A Bird’s Eye View

The beryl-spangled tanager belongs to one of the largest families of songbirds that reside primarily in Central and South America. This species, collected by the Moore Lab of Zoology, live in the northern Andes of South America. Credit: Joshua Medina/The Moore Lab

Bird’s don’t see the world just from above — they also can see a whole range of light that humans can’t. Humans have three types of cones in their eyes that process color. These photoreceptors are sensitive to red, green, and blue (much like a digital screen). Birds, on the other hand, have more precise color filters than humans so they can see a much deeper variation of colors; they also have a fourth cone cell that allows their vision to dip into the ultraviolet spectrum. Since humans can’t experience them, we currently don’t have names for these colors.

Shultz operates the reflectance spectrophotometer fiber optic probe on museum specimens. Credit: Allison Shultz/Natural History Museum of Los Angeles County

Assorted species of buntings in the genus Passerina showing both colorful males and brown females in the Moore Lab bird collection. Credit: John McCormack/The Moore Lab

This information has been well-known for about the last 20 years, but recently, scientists have been trying to see from the bird’s point of view. Allison Shultz, assistant curator of ornithology at the Natural History Museum of Los Angeles County, and John McCormack, director and curator of birds and mammals at the Moore Lab of Zoology at Occidental College in Los Angeles, are using techniques that require a reflectance spectrometer. It’s a device that uses a fiber optic probe that sends pulses of xenon light (light that encompasses the entire spectrum) on an object. The light that is reflected back tells researchers what colors are present on a bird’s plumage, including those only visible on the ultraviolet spectrum. However, this technique is not perfect; since it only examines one point at a time, it misses large patches of patterns.

Swatches of various scanned tanager species, which the Moore Lab uses for plumage color analysis. Left to right (click for high-resolution): beryl-spangled tanager, spotted tanager, golden-hooded tanager. Credit: Joshua Medina/The Moore Lab

Joshua Medina, a 3D artist and digitization specialist at the Moore Lab, uses a 3D technique called photogrammetry. Rotating a bird on a turntable, Medina takes hundreds of photos at different angles. He then composites the photos into a single flat image, which contains all the colors, textures, and patterning across the entire model. A researcher could then analyze every color on the specimen, which could be helpful in tracing the evolution of plumage colors and their purposes across species. All of the specimens are catalogued online and the Moore Lab is in the process of digitizing the entire collection in 3D. Next steps involve getting a UV camera set up to add another layer to the digital map. Through the work of Shultz, McCormack, and Medina, we are closer to getting an even more accurate picture of a bird through a bird’s eyes.

Visual effects artist Joshua Medina 3D images a tufted jay, Cyanocorax dickeyi. For a step-by-step guide of the 3D photogrammetry process, read Medina’s blog post on SketchFab. Credit: Joshua Medina/The Moore Lab

Various species of tanagers, a Central and South American songbird, preserved at the Moore Lab. Credit: John McCormack/The Moore Lab

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