Meeting Abstract
The relationship between animal signals and signaling environment is an active area of research, especially with regard to the adaptation of animal color with respect to visual environment. Recent studies in visual communication have integrated behavior, exploring the interaction between static color signals and dynamic visual displays. However, only recently have all three components – color, display and environment – began to be analyzed together. Old World leaf warblers in the genus Phylloscopus are a classic example of the Sensory Drive Hypothesis. In the Western Himalaya, previous research has shown a correlation between habitat darkness and degree of ornamentation, such that species occupying darker habitats have a greater quantity of plumage patches (Marchetti 1993). However, motion in the form of display behaviors also plays a key role in how a visual signal is presented and perceived. With the accessibility of affordable high-speed video cameras, these rapid behaviors can now be quantified and analyzed. We filmed territorial display behaviors of 7 species of Phylloscopus warbler and one Horonis warbler in the Western Himalaya. We then analyzed the display behaviors by tracking trajectories of wing motion and quantifying shape changes and wing flick rate. Significant variation was found in both the trajectory of wing display behaviors as well as wing flick rate. This work broadly confirms that species with signaling patches tend to display their wings, and this behavior varies interspecifically. A notable exception is in one species that has no patches but lives in exceptionally dark habitats. We discovered this species has a hidden, achromatic patch that is only visible during display, likely functioning in short-range communication.
