Tuning in to smallness

Posted by Yen Yi Loo @looyenyi 

How do you survive by being small? The soundscape in a New Zealand bush is filled with splendour. But among the powerful song and majestic plumage, there is a niche for all things small and sweet. In Boundary Stream Mainland Island, a forest reserve in the Hawkes Bay region, a group of tiny birds constantly flick and flutter in the trees; Tomtits, Grey warblers, Silvereyes, Robins…and the smallest of them all is the Rifleman. They are so small that a wing flap of a butterfly could be mistaken as a Rifleman. Not only that. They are also very difficult to hear. Rumour has it that people after about 50 years of age can’t hear them. And because of that, many don’t notice them among the Tūī, Bellbirds, and Kākā. I spent the first week of my PhD fieldwork tuning in to the high pitch calls of the Rifleman, tilting my head this way and that, like an owl, to pick up subtle wisps of conversation between foraging pairs. After some practice, I could finally tease apart the calls between Rifleman, Grey warblers and Tomtits, by their small differences in pitch and length.

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Spotting a rifleman takes a little patience and a good sense of auditory localization,
and also ways to watch from different perspectives!
© Ines Moran

I am a first year PhD student looking at the vocal learning abilities of the Rifleman. Could they be learners? Well, we know that they are not songbirds, because they don’t sing to defend their territory or to attract mates – or do they…? But findings in the past decade have also plucked them from the suboscine group and placed them as a link between the passerines and the parrots. So here we are, trying to decipher their potential hidden skill of vocal learning. The more I spend time with them, the more I learn about their interesting behaviours. For instance, they constantly open and close their wings while hopping on branches and trunks of trees in an incredible speed of about 0.05 seconds for each ‘flick’, maybe to maintain balance due to their short of tail? And I saw a male hover for one second in the air!

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“Whoa, didn’t see that branch there!”
© Yen Yi Loo

I can relate to the Rifleman in many ways. For one, I am small, even for Asian standards. For another, I speak softly – well, because I wouldn’t want to disturb the birds! And most relatable of all, I can’t sit still. Although the Rifleman don’t migrate or have large territories, they are busy little birds constantly communicating and working on staying alive. It is difficult to follow them because they move so quickly. I, too, am constantly moving; I travel the world from one side to the other, chasing little birds and learning their behaviour and language. Truth be told, there is a lot to learn wherever we go. And it led me here to this beautiful land of unique bird life. Being surrounded by the soundscape of this forest and the wonderful team that I’m working with, I am glad this is where I will spend all the summers of my PhD doing fieldwork!

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The Cain Lab on the first week at Boundary Stream Mainland Island.
From left, Me: cold and numb from the NZ spring rain,
Daria Erastova: looking to expand her incredible bird list,
Sarah Withers: the pioneer of Rifleman research in the North Island,
Ines Moran: my PhD team mate – the best I could ask for,
and Kristal Cain herself!

YenYen Yi Loo is a PhD student in the School of Biological Sciences, University of Auckland. Her study aims to determine whether the rifleman (Acanthisitta chloris) are vocal learners by investigating the ontogeny and temporal changes in their vocal parameters, and its implication on the evolutionary origins of vocal learning in the avian phylogenetic tree. She is supervised by Kristal Cain and Margaret Stanley.

 

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