Animal Form and Function

// biomechanics // performance // communication behaviors

When you work in a natural history museum long enough - perhaps after one or two days - you start seeing the objects it contains as much more than simple artifacts or curiosities. Suddenly, everywhere you look there are fragments of complex, multifaceted stories about animals, their habits and habitats, and the scientists that studied them. A matchbox containing a single one-centimeter-long bone transforms from an esoteric oddity to a centuries-long saga about Russo-American international relations, a scheme involving five nuclear bombs, and a question about basic animal anatomy that - to this day - remains a mystery.

 

Well, at least that's how it happened for me. 

That tiny matchbox led me to discover, deep in the bowels of the Slater Museum of Natural History, a series of over-stuffed, grease-stained boxes of every size and shape all containing a single type of unusual bone: the baculum. Yes, that's right, I had just discovered the museum's collection of penis bones. Thousands of individual specimens representing everything from weasels to walruses, gophers to grizzlies - I was utterly baffled by their diversity and frankly astonished by the fact that I hadn't even known these structures existed in mammal bodies (textbooks often skip over the fascinating field of phallology). Little did I know that this moment of discovery would be the start of my journey to becoming a professional functional anatomist and an impassioned advocate for natural history artifacts as tools to 

 

/researcher

Feather shapes P7 inverted.png

Above: a spectrogram of Mourning Dove wing sounds.    The first written accounts of the Mourning Dove always included a description of their odd wing sounds. From John James Audubon to Alexander Wilson, the "whistling wings" of these elegant birds have intrigued ornithologists for centuries. Could feather mophology be specialized for sound-production, instead of force-produciton? Listen to the sound below. (Audio by Andrew Spencer 2009)

XC35100 - Mourning Dove - Zenaida macrouraAndrew Spencer - xeno-canto.org
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Columbina ground dove feather barbs

Specialized Shapes for Sonations

 

Some unique remex morphologies are specialized for producing sounds in flight. These locomotion-induced acoustic signals, known as sonations, likely communicate alarm or are involved in sexually selected displays. But what sorts of morphologies can produce sounds? And how do we distinguish between those sounds that are spurious and those that are communicative?

 

Right: unusual feather shapes in Columbina doves produce buzzing sonations in flight.  

Pink-necked Green Pigeon (Treron verans) wing feathers

Remex Diversity in Columbidae

 

Notches, elongated barbs, narrow feathers, emarginations - these odd feather shapes can be found in more than a third of all pigeons and doves, but why do they exist? Could they influence sound production? Or are they specialized aerodynamic devices? How do they evolve, and why don't they conform to the stereotyped shapes found in all other flying birds?

 

Left: green pigeons (Treron spp.) have remiges that have intrigued naturalists for two centuries.

Superb Fruit Dove (Ptilinopus superbus) wing feathers

Specialized Aerodynamic Devices

 

Some feather morphologies are thought to produce extra lift during take-off, or increase efficiency while soaring. Could these strange feather shapes in pigeons and doves be similar aerodynamic devices? If so, under what circumstances do such morphologies evolve, and why aren't they present in more species?

 

Left: this odd P10 feather increases flight efficiency and can be found in a quarter of all columbids.