For sure, if singing gives your position away to a hungry predator. For this reason, the first songsters of the day, usually olive thrushes and Cape robin-chats, are known to have the best eyesight in low-light conditions. And the dawn message? “This is my branch, my tree, my territory!” Of course, the ladies will also be listening, judging the singer’s fitness by the volume and complexity of his song.

So why do birds sing? Given that most birds live in groups or flocks, the very first message conveyed, through a song or call, is about the whereabouts of food sources. In Stellenbosch, red-winged starlings are superb exponents of this ‘food melody’ and may be seen in old estates with fruit trees, such as the lovely Johnman Garden, where their flute-like notes drift down from tall hedges. Birds also sing to attract mates, and their compositions, which is what they actually are, can either be a unique sequence of notes and imitations of other species or a duet, gracefully repeated by the pair as if choreographed. Most owl species and many of the shrikes communicate love songs in this way.

Another reason for singing is, as mentioned, to claim territory. In its extreme form, such singing is performed by brood parasites such as the familiar piet-my-vrou, or red-chested cuckoo, whose endlessly repeated call on a calm spring morning can drive one to distraction. Another function of calls is to keep members of a feeding or breeding flock in contact with one another with the message “I’m still here, where are you?”. The last call type is one warning that a predator is approaching. Much like meerkats guarding their families, birds such as starlings and woodpeckers are supreme early-warning systems for the foraging group.

When birds add changes in posture to their warbling – in the same way human singers can express emotion by simple hand movements – an even more complex message can be conveyed. This coding can be subtle, much like Cecilia Bartoli’s slight hand curling, or completely over the top, as when Callas gave her infamous farewell tour, her slender hands like restless serpents.

Stellenbosch is one of the loveliest towns in South Africa. We have glorious mountains cupping the village, a leafy river, grand open spaces and, most importantly, some of the finest trees to be found on any street. This natural architecture is home to a breathtaking assemblage of birds, from delicate white-eyes to raucous crows and hadedas. By taking time to learn the calls of our town’s birds, you can become entwined in this truly fascinating avian dialogue.

Dave Pepler is a landscape ecologist and naturalist interested in the living world and how we interact with the environment.

Read more…