Chapter 1: The Color Spectrum in Animal Behavior

The coloration of animals is significantly influenced by a universal sensory bias, which often results in darker hues being assigned to the more dynamic parts of their bodies, while brighter tones are used for the more static regions.

"The Bird's Concert" by Frans Snyders ~1630 — 1640. Image from WikiArt. Public domain.

This concept resonates with Dewitt H. Parker's observations from The Principles of Aesthetics (1920), where he suggests that colors evoke specific emotional responses. For instance, yellow is typically associated with happiness, blue with calmness, and red with passion, while orange blends the joy of yellow with the fervor of red. In essence, brighter and warmer colors tend to elicit feelings of joy and excitement, whereas darker, cooler colors foster a sense of restfulness.

Birds of Color: Case Studies

#### The Marvelous Spatuletail

The marvelous spatuletail (Loddigesia mirabilis), an endangered hummingbird from Peru, showcases a fascinating display during its courtship rituals. It alternates between exposing its vibrant purple crown and the green of its neck, depending on its movement. The bird's dance involves a mix of stillness and rapid side-to-side motion, where the color displayed correlates with its activity level—green during stillness and purple in motion.

This dynamic interplay of colors signifies a broader trend in avian coloration, where the more animated body parts, like wings and tails, tend to be darker, while less mobile areas, such as the breast and belly, are often brighter. This pattern suggests a universal preference for darker tones in dynamic contexts and lighter hues in stationary ones.

#### The Vogelkop Superb Bird-of-Paradise

Another excellent example is the Vogelkop superb bird-of-paradise (Lophorina niedda), where the black wings and tail engage in dramatic movements, contrasting with the bright blue invitation on its chest that remains stable throughout the performance. This stark dichotomy between dynamic darkness and bright stasis is essential for attracting mates.

#### The Western Parotia

The western parotia (Parotia sefilata) employs a similar strategy, where it dons a black "ballerina skirt" during its display. The male exhibits vibrant, shiny yellow plumage only after an intense, dynamic dance, creating a clear separation between motion and stillness.

The Role of Color in Mate Selection

The intriguing behaviors of the red-capped manakin (Ceratopipra mentalis) also highlight the theme of dynamic darkness and bright stasis. As it performs its moonwalk dance, the male keeps its bright red head still, contrasting with the darker parts of its body that vibrate, further emphasizing the color dynamics at play.

This configuration mirrors the Thayer effect, where most animals exhibit a brighter coloration on their undersides and darker on their tops, likely as a result of mate selection rather than solely for camouflage.

Dynamic Darkness in Other Species

Similar dynamics can be observed across various species. For example, the flame bowerbird (Sericulus ardens) uses the contrast of its vibrant head and darker wing feathers to attract females, reinforcing the idea that dynamic darkness plays a crucial role in animal displays.

General Patterns in Animal Coloration

Research shows that this dynamic darkness effect is prevalent across numerous bird species. For instance, a study revealed that approximately 62% of sampled birds exhibited darker wing tips compared to their breast colors. This pattern not only enhances their attractiveness but also suggests a universal preference for such color dynamics among animals.

The Psychology of Color and Motion

The relationship between color and psychological excitement is profound. Lighter colors, particularly those that lean towards red, are often associated with heightened emotional responses, while darker hues evoke a more subdued reaction. This psychological duality underscores the evolutionary significance of color in animal behavior and mate attraction.

Conclusion: The Evolutionary Implications

The prevalence of dynamic darkness and bright stasis in animal coloration points to a possible universal sensory bias that transcends species. This bias appears to be an innate trait rather than a learned one, as it manifests across a wide array of animals in various contexts, particularly during courtship displays.

The implications of these findings extend beyond mere aesthetics; they offer insights into the evolutionary pressures that shape animal behavior and mate selection, emphasizing the intricate relationship between color, motion, and attraction in the animal kingdom.

Works Cited

• McCoy, Dakota E., et al. "Structural absorption by barbule microstructures of super black bird of paradise feathers." Nature Communications 9.1 (2018): 1–8.
• Random Lists. "Random Bird Species — List of Random Birds." 2021. www.randomlists.com/birds.
• Parker, Dewitt Henry. The Principles of Aesthetics. United States, Silver, Burdett, 1920.