Beyond colour: consistent variation in near infrared and solar reflectivity in sunbirds (Nectariniidae)

Date

2017

Authors

Shawkey, Matthew D.
Igic, Branislav
Rogalla, Svana
Goldenberg, Jonathan
Clusella-Trullas, Susana
D'Alba, Liliana

Journal Title

Journal ISSN

Volume Title

Publisher

Springer

Abstract

The visible spectrum represents a fraction of the sun’s radiation, a large portion of which is within the near infrared (NIR). However, wavelengths outside of the visible spectrum that are reflected by coloured tissues have rarely been considered, despite their potential significance to thermal effects. Here, we report the reflectivity from 300 to 2100 nm of differently coloured feathers. We measured reflectivity across the UV-Vis-NIR spectra of different (a) body parts, (b) colour-producing mechanisms and (c) sexes for 252 individuals of 68 sunbird (family: Nectariniidae) species. Breast plumage was the most reflective and cap plumage the least. Female plumage had greater reflectivity than males. Carotenoid-based colours had the greatest reflectivity, followed by non-iridescent and iridescent melanin-based colours. As ordered arrays of melanin-filled organelles (melanosomes) produce iridescent colours, this suggests that nanostructuring may affect reflectance across the spectrum. Our results indicate that differently coloured feathers consistently vary in their thermal, as well as obvious visual, properties.

Description

Keywords

Iridescence, Thermal, Infrared

Citation

Source

The Science of Nature (formerly Naturwissenschaften)

Type

Journal article

Book Title

Entity type

Access Statement

License Rights

Restricted until

2099-12-31