Related Experiment Video
Updated: Jun 7, 2025

Manipulation of Color Patterns in Jumping Spiders for Use in Behavioral Experiments
Published on: May 21, 2019
Uropygial secretion changes mouth colouration in starling nestlings
Antonio José García-Núñez1, Juan José Soler1,2, Ester Martínez-Renau1
1Departamento de Ecología Funcional y Evolutiva, Estación Experimental de Zonas Áridas (CSIC), Almería 04120, Spain.
Abstract:
Cosmetic colourations of animals have been mainly studied in scenarios of sexual selection, while there has been no assessment of the partial contribution of cosmetics to the final colouration of begging-related traits. In birds, the uropygial gland is functional soon after hatching, and we experimentally investigated the effects of uropygial secretion on mouth-flange colouration in spotless starling (Sturnus unicolor) nestlings. Nestlings' flange colouration was measured with a spectrophotometer before and after being either cleaned of, or painted with, its own uropygial secretion. After cleaning, flanges were brighter, more UV and less yellow-red coloured (chroma). Instead, painting the mouth flanges of nestlings with their own uropygial secretion did not modify any of the considered colour components. Our findings therefore show that the uropygial secretion of nestlings alters their beak colouration and open the possibility for future research to investigate the role of uropygial secretion in reinforcing the signalling role of begging-related traits involved in parent-offspring communication.
Related Concept Videos
Mate Choice
Pigmentation
Melanin occurs in two primary forms: eumelanin that provides black and brown pigment and pheomelanin that provides red color. Dark-skinned individuals produce more melanin than those with pale...
Predator-Prey Interactions
Fixed Action Patterns
Speciation Rates
What is Natural Selection?

