Ultraviolet reflectance by the skin of nestlings

Abstract

Birds can perceive the reflectance of ultraviolet light by biological structures. Here we show that the skin of the mouth and body of starling nestlings substantially reflects light in the ultraviolet range and that young in which this reflectance is reduced will gain less mass than controls, despite low background levels of ultraviolet and visible light in the nest. We suggest that this ultraviolet reflectance from starling nestlings and its contrast with surrounding surfaces are important for parental decisions about food allocation.

Yolk androgens do not appear to mediate sexual conflict over parental investment in the collared flycatcher Ficedula albicollis

“…2) If only males respond to the chick trait (hereafter a male-specific trait), males should increase their feeding rate with increasing yolk androgen levels while females should not change their investment. Previous studies have shown that it is possible that females and males respond to different components of nestling behaviour and phenotype, for example colour (Jourdie et al 2004, de Ayala et al 2007Ewen et al 2008;Galvan et al 2008;Tanner and Richner, 2008), size (reviewed in Slagsvold, 1997;Lessells, 2002), condition (e.g. Christe et al 1996) or visual vs. vocal cues of begging (Kilner, 2002, reviewed in Müller et al, 2007a.…”

Male Red-backed Fairywrens appear to enhance a plumage-based signal via adventitious molt

“…Juvenile birds can also convey condition via leg coloration, as in storks and raptors (Negro et al 2000, Casagrande et al 2009, Sternalski et al 2010, and the UV reflectance of nestling skin appears to be a signal that influences parental feeding (Jourdie et al 2004, Bize et al 2006. Juvenile American Coots (Fulica americana) display bright red skin on their head as well as orange feathers, which both appear to have evolved via parental favoritism for colorful chicks (Lyon et al 1994).…”

Ultraviolet reflectance by the cere of raptors

“…The emphasis so far has been on UV reflectance by plumage traits, but there is growing evidence that beaks, skin or soft sexual ornaments reflect in the near UV (e.g. Jourdie et al 2004;Dresp et al 2005). However, the functions of UV reflectance by fleshy ornaments and the mechanisms underlying quality signalling remain barely known.…”

“…Recent studies have suggested links between carotenoid based coloration and plumage (structural) UV reflectance, because carotenoid spectra often exhibit a secondary reflectance peak in the near-UV wavelengths (Burkhardt 1989;Bleiweiss 2004Bleiweiss , 2005. Many non-plumage features with UV reflectance are also carotenoid-based ornaments, like the gape of passerine nestlings ( Jourdie et al 2004), the combs of grouse (Mougeot et al 2005) or the yellow or orange beak of zebra finches (Bennett et al 1996), blackbirds (Bright & Waas 2002) and mallards (Peters et al 2004). Thus, UV and carotenoid based signals might not be independent.…”