ArticleDie Naturwissenschaften2008
Carotenoid-based bill and eye ring coloration as honest signals of condition: an experimental test in the red-legged partridge (Alectoris rufa).
Article in Die Naturwissenschaften, 2008. The graph could read no effect estimate from its abstract, so it casts no vote on the map. Cited by 20 papers, 1 of them a synthesis that pooled it.
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The abstract states no effect estimate the extractor could read, or names no intervention and outcome on the map, so this paper lights no cell and moves no belief. It is still indexed, cited and linked below.
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Who cites it
20 citing papers in PubMed, 1 synthesis or guideline pooled it, 82 citations in OpenAlex.
- Pooled it
- Seasonal dynamics of female bill colouration: an observation in captive House Sparrows (Journal of ornithology · 2026Article
- The Impairment of Body Condition Transiently Increases Oxidative Stress: A Dietary Restriction Experiment in Partridges.Journal of experimental zoology. Part A, Ecological and integrative physiology · 2025Article
- Facial blushing and feather fluffing are indicators of emotions in domestic fowl (Gallus gallus domesticus).PloS one · 2024Article
- Article
- The dark ventral patch: A bimodal flexible trait related to male competition in red deer.PloS one · 2020Article
- Carotenoid-based coloration predicts both longevity and lifetime fecundity in male birds, but testosterone disrupts signal reliability.PloS one · 2019Article
- The fractal dimension of a conspicuous ornament varies with mating status and shows assortative mating in wild red-legged partridges (Alectoris rufa).Die Naturwissenschaften · 2018Article
- Article
- Coloured ornamental traits could be effective and non-invasive indicators of pollution exposure for wildlife.Conservation physiology · 2016Review
- Astaxanthin and papilioerythrinone in the skin of birds: a chromatic convergence of two metabolic routes with different precursors?Die Naturwissenschaften · 2014Article
- The interplay between gonadal steroids and immune defence in affecting a carotenoid-dependent trait.Behavioral ecology and sociobiology · 2011Article
- Integument coloration signals reproductive success, heterozygosity, and antioxidant levels in chick-rearing black-legged kittiwakes.Die Naturwissenschaften · 2011Article
- Free radical exposure creates paler carotenoid-based ornaments: a possible interaction in the expression of black and red traits.PloS one · 2011Article
- Multiple coloured ornaments in male common kestrels: different mechanisms to convey quality.Die Naturwissenschaften · 2011Article
- Differential effects of testosterone, dihydrotestosterone and estradiol on carotenoid deposition in an avian sexually selected signal.Journal of comparative physiology. A, Neuroethology, sensory, neural, and behavioral physiology · 2011Article
- Carotenoid-based bill colour is an integrative signal of multiple parasite infection in blackbird.Die Naturwissenschaften · 2010Article
- Carotenoid maintenance handicap and the physiology of carotenoid-based signalisation of health.Die Naturwissenschaften · 2010Review
- Testosterone-mediated trade-offs in the old age: a new approach to the immunocompetence handicap and carotenoid-based sexual signalling.Proceedings. Biological sciences · 2009Article
- Resource-dependent investment in male sexual traits in a viviparous fish.Behavioral ecology : official journal of the International Society for Behavioral EcologyArticle
Corrections and comments
PubMed lists nothing against this paper. Absence here is not a guarantee, only a check that was made.
Authors and funding
2 authors at 1 institution in 2 countries.
Funding
No grant is acknowledged in the PubMed record.
Abstract
Carotenoid pigments cannot be synthesized by vertebrates but must be ingested through the diet. As they seem to be a limited resource, carotenoid-based ornaments are particularly interesting as possible honest signals of individual quality, in particular of foraging efficiency and nutritional status. Some studies have demonstrated the condition dependence of carotenoid-based plumage in birds. However, many other carotenoid-pigmented bare parts (i.e. skin, caruncles, bills, cere, and tarsi) are present in birds but, in comparison with plumage, little is known about these traits as indicators of individual quality. Here, we show that the eye ring pigmentation and bill redness of the red-legged partridge (Alectoris rufa) are positively associated to body condition and recent changes in body mass. Also, we found a negative relationship between these two traits and heterophil-to-lymphocyte ratio, an indicator of physiological stress (the relationship with bill redness being significant only for males). In an experiment, we found that after a period of reduction in food intake (with the consequent loss of body mass), food-restricted birds showed lower eye ring pigmentation than ad-libitum-fed birds. Therefore, different ornaments seem to reflect changes in body condition but at different speeds or intensities (eye ring, a fleshy ornament, appears to respond more rapidly to changes in the nutritional status than a keratinized structure as the bill). These results indicate that carotenoid-based ornaments are condition-dependent traits in the red-legged partridge, being therefore susceptible to be employed as honest signals of quality in sexual selection.
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